B12 Side Effects and Interactions

Like all good things, too much of any vitamin or mineral can stir up trouble. Vitamin B12 is no exception and can cause side effects.

Vitamin B12 is essential for DNA production, red blood cell formation, DNA synthesis, and brain health. But if you take B12 supplements, you risk ingesting more B12 than you actually need. Here are the deets.

B12 supplements come in a variety of forms, including capsules, tablets, soft gels, gummies, and drops or sprays.

Taking these B12 supplements when you aren’t deficient may cause side effects like:

• nausea
• vomiting
• headache
• diarrhea
• tiredness
• feeling weak
• tingling or numbness in your extremities

If you notice any of these side effects, stop taking B12. And call your doc if anything gets worse.

While not fully proven side effects, research has also linked the following health risks to taking high dose B12 supplements when you aren’t deficient, like:

• Skin conditions. A 2015 research review linked taking too much B12 to acne, rosacea, vitiligo, and atopic dermatitis.
• Colon cancer risk. A 2019 study found that older adults supplementing high doses of vitamin B12 were at an increased risk of colon cancer.
• More hospital time and death. A 2016 study involving hospitalized people found that the participants with high B12 levels needed longer hospital stays and had a higher chance of dying. The participants included folks with cancer, liver disease, kidney diseases, and who were older adults and critically ill.
• Failed chemo treatment. A 2019 study involving people with breast cancer found less favorable chemotherapy outcomes for the participants taking B12 supplements.

Just note, we still need more research to know these outcomes are actually linked to B12 supplements. If anything, it’s a good reminder that you should def chat with your doc about finding out if you’re deficient in B12 before you take a supplement.

If you’ve got a more serious case of vitamin B12 deficiency, your doctor may recommend B12 shots to boost those B12 levels. These injections send a high dose of vitamin B12 straight into your system, helping to counteract the effects of a deficiency.

B12 injections are generally considered safe if you’re deficient, and side effects are super rare. Still, you may experience mild side effects like diarrhea and swelling. Call your doc if these symptