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What increases calcium absorption: Vitamin D and Intestinal Calcium Absorption

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Vitamin D and Intestinal Calcium Absorption

Mol Cell Endocrinol. Author manuscript; available in PMC 2012 Dec 5.

Published in final edited form as:

PMCID: PMC3405161

NIHMSID: NIHMS306628

Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School and Graduate School of Biomedical Sciences, Newark, New Jersey 07103

To Whom Correspondence Should be Addressed: Sylvia Christakos, Ph.D., UMDNJ-New Jersey Medical School, Dept. of Biochemistry and Molecular Biology, 185 South Orange Ave., Newark, New Jersey 07103, 973 972 4033 (phone) 973 972 5594 (FAX), [email protected] other articles in PMC that cite the published article.

Abstract

The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D3 (1,25(OH)2D3) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)2D3 can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.

Introduction

Studies in vitamin D receptor (VDR) null mice have indicated that the principal function of vitamin D in mineral homeostasis is to increase calcium absorption from the intestine (Li et al., 1997, Yoshizawa et al., 1997). This conclusion was made based on the findings that rickets and osteomalacia are prevented and serum calcium and parathyroid hormone (PTH) are normalized when VDR null mice are fed a rescue diet high in calcium and lactose. In the event of decreased calcium levels in the serum due to low dietary intake or increased demand of calcium due to growth, pregnancy or lactation, the synthesis of the hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is increased leading to increased intestinal calcium absorption. If normal serum calcium is unable to be maintained by intestinal absorption, then 1,25(OH)2D3 together with PTH will mobilize bone calcium and increase reabsorption of calcium from the renal distal tubule.

1,25(OH)

2D3 and Transcellular Calcium Absorption

In the intestine 1,25(OH)2D3 affects the process of transcellular calcium transport which has been proposed to involve entry of calcium via the apical calcium channel, transient receptor potential vanilloid type 6 (TRPV6), translocation of calcium through the interior of the enterocyte (it has been suggested that the calcium binding protein calbindin-D9k acts to facilitate calcium diffusion through the cell) and basolateral extrusion of calcium by the intestinal plasma membrane pump PMCA1b (Wasserman 2005) (). Previous studies provided indirect evidence for a role of TRPV6 and calbindin in intestinal calcium absorption. Both are co-localized in the intestine, they are both similarly regulated [induced at weaning (the time of onset of active intestinal calcium transport), under conditions of low dietary calcium and after 1,25(OH)2D3 injection] (Song et al., 2003). TRPV6 and calbindin-D9k are both induced prior to the peak of intestinal calcium absorption (Song et al., 2003). In addition, in vitamin D receptor (VDR) KO mice, where the major defect that results in rickets is the decrease in intestinal calcium absorption, there is a 50% reduction in intestinal calbindin-D9k mRNA and a more marked decrease in TRPV6 mRNA (less than 5 – 10% of the levels in wild type (WT) mice) (Li et al., 1998, Van Cromphant et al., 2001). However, recent studies using calbindin-D9k knock out (KO) mice and TRPV6 KO mice have challenged the traditional model of vitamin D mediated transcellular calcium absorption in the intestine (Kutuzova et al., 2006, Akhter et al., 2007, Benn et al., 2008, Kutuzova et al., 2008, Bianco et al., 2008). Calbindin-D9k KO mice show no difference in phenotype compared to WT mice and they maintain normal serum calcium (Kutuzova et al., 2006, Akhter et al., 2007, Benn et al., 2008). Active intestinal calcium transport is similarly induced in both calbindin-D9k KO mice and WT mice in response to a low calcium diet or 1,25(OH)2D3, suggesting that calbindin-D9k may be compensated by another calcium binding protein (Benn et al., 2008). Calbindin may have another role in the intestine. Calbindin-D9k may be a modulator of the activity of TRPV6 and/or calbindin may act as a cytosolic buffer to prevent toxic levels of calcium from accumulating in the intestinal cell when there is an increase in apical calcium entry. TRPV6 KO mice also maintain normal serum calcium levels (Benn et al., 2008, Kutuzova et al., 2008). In response to 1,25(OH)2D3 intestinal calcium transport is similar in WT and TRPV6 KO mice (Benn et al., 2008, Kutuzova et al., 2008). However, under conditions of low dietary calcium, compared to WT mice, intestinal calcium transport is less efficient in the TRPV6 null mice (Benn et al., 2008). Also, in response to restriction of dietary calcium, although impaired bone mass accrual is comparable in WT and TRPV6 null mice, there is an increase in osteoblast activity and osteoid abundance is more pronounced in the TRPV6 null mice, suggesting a role for TRPV6 under low calcium conditions in intestinal calcium absorption to maintain proper bone mineralization (Lieben et al., 2010). When dietary supply of calcium is normal, lack of TRPV6 did not affect bone mass, remodeling parameters or growth plate morphology in young adult or aging mice. Thus, under normal calcium intake, TRPV6 is redundant for intestinal calcium transport, suggesting compensation by another channel or protein. Although the phenotype is mild, studies in the TRPV6 null mutant mice suggest that TRPV6 does contribute to the calcium absorptive process during calcium restriction. Recent studies showed that TRPV6 can interact with other proteins including calmodulin, which facilitates rapid inactivation of TRPV6, S100A10-annexin 2 protein complex which maybe involved in constitutive trafficking of TPRV6 to the plasma membrane and Rab11a which plays a role in recycling of TPRV6 to the plasma membrane (Derler et al., 2006, Van de Graaf et 2003, Van de Graaf et al, 2006). These TRPV6 associated proteins may represent novel components of the regulation by 1,25(OH)2D3 of calcium entry into the intestinal cell. Recent preliminary results show that transgenic mice overexpressing TRPV6 throughout the intestine (from duodenum to distal colon) of WT mice develop hypercalcemia, hypercalciuria and soft tissue calcification (Cui and Fleet, 2010). Although TRPV6 is not critical for 1,25(OH)2D3 mediated intestinal calcium absorption and maybe compensated by another channel yet to be identified, these studies indicate that TRPV6 does have a role in the process of intestinal calcium absorption.

Models of vitamin D mediated intestinal calcium absorption. Left panel: Transcellular intestinal calcium absorption. 1,25(OH)2D3, through its genomic actions, stimulates active intestinal calcium absorption. The traditional model of transcellular calcium transport involves calcium influx through TRPV6, intracellular calcium transfer by calbindin (CaBP) and calcium extrusion by the plasma membrane calcium ATPase (Ca pump). Recent studies using KO mice have suggested that TRPV6 and calbindin are not critical for 1,25(OH)2D3 calcium absorption and maybe compensated by another channel or protein. Right panel: Paracellular pathway. There is increasing evidence that 1,25(OH)2D3 can enhance paracellular calcium diffusion by regulating tight junction proteins. (Reproduced with permission from Wasserman RH, 2005).

Paracellular Calcium Transport

Calcium transverses the intestine by both the active transcellular pathway and the passive paracellular pathway (Hoenderop et al., 2005) (). The paracellular pathway functions throughout the entire length of the intestine and predominates in the more distal regions. This pathway is driven by the luminal electrochemical gradient and the integrity of the intercellular tight junctions (Tuskita et al., 2001). Recent evidence suggests that transjunctional transport of calcium by the paracellular pathway occurs in a regulated fashion, and may be coupled to active transcellular movement of calcium in a coordinated manner (Fujita et al., 2008). Tight junctions are specialized membrane domains located between the apical and basolateral membranes of the enterocyte, which form a barrier to the movement of ions, proteins, and other macromolecules across the intestine by maintaining a charge and size selectivity (Tuskita et al., 2001). Claudins are the major transmembrane components of tight junctions (Tuskita et al., 2001, Furuse et al., 1998) and it has been suggested that 1,25(OH)2D3 can promote paracellular calcium diffusion by increasing junction ion permeability (Fujita et al., 2008, Kutuzova and DeLuca 2004). VDR knockout mice, known to exhibit reduced intestinal calcium absorption, have decreased levels of claudin-2 and claudin-12 mRNA and protein (Fujita et al., 2008). In addition, 1,25(OH)2D3 has been shown to induce the expression of claudin-2 and claudin-12 in vitro in an intestinal epithelial cell line resulting in facilitated paracellular calcium conductance (Fujita et al., 2008). Gene array studies have shown that in addition to the known target genes, TRPV6 and calbindin-D9K, 1,25(OH)2D3 suppresses a number of intra- and intercellular matrix proteins including cadherin-17 (a cell adhesion protein) and aquaporin-8 (a tight junction channel), suggesting that vitamin D regulates intestinal calcium absorption via the paracellular pathway in addition to the transcellular pathway (Kutuzova and DeLuca 2004). It is possible that these other factors may compensate for the lack of TRPV6 in the TRPV6 KO mouse and thus may explain, in part, the mild phenotype of the TPRV6 KO mouse and the TRPV6/calbindin-D9k double KO mouse. Future studies examining different regions of the intestine and the identification of novel 1,25(OH)2D3 regulated proteins involved in transcellular and paracellular calcium absorption are needed.

Pregnancy, Lactation, Estrogen and Prolactin and Intestinal Calcium Absorption

Although 1,25(OH)2D3 is the principal hormone regulating active intestinal calcium absorption, other hormones have been shown to influence the process as well. Increased intestinal calcium transport has been observed in vitamin D deficient pregnant and lactating rats (Halloron and Deluca 1980, Boass et al., 1981, Brommage et al 1990). In addition, estradiol replacement in ovariectomized rats has been reported to result in an increase in intestinal calcium absorption without a stimulation of circulating 1,25(OH)2D3 levels (O’Loughlin and Morris, 1998). Studies by Van Cromphaut et al (Van Cromphant et al., 2003) in VDR KO mice showed that estrogen treatment after ovariectomy as well as pregnancy and lactation result in an induction of TRPV6 in the duodenum. In addition, in estrogen receptor α (ERα) KO mice, TRPV6 is reduced (Van Cromphant et al., 2003). These findings suggest that estrogens, independent of vitamin D, may be important regulators of calcium influx into the enterocyte and that these effects are mediated by ERα. In addition to estrogen, prolactin, a lacotgenic polypeptide hormone that is elevated during pregnancy and lactation, has been shown to have calcium regulatory effects. Prolactin has been reported to stimulate active intestinal calcium transport in vitamin D deficient rats (Pahuja and Deluca 1981). In addition, a direct effect of prolactin on active duodenal calcium transport was shown in studies using the Ussing chamber technique and prolactin applied to the incubation solution (Charoenphandhu et al., 2001). Studies in our laboratory indicate that prolactin can regulate TRPV6 in the duodenum independent of vitamin D, and also has cooperative effects with 1,25(OH)2D3 in regulation of both the intestinal calcium transport proteins TRPV6 and calbindin-D9K (Ajibade et al., 2010). Because both 1,25(OH)2D3 and prolactin levels are elevated during lactation (Halloron and Deluca 1980, Halloron et al. 1979, Pike et al., 1979, Meites et al 1972), prolactin may act together with 1,25(OH)2D3 to increase active intestinal calcium absorption. In addition, we found that prolactin has a direct effect on the transcription of the 1α(OH)ase gene, thus enhancing 1α(OH)ase protein expression and increasing levels of 1,25(OH)2D3 during lactation when there is an increased calcium requirement for the neonate (Ajibade et al., 2010). It has been suggested that prolactin also has an effect on the paracellular pathway of intestinal calcium absorption through upregulation of claudin-15 (Charoenphandhu et al., 2009).

Glucocortiocoids and Intestinal Calcium Absorption

Because of their potent anti-inflammatory and immunosuppressive properties, glucocorticoids are effectively used to treat inflammatory conditions such as asthma and rheumatoid arthritis. However, long term treatment with glucocorticoids reduces bone mineral density leading to osteoporosis (Reid 1997). In addition to direct effects on bone, glucocorticoids can also induce bone loss through diminished intestinal calcium absorption (Reid 1997, Huybers et al., 2007). In mice it has been reported that treatment with pharmacological doses of glucocorticoids results in decreased intestinal calcium absorption which is associated with a decrease in TRPV6 and calbindin-D9K (Huybers et al., 2007, Lee et al., 2006). Studies in cortisol treated chicks also noted an inhibition of intestinal calcium absorption which was associated with a decrease in calbindin (Feher and Wasserman, 1979). It has been suggested that the effect of glucocorticoids on calcium transport proteins can be independent of vitamin D (Huybers et al., 2007, Feher and Wasserman, 1979).

Effect of Aging

In aging, intestinal calcium absorption declines resulting in increased PTH which correlates to an age-related increase in bone turnover (Bullamore et al., 1970, Ledger et al., 1995). It has been proposed that the defect in intestinal calcium absorption is related both to low circulating levels of 1,25(OH)2D3 and to intestinal resistance to the action of 1,25(OH)2D3 (Wood et al., 1998). Either no change or a small decrease in intestinal VDR number has been reported with aging (Wood et al., 1998, Halloran and Portale, 2005). The expression of TRPV6 and calbindin-D9k declines with age and this decline is correlated to the decrease in intestinal calcium absorption and serum 1,25(OH)2D3 (Brown et al., 2005). In mice deficient in klotho (a multifunctional protein involved in phosphate and calcium homeostasis) a premature aging phenotype has been described (including short lifespan, infertility, atherosclerosis, skin atrophy and osteoporosis) (Kuro-o et al., 1997). Klotho functions as an essential cofactor for FGF23 which has been shown to regulate phosphate homeostasis and vitamin D biosynthesis (Kurosu et al). FGF23 and klotho, the FGF cofactor, suppress the expression of 1α(OH)ase and induce 24(OH)ase in kidney (Tsujikawa et al., 2003). Compared to WT mice, klotho KO mice have increased serum calcium and phosphate and decreased serum PTH (Kuro-o et al., 1997). Klotho KO mice also display increased serum levels of 1,25(OH)2D3 and increased expression of 1α(OH)ase (Tsujikawa et al., 2003, Yoshida et al., 2002). In the intestine klotho KO mice show increased expression of TRPV6 and calbindin-D9k and increased intestinal calcium absorption (Alexander et al., 2009) (in contrast to the decline observed in aging mice and rats; Brown et al., 2005). Thus the “aging” phenotype of the klotho KO mouse may reflect, at least in part, the effect of overproduction of 1,25(OH)2D3 rather than an effect on intestinal calcium absorption which contributes to bone loss in aging.

Calcium absorption, vitamin D and the distal intestine

In the calcium absorptive process the duodenum has been the major focus of research due to its highly active transport system. However, it is the distal intestine where 70- 80 % of the ingested calcium is absorbed (mostly in the ileum) (Wasserman 2005). Thus, it is important to understand the process by which the distal segment transports calcium. The vitamin D dependence of calcium absorption in the ileum and the colon has been shown (Petith et al., 1979, Lee et al., 1981, Favus et al., 1980, Favus, 1985, Vergne-Marini et al., 1976). VDR is expressed in all segments of the small and large intestine (highest levels have been reported in the cecum and colon) and in patients with extensive resection of the small intestine, calcium absorption has been reported to be significantly higher when the colon is preserved (Hirst and Feldman 1981, Stumpf et al., 1979, Xue and Fleet 2009, Hylander et al., 1990). 1,25(OH)2D3 has been shown to convert regions of net secretion of calcium in ileum and colon to net absorption (Favus 1985). The cecum has also been reported to be involved in 1,25(OH)2D3 mediated active transport (Favus and Angeid-Backman 1985). TRPV6 protein and calbindin-D9k protein are present in all segments of the mouse and rat intestine (immunocytochemical studies have indicated that the strongest expression of TRPV6 is in the cecum and colon) (Teerapornpuntakit et al., 2009, Zhang et al., 2010). Together these findings indicate that the distal segments of the intestine, in addition to the duodenum, play an important role in 1,25(OH)2D3 mediated calcium homeostasis. Our studies in the TRPV6/calbindin-D9k double KO mice indicate that we are missing important information related to the mechanisms involved in the regulation of intestinal calcium transport by 1,25(OH)2D3. Identification of multiple mechanisms by which 1,25(OH)2D3 acts to increase calcium absorption in different segments of the intestine is needed in order to identify new approaches to sustain calcium balance.

Acknowledgments

This work was supported by National Institutes of Health Grant DK38961-22 to SC

Footnotes

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Calcium Supplements & Absorption | MUSC Health

Osteoporosis is a very common problem that leads to broken bones and poor posture in aging women and men.

To prevent the loss of bone mass, it is important to have sufficient calcium in the blood that is transported to the bones. Although calcium is abundant in dairy products like milk, the amount of calcium that we need increases as we age. Since many people quit eating or drinking food products with calcium, such as whole milk, due to a health-related diet, a dietary supplement with calcium is important. Older adults require approximately 1,200 milligrams of calcium per day. 

The remainder of this article addresses ways to get enough calcium to keep bones strong. The healthiest sources of calcium are from foods that are rich in calcium, including most dairy products, cheeses, fortified orange juice and leafy green vegetables, which can provide at least 100 milligrams of calcium. A balanced diet provides most calcium needed by older adults. However, additional calcium must be ingested to reach a required 1,200 milligrams per day. The body can handle more than the minimum requirement of calcium. However, the body cannot manufacture calcium if too little is ingested.

Calcium Supplementation

All calcium ingested is not absorbed into the body. The small intestine, which is the part of the digestive system just beyond the stomach, is where calcium is taken by the blood and transported to bone and other tissues. The amount of calcium absorbed is dependent on several key factors:

  • Amount of calcium already in the blood
  • Form of calcium (diet or formulation)
  • Small intestine conditions

Calcium typically comes as a liquid or tablet carbonate or citric acid preparation. The carbonate requires acid in the intestine that generally is generated with food in the stomach. Therefore, carbonate pills should be taken with meals by people taking calcium to increase calcium absorption. Calcium citrate is soluble and does not require meals for absorption. Most commonly used calcium supplements come as a carbonate form and should be taken during or immediately after meals. Check the label of your calcium supplement to determine which form you have and when to take it. 

Approximately 500 milligrams of calcium can be taken at one time. Therefore, do not take all supplements at the same time. If you and your doctor have agreed you need supplementation, be sure to take it three times a day or approximately one-third at a time. To avoid taking too much, do not take more than 2,500 milligrams per day.

Vitamin D also is required for calcium absorption. The best source of vitamin D is sunshine for approximately 20 minutes per day, which is not a problem for most people who live in the South. Vitamin D also is found in many other sources and generally is not responsible for poor calcium absorption. On the other hand, estrogen facilitates calcium absorption. After menopause, some women lose their ability to easily take up calcium. For this reason, calcium generally is given at menopause as a vitamin supplement.

The Bottom Line

As we age, we need calcium to prevent weak bones and fractures. Both women and men should take an additional 1,000 to 1,500 milligrams a day after first consulting a physician. Three doses of 500 milligrams of calcium should be taken each day, preferably with a meal, for healthier bones and other tissues.

Did you know that certain foods block calcium absorption?

Self Care, Diet and Nutrition

 

You try to eat a healthy, calcium-rich diet. You watch your weight. You exercise. You do everything in your power to maintain strong bones because you want to be active well into your 70s and 80s.

You even make sure you have a nutritious breakfast of natural whole wheat squares topped cold, vitamin-D-fortified milk.

It sounds like a nutritious way to your day. But eating whole-wheat cereal and milk together may not be the best menu choice if you are trying to increase your bone mass. There are certain foods, like wheat, that block calcium absorption.

 

Phytates bind calcium.

High-fiber foods contain phytates, which prevent the body from absorbing calcium in other foods. Eating a high-fiber, whole-wheat cereal with milk, macaroni and cheese, or drinking a tall, cold glass of milk with Boston baked beans and hot dogs may be great-tasting combinations, but they do not boost bone-building nutrition.

Phytates found in whole-grains, legumes (dried beans), nuts and soy products bind the calcium of other foods eaten when they are eaten at the same time. When calcium is bound, the body cannot use it.

 

Oxalic acid hinders calcium absorption.

Foods high in oxalic acid also impede the absorption of calcium by binding the mineral.

Spinach is naturally high in calcium, but it is also high in oxalic acid. The body is unable to process the calcium it provides. Other foods that contain oxalic acid include beet greens, rhubarb and sweet potatoes.

Though these foods should not be considered for their calcium value, they do provide other nutrients and minerals that help the body stay healthy.

 

Does protein interfere with calcium absorption?

Historically, nutritionists have warned that eating large amounts of protein causes the kidneys to flush calcium out of the body. But recent studies show protein also may increase intestinal calcium absorption.

More study is needed to determine protein’s effect on the body’s ability to process calcium. To make the most of your calcium intake, don’t drink milk with your beef stew, chili or steak dinner. Eat your meal and then drink your milk later. 

 

Beer, cheese and snacks are a trifecta for calcium loss.

Alcohol and salty foods are catalysts for calcium flushing. As calcium levels in the blood decrease, the body extracts (resorbing) calcium from the bones to obtain the calcium it needs to function properly. Calcium flushing can make the bones porous, which can lead to the development of osteoporosis.

To minimize calcium flushing:

  • Avoid eating foods that have a sodium content higher than 20 percent of the daily recommended value.
  • Don’t drink more than two or three alcoholic drinks a day.

 

You can eat your spinach and build your calcium, too.

Wheat and other “bad-to-the-bone” foods provide many other vitamins and minerals vital to your health. You should still eat these types of foods, just not at the same time that you drink milk or eat calcium-rich foods.

The best way to maximize the nutrition from foods that bind or flush calcium and continue to boost your calcium levels is just a matter of scheduling. Eat calcium-binding foods at least two hours before or after you eat calcium-rich foods. This timing allows your body to maximize the vitamins and minerals of all food types. By making this timely adjustment to your meals, you gain all the nutritional benefits without interfering with your body’s ability to absorb the calcium it needs every day.

Source:
 The National Institutes of Health Office of Dietary Supplements

 

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Calcium Absorption – an overview

Intestinal Calcium Absorption

Calcium absorption is moderately efficient in humans, with 35% of dietary intake typically absorbed. The transfer of calcium across the intestinal barrier occurs through both saturable (presumably transcellular) and nonsaturable (presumably paracellular diffusion) pathways. Calcium absorption is saturable in the duodenum (proximal segment of small intestine) and to a lesser extent in the jejunum (midportion of the small intestine). Animal studies suggest that saturable calcium transport may also occur in the large intestine. The saturable pathway is energy dependent. Calcium moves from the mucosal to serosal side of the intestine, even against a concentration gradient. This pathway is under nutritional and physiologic regulation. For the standard recommended calcium intake (i.e., 400–500 mg per meal), the saturable transport accounts for more than 60% of total calcium absorption in the small intestine, thus demonstrating the importance of the saturable calcium absorption pathway under normal dietary loads.

In contrast, passive transport, involving claudins-2, -12, and -15, occurs throughout the entire intestine. Passive transport is a nonsaturable, linear function, dependent on the calcium concentration found in a given segment of the intestinal lumen.

When calcium intake is adequate to high, the proportion of calcium transported in any given intestinal segment is determined by the following: (1) the presence of saturable and nonsaturable pathways, (2) the transit time through the intestinal tract, and (3) the solubility of calcium within the intestinal segment. As a result, even though calcium solubility is low and the saturable pathway is absent or downregulated in the ileum (the final segment of the small intestine), the total amount of calcium absorbed is actually greatest in the ileum because transit time through this segment is 10 or more times longer than through the more proximal intestinal segments.

Habitual consumption of a low-calcium diet stimulates processes to increase small intestine calcium absorption efficiency. This effect is mediated in part through changes in the plasma concentrations of the most active vitamin D metabolite, 1,25(OH)2D. There are four different models for regulated calcium transport (Fig. 13.3).

Figure 13.3. Intestinal calcium absorption. Passive paracellular transport following the concentration gradient involves claudin-2, claudin-12, and claudin-15. Although passive, this process can be regulated by 1,25(OH)2D and prolactin through changes in gene transcription. Active transport may occur through multiple mechanisms: facilitated diffusion, vesicular transport, and transcaltachia. Facilitated diffusion (middle right, middle left) uses the transient receptor potential cation channel subfamily V member 6 (TRPV6), calbindin-D9K, basolateral transport via plasma membrane Ca2+ ATPase 1 (PMCA1), and the sodium-calcium exchanger 1 (NCX1). Gene transcription for expression of these proteins is upregulated by 1,25(OH)2D. Transcaltachia (lower left) refers to the rapid action of 1,25(OH)2D on either a membrane form of the vitamin D3 receptor (VDR) or membrane-associated, rapid-response steroid-binding protein (MARRS), triggering a rapid increase in transport through TRPV6 or through lysosomal cycling, independent of gene transcription. Vesicular transport (lower right, lower left) occurs through endocytosis or entry of cytoplasmic calcium into vesicles for transport and basolateral exocytosis.

In the facilitated diffusion model, calcium enters epithelial cells through the apical membrane calcium channel TRPV6. TRPV6 delivers calcium to calbindin-D9K, a low molecular weight, cytosolic, calcium-binding protein proposed to facilitate transcellular calcium movement. Calcium is then actively extruded across the basolateral membrane. This is primarily mediated by PMCA1b moving calcium against a concentration gradient, though the NCX1 sodium-calcium exchanger also contributes. Each of these proteins are transcriptionally regulated by 1,25(OH)2D.

The validity of the facilitated diffusion model has been challenged. Animals lacking TRPV6 or calbindin-D9K still increase the efficiency of intestinal calcium absorption in response to dietary calcium restriction, and 1,25(OH)2D still increases calcium absorption in TRPV6 knockout mice. Furthermore, mice without calbindin-D9K have normal calcium absorption, both at baseline and in response to 1,25(OH)2D. However, mice with the combined knockouts of TRPV6 and calbindin-D9K have a limited response to 1,25(OH)2D. These studies suggest that other mechanisms in addition to facilitated diffusion contribute to the process of active calcium transport across enterocytes.

The vesicular transport model predicts that calcium absorption required cycling of calcium-containing lysosomes in enterocytes (as in Fig. 13.3). In enterocytes, 1,25(OH)2D increases both lysosomal number and calcium content. Lysosomal calcium uptake models occurring after TRPV6 transport and endocytosis into cells have been proposed. Transient receptor potential cation channel subfamily V member 5 (TRPV5) and TRPV6 may be present in some vesicular structures and facilitate calcium transport. Enterocyte vesicle calbindin-D28K is also reported in chicks. However, it is not clear whether calcium accumulation in vesicles is specific to mammalian transcellular calcium transport regulation.

Transcaltachia refers to a rapid, 1,25(OH)2D-stimulated increase in calcium transport (Fig. 13.3). In contrast to the facilitated diffusion model, transcaltachia does not require gene transcription, although, like in the vesicular transport model, transportation across the cell may still involve vesicles. In ex vivo perfused chick intestine, exposure to 1,25(OH)2D for 14 min dramatically increases calcium transport across enterocytes.

Transcaltachia appears to be mediated by a basolateral membrane receptor: either by a unique role for the vitamin D3 receptor (VDR) at the basolateral surface, by a novel membrane vitamin D receptor called the membrane-associated, rapid response steroid-binding protein (MARRS), or by the PTH-PTHrP receptor. However, MARRS knockout mice do not have disrupted transcellular calcium absorption or whole body calcium metabolism.

Regulated paracellular transport also contributes to calcium absorption. 1,25(OH)2D increases production of the tight junction proteins claudin-2 and claudin-12 in the jejunum and ileum facilitating passive transport. However, vitamin D regulates active calcium absorption in the proximal duodenum and jejunum, as opposed to the ileum, where claudin-2 and claudin-12 expression is highest. Prolactin upregulates claudin-15 during pregnancy and lactation, contributing to paracellular calcium absorption, as well as TRPV5, TRPV6, and calbindin-D9K also upregulating transcellular calcium transport. In addition, the voltage-dependent L-type calcium channel subunit alpha-1D (also known as voltage-gated calcium channel subunit alpha Cav1.3) may also contribute to intestinal calcium absorption. However, this protein’s gene is not vitamin D regulated and Cav1.3 knockout mice do not have strong disruptions in either calcium or bone metabolism.

In sum, no single model is able to explain fully intestinal calcium transport mechanisms and the timing of responses to 1,25(OH)2D. Data support both transcriptional and more rapid responses of calcium transport to 1,25(OH)2D; more rapid increases in calcium transport suggest that mechanisms such as vesicular transport may be important. Redundancy in this system likely enables greater control and efficiency of calcium absorption, given that relative dietary deficiency is common and excess calcium consumption can also occur. Further studies are necessary to delineate the relative contributions of these various models and their mechanisms.

Vitamin D, calcium homeostasis and aging

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    90,000 How do you get your calcium intake and help your body absorb it properly?

    Calcium is found in many foods. But simply eating them to provide calcium is not enough. This macronutrient is pretty moody. It is difficult to digest, requiring special conditions for this. If we do them, we will get strong bones and healthy teeth and beautiful hair.

    Calcium is not at all alone. In order for it to be assimilated in the body, it needs companions.Magnesium and phosphorus are best suited. If these substances are enough (which by the way is rare), then calcium will be assimilated. But if magnesium, for example, is in short supply, then calcium, on the contrary, will be intensively excreted from the body. In order to prevent such a development of the plot, it is worth eating cottage cheese more often. It contains all the participants in this game: calcium, phosphorus, and magnesium. Alternatively, eggs, fresh herbs, and certain types of fish are good options.

    Legumes are also a good option for getting your calcium requirement.Soups made from peas or chickpeas, beans and tofu contain calcium, magnesium and phosphorus in the required proportions. You can also get additional magnesium from whole grain bread or cocoa.

    Product selection

    Milk and dairy products contain calcium in the form of lactate. It is easy to digest and almost completely fulfills its purpose. Slightly worse, by 80 percent, citrate and similar calcium compounds from broccoli, collard greens (except spinach), almonds, turnips and fish are absorbed.But sesame is full of easily digestible calcium. Having eaten 100 g, you can supply your body with a daily norm.

    But this does not mean that from now on sesame must be eaten with spoons. You can add it to leafy greens and broccoli salads with cottage cheese, or drink a tablespoon of sesame oil in the morning on an empty stomach. And as a dessert, eat figs and almonds.

    Chia seeds are also rich in calcium. 100 grams contains about 600 mg of an important macronutrient. Chia seeds can be conveniently added to smoothies, desserts, or yogurt.

    By the way, calcium is also found in large quantities in plant milk, especially oat milk. There is 120 mg of calcium per 100 ml. It can be added to hot and cold drinks, used as a smoothie base, or cooked into porridge.

    Avoid Waste

    Choosing the right calcium-rich foods is only half the battle. At the same time, it is better to exclude foods that contribute to its loss from the diet. The macronutrient is washed out under the influence of caffeine, salt and hydrogenated fats.In this regard, it is better to avoid eating margarine, creamy spreads and canned sauces. As for coffee, you can, of course, drink it, but no more than 3 cups a day. If you can’t meet this amount, then at least compensate for the losses with additional milk.

    Beets, spinach, sorrel and rhubarb, or rather the acids they contain, will interfere with the absorption of calcium. They should be consumed in moderation. But dried apricots, on the contrary, should be added to the diet.It contains potassium, which will prevent the loss of an important macronutrient.

    Conductors for calcium

    It is possible to increase the absorption of calcium. For example, if you use it together with vitamin D. It not only increases the absorption of the microelement by 30-40%, but also normalizes its balance with phosphorus. In addition, vitamin D is actively involved in calcium metabolism.

    Highest vitamin D content in liver, eggs and seafood. Such as shrimp, lobster, crabs, herring, salmon, sardines and mackerel.But we get all such main amount thanks to ultraviolet rays. Therefore, on a sunny day, be sure to walk in the fresh air for at least a quarter of an hour.

    Physical activity

    Calcium will be absorbed much better if we have enough physical activity in our lives. If you run or walk, do exercises with a barbell or dumbbells, then the bone tissue will grow.

    And you shouldn’t even sweat to a sweat. Because with sweat, the loss of calcium only increases.It is enough to lose 400-450 kcal during the lesson. Typically, a standard power set and thirty minutes of cardio will suffice for this. The sauna should not be overused. And if you still sweat, then make up for the loss with a glass of kefir or oat milk with the addition of chia seeds.

    Supplements for sports and beyond

    Even if you do not exercise professionally, pay attention to whey protein isolate. It contains not only essential amino acids, but also bioavailable calcium.

    It is believed that after 25 years, 800 mg of calcium should be consumed per day. And after 50 and even more – 1200-1500 mg, as well as for pregnant and lactating women. In addition, American scientists also advise adding 100 mg of vitamin B6 and 400 mg of magnesium oxide to your daily diet. It improves mood and helps to flush excess water from the body.

    Minimum stress

    When we are nervous, our body produces the stress hormone cortisol. It negatively affects the absorption of calcium in the intestine and promotes its excretion in the urine.Therefore, the more stress we experience, the more calcium we lose.

    Remember this and try to avoid unnecessary worries. Allow yourself to rest and eat well. And do not deprive yourself of the joys in the form of a piece of dark chocolate. It contains antioxidants, vitamins A, C, E, as well as selenium, magnesium, iron, potassium and calcium, of course.

    Useful calcium

    We tend to think about a lack of calcium when external reasons for concern appear: dental problems, hair loss, peeling and brittle nails.But do we know everything about him?

    Calcium is necessary not only for the tissues of teeth and bones, it also affects many metabolic processes in the body. Therefore, signs of calcium deficiency are not only brittle nails, problems with tooth enamel, hair, but also tingling in the fingers, numbness of the limbs and cramps.

    The problem with calcium is that it is difficult to assimilate. Even with the use of milk, fish and vegetables, only 25-30% will be assimilated. It is extremely difficult to replenish the daily supply of calcium through food alone.Biologically active additives are an additional source of calcium.

    1

    The highest concentration of the basic substance is found in supplements containing calcium carbonate. It is also necessary to look for it in the composition of the drug.

    2

    The best “allies” of calcium are vitamin D3 (cholecalciferol) and vitamin C. The first will help calcium to be absorbed in the body, the second for additional strengthening of the walls of blood vessels.

    3

    In order for calcium to have a beneficial effect on the body, vitamin K is added to the vitamin complexes.It helps direct calcium to its destination, namely bones, hair, nails and tooth enamel. And vitamin B6 reduces the excretion of calcium from the body.

    There are innumerable amounts of vitamin complexes with calcium on the market today. You can choose for every taste: for children and for pregnant women, for the elderly and for general use, foreign and Russian. How to choose a really good product in such a variety? You need to pay attention to the composition. It is important that for better absorption of the vitamin complex with calcium there are all the trace elements mentioned above, namely vitamins C, B6, D and K.

    These parameters correspond to the Multivita Calcium plus complex in the form of effervescent tablets. A significant advantage of this product is the absence of sugar in the composition, therefore, it is included by the Russian Diabetes Association in an expanded assortment list of goods for a healthy lifestyle and for the nutrition of consumers with diabetes mellitus. And due to the release form, it is convenient for taking, especially by elderly people: 1 tablet must be dissolved in a glass of water at room temperature.

    Dietary supplement Vitamir Calcium D3 chewing with orange flavor 100 tablets

    In the dietary supplement “VITAMIR D3 Calcium with orange / lemon / mint flavor” calcium is present in the form of carbonate, it contains 40% elemental calcium.In addition, the dietary supplement contains vitamin D3 (cholecalciferol), which significantly increases the absorption of calcium, normalizes the formation of the bone skeleton and teeth in children, and helps to preserve the structure of bones.

    Ingredients: active ingredients: calcium carbonate – 1250 mg (equivalent to elemental calcium – 500 mg), vitamin D3 (cholecalciferol equivalent to -2.5 μg (100 IU)), auxiliary components: sucrose, talc (anti-caking agent), calcium stearate (anti-caking agent), potato starch, natural orange / lemon / mint flavor.

    Information on biologically active substances and their properties:

    • Calcium (Ca) is a common macronutrient in the human body, which is the main building material of bones (99% of calcium is contained in bones), teeth, an important component of hair and nails. Also, calcium ensures the normal functioning of the body as a whole.
    • Calcium requirements may vary at different times in life. For example, in adolescence, the consumption of a sufficient amount of this element is very important due to the intensive growth of the skeleton, for example, with a lack of calcium, children begin to lag behind in growth.
    • During menopause and postmenopause, calcium helps prevent fractures, this is especially important for those who are not receiving hormone replacement therapy.
    • Reduced bone density can result in joint pain, and in older people, increased bone fragility increases the risk of fractures. With an increase in calcium deficiency, the mineralization of bone mass decreases, which can lead to a pathological decrease in bone density, its rarefaction with a loss of natural strength.
    • In the human body, calcium deficiency can manifest itself in the form of deterioration of the condition of teeth, hair and nails, as well as increased fatigue, general weakness and a decrease in the usual ability to work. At the same time, muscle spasms, nervousness, irritability can be observed.
    • The key role of vitamin D3 , included in VITAMIR calcium D3″ is to maintain calcium-phosphorus balance in the blood. Vitamin D3 is important for the normal absorption of calcium in the intestines, as well as for maintaining the strength of teeth and bones.

    Scope: as a biologically active food supplement – an additional source of calcium, vitamin D3.

    BAA, is not a drug.

    Contraindications: individual intolerance to the components.

    Before use, it is recommended to consult a doctor, before using dietary supplements for children, it is recommended to consult a pediatrician.

    With caution: persons with dental inserts in the oral cavity (braces, dentures) – due to their possible damage.

    Method of administration and dosage: children 3 – 7 years old, 1 tablet a day with meals; children over 7 years old – 1 tablet 2 times a day with meals; adults 1-2 tablets 2 times a day with meals. Duration of admission is 1-2 months. If necessary, the reception can be repeated.

    Storage conditions: in a dry, dark place, out of reach of children, at a temperature not exceeding 25 ° C.

    Expiration date: 3 years.

    CALCIUM D3 VITAMIR N30 JEW TAB WITH ORANGE TASTE

    In the dietary supplement “Calcium D3 VITAMIR® with orange flavor” calcium is present in the form of carbonate, it contains 40% elemental calcium.

    In addition, the dietary supplement contains Vitamin D3 (Cholecalciferol), which significantly increases the absorption of calcium, normalizes the formation of the bone skeleton and teeth in children, and helps to preserve the structure of bones.

    Calcium (Ca) is a common macronutrient in the human body, which is the main building material of bones (99% of calcium is found in bones), teeth, an important component of hair and nails. Also, calcium ensures the normal functioning of the body as a whole.

    Calcium requirements depend on age. With an increase in calcium deficiency, the mineralization of bone mass decreases, which can lead to a pathological decrease in bone density, its rarefaction with a loss of natural strength.

    In adolescence, the intake of sufficient amounts of calcium is very important due to the intensive growth of the skeleton, for example, with a lack of calcium, children begin to stunted.

    During menopause and postmenopause, calcium is essential to prevent fractures, and especially for those who are not receiving hormone replacement therapy.

    Joint pain can occur as a result of decreased bone density, and in older people, increased fragility of bones increases the risk of fractures in typical places: the wrist joint, vertebral bodies or the femoral neck.

    In the human body, a lack of calcium can manifest itself in the form of deterioration of the condition of teeth, hair and nails, as well as increased fatigue, general weakness and a decrease in the usual ability to work.At the same time, muscle spasms, nervousness, irritability can be observed.

    1 tablet contains:

    Calcium 500 mg

    Vitamin D3 5 μg (200 IU)

    Nutritional and energy value 100 g: fats – 1 g, carbohydrates – 24 g, calories 104 kcal (435 kJ).

    Calcium – Impact of Protein Intake and Vegan Research

    I am posting the penultimate part of the article about vitamin D and calcium.This section discusses how protein intake affects calcium absorption and how much protein is involved in leaching calcium out of bones. Also discussed is a study conducted by the University of Oxford, which showed that the incidence of bone fractures in vegans was 30% higher than in groups of people who eat other types of food. To find out why they had more fractures, see cat.

    This google dox document can be found here. Tomorrow, I will be exhibiting the last part of this article, which will show a chart of plant foods for the richest in calcium and give tips on how to meet your calcium needs in a vegan diet.So don’t miss the next and final episode! 🙂

    Proteins

    As mentioned above, there is a theory according to which proteins, especially sulfur-containing amino acids, increase the acid load in the body, thereby provoking the excretion of calcium in the urine. Sulfur-containing amino acids predominate in animal products, although they are also found in high amounts in many cereals. Another theory, in contrast, claims that proteins increase the absorption of calcium in the intestinal system, which in turn neutralizes the loss of calcium in the urine (29).

    In the 2004 summer issue of Soy Connection magazine, an article was published on this topic, titled “Are Protein and Calcium Friends or Foes?” It concluded:

    Recent evidence suggests that high protein intake does not necessarily have a negative effect on bone health. Protein source composition and other dietary factors determine acid load. It appears that healthy people who eat high-protein foods in the context of a typical diet do not reach the point where calcium homeostasis (balance) is disturbed.

    In December 2009, a meta-analysis of studies examining bone health and protein intake was published in the American Journal of Clinical Nutrition (33). It included seven cohort studies analyzing protein intake and fracture risk. The meta-analysis concluded:

    The bulk of the evidence suggests that protein intake has little or no positive effect on the skeleton.However, the long-term clinical effect is not yet fully clear. There was also no reduction in fracture risk. More research is needed to resolve the controversy over the effects of protein intake on bone health. In the meantime, when planning a healthy diet, you can rely on the quantitative recommendations for protein intake and balancing different protein sources provided in the government’s healthy eating guidelines.

    It is possible that a protein intake of two to three times the daily intake may increase the risk of osteoporosis.However, research shows that for ovo-lactic vegetarians and non-vegetarians, animal protein does not pose a significant threat to bone health.

    Vegan Studies

    Very little data exists to date on the health of vegans. Several small cross-sectional studies have shown that vegans have the same or slightly lower bone density than non-vegans (9-12, 13, 30). These studies were conducted with vegans who may not have been getting enough vitamin D or trying to meet the recommended calcium intake.

    In 2009, researchers from Vietnam and Australia conducted a meta-analysis of studies examining bone density among vegetarians (23). They concluded: “Vegetarian and especially vegan diets have little effect on bone density. In addition, it is unlikely that this impact will lead to clinically important changes in the risk of bone fractures. ”

    In 2007, published the first study discussing fracture risk among vegans (14).For EPIC-Oxford, the study recruited 57,000 participants, of whom over 1,000 were vegans and nearly 10,000 ovo-lactic vegetarians. The study was conducted from 1993 to 2000. At the beginning, participants were asked to fill out questionnaires to find out what they eat. Five years after the start of the study, participants were sent out new questionnaires asking about any fractures that have occurred in the past five years (to be paraphrased).

    After scientists adjusted the study for age, the incidence of fractures in vegans was 37% higher than in non-vegetarians.After adjusting for age, smoking, alcohol consumption, body weight, physical activity, marital status, number of births, and hormone replacement therapy, vegan fracture rates were still 30% higher than meat eaters. The incidence of fractures in non-vegetarians, sand vegetarians, and ovo-lacto vegetarians did not differ in all analyzes.

    However, there was some good news in this study. After adjusting the study results for calcium intake, vegans lost the lead in fracture rates (paraphrase?).Among participants who consumed at least 525 mg of calcium per day (only 55% of vegans and 95% of those on other diets), the incidence of fractures in vegans was the same as in non-vegans.

    Does this mean that insufficient calcium intake is the cause of fractures? It is possible that participants who consumed more calcium also consumed more or less vitamin D or protein. However, the authors noted that the incidence of fractures was not associated with protein or vitamin D intake.A separate analysis of the EPIC-Oxford (20) study found that calcium intake was associated with an increased risk of fractures for women but not for men. The relative risk averaged 1.75 (1.33-2.29) for women who consumed less than 525 mg per day compared to women who consumed more than 1200 mg per day.

    Today, we have to assume that vegans with a lot of fractures were lacking calcium.

    Tags: veganhealth

    90,000 TOP-11 calcium preparations – rating of good products 2021

    Calcium is one of the electrolytes in the body.It is a mineral that carries an electrical charge when dissolved in blood. The role of calcium in the body can hardly be overestimated, since it is a building material for bone structures, maintains the health of cell membranes and takes part in the transmission of nerve impulses. Also, calcium has a detoxifying, anti-inflammatory and anti-allergenic effect.

    About 99% of the calcium in the body is stored in the bones. However, cells (especially muscle cells) and blood also contain calcium.Calcium is needed for:

    • the formation of bones and teeth;
    • muscle contractions;
    • blood clotting;
    • maintaining the functions of enzymes and hormones;
    • ensuring a normal heart rate.

    The body precisely controls the amount of calcium in cells and blood. As needed, the mineral is transferred from the bones to the blood to maintain a constant balance.When people don’t get enough calcium, calcium is taken from the bones, which weakens them. Osteoporosis can be the result. To maintain normal blood calcium levels without weakening bones, you need to consume at least 1000-1500 mg of calcium per day. This requires a balanced diet or medication.

    The best calcium supplements are presented in the ranking below. The TOP is compiled depending on the effectiveness and safety of medicines, as well as on the basis of reviews.An equally important criterion is the price-quality ratio. Finding a medicine on your own is not easy. To begin with, you should consult a doctor and, if necessary, undergo an examination to clarify the diagnosis.

    Classification of calcium preparations

    Calcium deficiency often creeps up and then goes unnoticed for a long time. This condition can have a negative impact on bone health. Thus, the risk of developing osteoporosis and bone fractures increases.

    In the presence of a significant deficiency, the following symptoms are possible:

    • tingling in the limbs;
    • muscle twitching;
    • cramps and numbness;
    • excessive anxiety;
    • deterioration of the condition of the skin and hair;
    • excessive brittleness of the nails;
    • periodontal disease and caries;
    • increased heart rate;
    • disorders of digestive functions.

    Experts recommend that calcium supplements only be taken if there is a proven deficiency of this mineral and vitamin D, or if there is existing osteoporosis. The main thing is to choose the right drug and dosage.

    Calcium preparations are classified as follows:

    • Lactate. Absorbed by the body at any pH value. Can be taken regardless of food intake. This pharmacological group successfully neutralizes the insufficient effect of estrogen-containing drugs.As monotherapy, it does not allow to replenish the calcium requirement.
    • Gluconate. It is used as a topical agent or as a solution for injection. The drugs included in this group physiologically stimulate the release of the active form of the calcitonin molecule. It has a positive effect on kidney function, providing a natriuretic and vasodilating effect. Calcium gluconate is a safe and effective form of calcium that can be used to increase bone density in premature babies.
    • Citrate. An exceptional form of calcium that is the most effective and safest. The advantage is complete dissolution in water and assimilation, regardless of the acidity of the gastric juice and food intake. Calcium citrate is the drug of choice for people with low gastric acidity and elderly patients who are taking proton pump inhibitors and antacids. Also, this group of calcium preparations helps dissolve kidney stones.

    Less safe are inorganic calcium salts: phosphate and carbonate.Calcium carbonate antacid may not be completely absorbed by the body, which depends on the acidity of the gastric juice and the general condition of the gastrointestinal tract. Phosphates are also practices that completely neutralize acid, therefore, they have a number of contraindications for use.

    Causes of calcium deficiency in the body

    To properly perform its various tasks, calcium must be present in the body in sufficient quantities. But what is enough? Daily requirements vary according to age group.Unlike many other nutrients, your need for calcium is not sex-specific. Men and women need the mineral equally.

    Table – Daily calcium requirement depending on age

    Age group

    Calcium amount, mg / day

    1 to 4 years old

    600

    4-7 years old

    750

    7 to 10 years old

    900

    10 to 15 years old

    1100

    15 to 19 years old

    1200

    19 years and older

    1000

    Pregnant and lactating women

    +100

    It is not only amazing that men and women need the same amount of calcium.In addition, the fact that the need of pregnant and lactating women is practically not increased, distinguishes calcium from other nutrients. However, women should individually coordinate their nutritional needs with an obstetrician to rule out deficiencies.

    Given the basic functions that calcium takes on in the body, it is clear that a deficiency in minerals can seriously affect health.

    Among the main causes of deficiency states are:

    • Monotonous food.Calcium is present in sufficient quantities, primarily in dairy products of animal origin. Mineral deficiency is diagnosed primarily in vegans and people with lactose intolerance.
    • Disorders of the gastrointestinal tract. For digestive disorders associated with problems such as vomiting, nausea, bloating, and diarrhea, absorption of nutrients may be difficult or prevented.
    • Kidney disease (kidney failure).Reduces the excretion of the mineral phosphate. Although phosphate is not actually harmful to the body, an increased concentration can alter calcium levels in the body. As a result, a deficiency state develops.
    • Thyroid dysfunction (hypothyroidism). The thyroid gland produces a hormone that regulates calcium balance. With inflammation of the pancreas, the function of assimilating nutrients from food is disrupted. Therefore, as a consequence of this disease, the absorption of calcium is also impaired.

    Diuretics can cause calcium deficiency. Medicines of this group are used for renal failure, as well as for liver diseases, edema, hypertension and heart failure.

    With age, the performance of our digestive system decreases. As a result, it becomes more difficult for the body to release and absorb nutrients from food. However, older adults are at a particularly high risk of developing calcium deficiency. Bone substance also weakens with age.

    Vitamin D deficiency is one of the most common causes of calcium deficiency. As we already know, it is absorbed mainly in the intestines. Vitamin D (cholecalciferol) promotes absorption from the small intestine and the incorporation of calcium into bones. Thus, vitamin D plays a crucial role in calcium absorption.

    Vitamin D is, in fact, not a vitamin at all, but a precursor to a hormone that the body can produce itself. The main requirement for this is sunlight, because exposure to ultraviolet rays on the skin leads to the formation of vitamin D, and then further processes in the kidneys and liver to produce an effective substance called calcitriol.

    It is already reliably known that 91% of women and 82% of men are insufficiently provided with vitamin D. Therefore, regular consumption of foods rich in vitamin D is strongly recommended. But, as practice shows, in most cases this is not enough to fill deficiency states. In this case, good calcium tablets are needed.

    Rating of calcium preparations

    First, it is recommended to normalize the power supply. The most famous calcium-rich foods are milk and dairy products.Already 200 ml of cow’s milk provides about 240 mg of calcium and thus covers almost of the daily calcium requirement. By the way, the fat content of milk does not matter, it does not affect the mineral content.

    Cheeses, especially hard varieties such as Parmesan or Tilsit, are especially rich in calcium. For example, 30 g of Tilsit provides about 250 mg of calcium.
    But even through herbal products, we can meet our calcium needs. Recommended especially:

    • green leafy vegetables such as cabbage, arugula or fennel;
    • herbs such as parsley or dill;
    • nuts and seeds also contribute to the targeted supply of calcium.

    Many people are unaware that mineral water can also be a good source of calcium. Mineral waters can contain more than 500 mg / l of this mineral. From 150 mg calcium / liter, mineral water can be said to be rich in calcium.

    Medicines and dietary supplements are rich sources of calcium. To achieve the result declared by the manufacturer, you must strictly follow the instructions for use.

    TOP-11 calcium preparations

    From this list you can choose the most suitable one:

    No. 1 – “Calcium-D3 Nycomed” (Takeda, Russia)

    Combined preparation based on calcium carbonate.The clinical and pharmacological group is aimed at regulating the exchange of phosphorus and calcium in the body. Chewable tablets improve the condition of nails, hair, teeth and muscle structures. Available with lemon, orange, mint and strawberry-watermelon flavors 60 and 120 pcs.

    “Calcium-D3 Nycomed” is included in the list of the best calcium preparations, since it increases bone density and replenishes the lack of vitamin D3 in the body. As a result, nerve conduction improves, muscle contractions are normalized and blood clotting indicators are normalized.The drug is widely used during growth, pregnancy and lactation, excluding deficiency conditions.

    No. 2 – “Calcium Magnesium plus zinc” (Solgar, USA)

    Biologically active food supplement, which is an additional source of minerals:

    • calcium – maintains the strength of bone structures;
    • magnesium – ensures an even distribution of calcium throughout the body and promotes its absorption;
    • zinc – takes part in the production of its own collagen in bone structures.

    The tablets are in second place in the ranking of calcium preparations due to the fact that the combination of minerals is presented in a special chelated form. The active substances are absorbed by the body as much as possible.

    No. 3 – Calcemin Advance (Bayer, USA)

    The drug belongs to such a pharmacotherapeutic group as a calcium-phosphorus metabolism regulator. The composition includes micro and macro elements, as well as vitamins. The action of the tablets is due to the properties of the active ingredients:

    • forms bone tissue, increasing its density and reducing resorption;
    • prevents the development of diseases of the musculoskeletal system;
    • strengthens the skeletal system and articular structures.

    Calcium citrate is absorbed regardless of the secretory functions of the gastrointestinal tract. Thanks to vitamin D3, mineral metabolism in the body is regulated.

    It is prescribed for the prevention and complex treatment of osteoporosis in women in menopause, with the use of immunosuppressants and glucocorticosteroids, as well as in the treatment of various diseases of the musculoskeletal system. Also, the drug “Calcemin Advance” is indicated for adolescents to replenish the deficiency of trace elements in the body.

    No. 4 – Calcemin (Bayer, USA)

    The regulator of calcium-phosphorus metabolism. The drug “Kalcemin” is developed on the basis of calcium, vitamin D3 and osteotropic minerals that regulate metabolic processes.

    The action of film-coated tablets is due to the active ingredients:

    • calcium – forms bone tissue, increasing and preventing disorders of the musculoskeletal system;
    • colecalciferol – preserves the structure of bones, improves the absorption of minerals in the intestinal area;
    • zinc – synthesizes sex hormones, preventing the destruction of bone structures;
    • copper – synthesizes elastin and collagen, normalizing the formation of bone mass;
    • manganese – forms proteoglycans that form a protein matrix.

    Not recommended for hypercalcinuria and hypercalcemia, in case of vitamin D3 hypervitaminosis, nephrolithiasis, severe renal failure. Among the absolute contraindications, one should highlight the active form of tuberculosis, children under 5 years of age and decalcifying neoplasms.

    If you do not know which calcium tablets to choose for pregnant women, then “Calcemin” is the most suitable option. A preliminary consultation with an obstetrician-gynecologist leading a pregnancy is mandatory.

    No. 5 – “Calcium Citrate + Vitamin D / Calcium Citrate + D” (Alpha Vitamins Laboratories, USA)

    The drug is developed on the basis of minerals and is intended for the prevention and complex treatment of idiopathic, steroid or postmenopausal osteoporosis. It is used for complications such as bone fractures, and is also prescribed for the elimination of deficiency conditions.

    Recommended to be taken when the body’s need for vitamin D3 and calcium is increased, for example during pregnancy and lactation, as well as in childhood and adolescence during periods of intensive development.

    No. 6 – Complivit Calcium D3 (Pharmstandard-Leksredstva, Russia)

    Orange flavored chewable tablets regulate the mineral and vitamin balance, improving the condition of muscle and bone structures. The drug effectively copes with osteomalacia associated with impaired mineral metabolism in people aged 45 and older.

    Recommended to be taken from the age of 12, swallowed or chewed whole. Adverse reactions include hypercalciuria and hypercalcemia, diarrhea, pain in the abdomen or stomach, and allergic reactions.

    No. 7 – “Calcium gluconate” (Renewal, Russia)

    The tablets are designed to replenish the mineral deficiency in the body. Formulated on the basis of calcium gluconate monohydrate. The active substance is involved in the formation of bone tissue and in the process of blood coagulation. It is used to support cardiac activity and improve the transmission of nerve impulses.

    The drug “Calcium gluconate” improves the contractile activity of muscle structures, helping to cope with myasthenia gravis, muscular dystrophy and increased vascular permeability.The effect is achieved by stimulating the sympathetic nervous system and enhancing adrenaline secretion by the adrenal glands. The tablets have a moderate diuretic effect.

    No. 8 – “Vitamins” Calcium + Vitamin D “(PharmaMed, USA)

    Chewable lozenges contain natural vegetable and fruit extracts. Designed to enrich the child’s body with minerals and vitamins. The action is aimed at:

    • reducing the risk of caries development;
    • strengthening teeth and bones.

    It is prescribed for children aged 3 years and older, 1 lozenge 2 times a day. Children from 7 years of age and older – 2 lozenges 2 times a day. Recommended to be taken with meals.

    No. 9 – “Calcium 600 from oyster shells with D3” (Solgar, USA)

    It helps prevent calcium deficiency in children and adults, eliminating the development of rickets, osteolysis (destruction of bone structures), seizures and muscle spasms. It also eliminates the likelihood of diseases such as bowel cancer and high blood pressure, which are associated with a lack of calcium in the body.

    The course of treatment contributes to an increase in bone density and growth, the development and normal functioning of muscle structures. Calcium carbonate, obtained from oyster shells, protects bones and teeth from lead, a harmful metal that accumulates in the body during deficiency conditions.

    No. 10 – “Calcium D3” (Renewal, Russia)

    Chewable tablets are a biologically active food supplement, providing an additional source of minerals and vitamins.It is not recommended to take in the presence of individual intolerance, with renal failure and with an increased concentration of calcium and vitamin D in the blood or urine.

    No. 11 – “Doppelherz Active Magnesium + Calcium” (Queisser Pharma, Germany)

    Tablets are prescribed for increased physical and mental stress, as well as to reduce the risk of developing atherosclerosis and diseases of the cardiovascular system. Doctors recommend taking an additional source of minerals if you have an unbalanced diet and an unhealthy lifestyle.Among the absolute indications, one should highlight living in regions with a deteriorated environmental situation and frequent stressful situations.

    The effectiveness of the drug is due to its composition:

    • magnesium – improves the function of the heart muscle, restoring contractility;
    • calcium – normalizes blood clotting processes, takes part in the contraction of smooth and skeletal muscles, and also removes salts of radionuclides and heavy metals.

    The drug is intended for adults.It is recommended to take 1 tablet a day, unless otherwise prescribed by your doctor.

    Which drugs are absorbed better

    Calcium preparations are better absorbed if they are formulated on the basis of citrate. This compound is biologically very valuable and is a tool for delivering building material to bone structures. Calcium citrate is beneficial because it alkalizes urine, preventing the development of kidney stones and urinary tract infections.It also regulates energy metabolism and slows down the synthesis of parathyroid hormone, preventing the leaching of minerals from the body.

    But about 85% of the drugs on the pharmaceutical market are based on carbonate, which is less effective. But carbonic acid has its advantage, which lies in the high content of elemental calcium – more than 50%. But the carbonate, unfortunately, is absorbed only by 15-20%. And such drugs cause disorders of the gastrointestinal tract, which should be considered before use.This is due to the fact that when carbonic acid breaks down, carbon dioxide is formed, which is the cause of bloating.

    Due to the fact that the formation of bone structures obeys general biological laws, calcium is not the only necessary mineral for the processes to proceed continuously and in a reasonable ratio. It is important to restore the mechanisms of calcium metabolism before oversaturation of the body with calcium. To improve the processes of assimilation of minerals and their fixation in skeletal tissues, not only vitamin D3 is needed, but also B6 (thiamine).The complex effect allows you to achieve a more pronounced and lasting result.


    Conclusions

    The market for calcium-containing products is vast, but not many of the pharmaceutical diversity really deserve attention. This is due to the fact that not all pills are equally effective and safe.

    The rating of calcium supplements will help determine which of the presented funds is better. But it should be understood that a preliminary consultation with a specialist is the key to effective treatment and the exclusion of the likelihood of developing adverse reactions.It is possible to choose the best calcium in tablets only on the basis of the results of the diagnostic tests carried out. The doctor, when prescribing a particular drug, repels from the root cause of deficiency conditions, prescribing concomitant therapy to eliminate it.

    Prevention of hypocalcemia includes not only taking pills, but also a balanced diet, taking vitamin D3 and daily walks in the fresh air. Maintaining physical activity and practicing feasible sports are also important.

    Literature:
    https://www.vidal.ru/drugs/atc/a12ax
    https://www.lvrach.ru/2014/11/15436097
    https://cyberleninka.ru/article/n/sravnitelnyy -analiz-soderzhaniya-kaltsiya-v-kaltsiysoderzhaschih-f …
    https://www.vidal.ru/drugs/molecule-in/154

    Calcium and boron deficiency in plants. Consequences and methods of struggle

    For a plant to develop normally, it must receive all the necessary micro and macro elements. In nature, the balance of the required substances is not always achieved.But under artificial conditions, this is easy to achieve. The main thing is to responsibly treat the growing process and apply fertilizers in a timely manner. Which? We’ll cover in this article. But first, let’s decide what role calcium and boron play in plant life.

    The role of calcium in plant life

    Calcium is an essential element for proper growth and development. Mostly leaves. With its help, the exchange of proteins and carbohydrates occurs. It is part of the cell membrane and holds them together.

    Plants need calcium for the entire growing season. But the main requirement is its presence at the beginning of growth. This contributes to the correct construction and further development.

    The effectiveness of using this element depends on the type of soil, its acidity, the type of plants and weather conditions. Different species need this element in different ways.

    The effect of calcium on plants is manifested in the following:

    1. It has a positive effect on the development of the root system, regulates the water balance.
    2. Reduces soil acidity.
    3. Increases endurance and immunity to harmful organisms.
    4. Reduces the intake of radioactive elements, eliminates the negative effects of ammonia.
    5. Normalizes the acid-base balance in plant cells.
    6. Increases immunity to fungal infections.
    7. The liming of soils with a lack of calcium significantly improves its health. This increases air aeration and soil permeability.
    8. With its help, plants absorb the necessary nutrients better.

    Lack of calcium in plants

      The plant reacts very painfully to a deficiency of this element. Since calcium tends to accumulate in old parts and leaves, young leaves and shoots are most affected:

      • Plant cells are deformed. The stems become weak and hollow. They can crack easily.
      • Top leaves wither first.Their growth slows down, spots appear and they die off.
      • New leaves take on an ugly shape. They curl down, turn yellow, then fall off.
      • Roots gradually rot and die off. They become susceptible to root diseases.
      • A weak, drooping peduncle develops.

      Feeding plants with calcium will help to completely avoid such negative consequences. Next, we will consider with what fertilizers you can do this.

      How to make up for the lack of calcium in plants

      After the plant dies off, this element again enters the soil. Therefore, other plants get it as a result of the natural cycle. But if the soil for some reason is depleted in calcium, it is fertilized or lime.

      Enough calcium enters the soil with manure. Also, plants are sprayed with a solution of calcium nitrate or potassium chloride. But unknowingly, you can worsen the condition of the plants.Therefore, it is better to use high-quality, proven fertilizers. It is safer and easier to buy calcium for plants than to prepare it yourself.

      Let’s take a closer look at the best calcium fertilizers:

      Plagron Calcium Kick additive 5 kg. An excellent tool that improves the quality of the soil. With its help, the optimal pH level is established (5.5-6.5). It also improves the structure of the soil, accelerates the absorption of microelements. As a result, the plant develops faster.The soil in which Calcium Kick was applied can be reused. Only used in soil-based substrates.

      Set of mineral fertilizers Flora Series 3×60 ml. Fertilizers that will significantly increase yields. Using this kit, your plants will receive the care they need to thrive. Suitable for hydroponic and soil cultivation.

      Fertilizer set Plagron Top Grow Box Bio. A universal set for a beginner. It allows you to get beautiful, strong plants and an excellent harvest as quickly as possible.It includes all the supplements you need for successful cultivation. Can be used in any type of substrate, soil and hydroponics.

      Powder Feeding Calcium 1kg. This powder additive is used to enrich water with calcium. It strengthens your plant and protects it from pests. Suitable for use in soil and hydroponics.

      Mineral fertilizer FloraDuo Grow HW 500 ml. Fertilizer used in hard water.It develops and strengthens the root system well. Increases the absorption of essential elements. It is used in hydroponics and soil.

      Mineral fertilizer FloraMicro HW 1 l. Contains all the necessary micro and macro elements. It is applied using hard water. Stabilizes pH. Can be used for hydroponic and soil cultivation.

      The role of boron in plant life

      It is from this microelement that the quantity and quality of the crop most depends.Boron for plants is necessary for the entire growing season. The most in need of it is dicotyledonous plants, which absorb 10 times more boron than monocotyledons.

      Together with calcium, boron participates in the formation of cell walls. Therefore, it is necessary for the normal development of young parts. Lack of it at any stage of growth inevitably leads to disease.

      The effect of boron on plants is that:

      1. It accelerates the formation, movement and exchange of carbohydrates from leaves to roots.
      2. Improves photosynthesis, increases chlorophyll content.
      3. Positively influences the absorption of calcium.
      4. Promotes an increase in the number of flowers, fruits, pollen does not germinate without it.
      5. Increases resistance to bacterial and fungal diseases.
      6. Improves the growth of leaves, roots, buds. Increases the absorption of nutrients.

      Boron deficiency in plants

      Boron deficiency symptoms are similar to those of calcium.With a slight lack of it, plants can look healthy. But they will not bear fruit and bloom.

      At first, the problem manifests itself on young shoots and leaves. Wherein:

      • the upper part of the shoot is affected and dies off, the so-called. growth point;
      • small leaves grow, curl and fall off early;
      • the development of the upper kidneys stops, they gradually die off;
      • the stem is bent;
      • due to the growth of lateral shoots, the plant becomes like a bush;
      • flowers fall or there are no inflorescences at all;
      • the fruit does not set or has an ugly shape.

      How to Replenish Boron Shortage

      Boron is contained in the soil in the form of boric acid salts. When liming or washing out by precipitation, its content is significantly reduced. Therefore, fertilization of plants with boron is an important stage in their development.

      Do you want to significantly improve the quality of your crop? Use proven boron fertilizers:

      Fertilizer set Bio Sevia Bloom + Bio Sevia Grow 2×1 l.It is the first certified organic fertilizer for hydroponics. It is quickly absorbed by the plant, promotes increased absorption of nutrients. This unique product gives excellent results in soil and hydroponic cultivation.

      Mineral fertilizer 1 Component Soil Bloom B.A.C. 1 l. Fertilizer necessary during flowering. The solution prepared from it increases the immunity of the plant, strengthens the roots, accelerates the ripening of fruits. Suitable for use in soil.

      Powder Feeding Long Flowering 0.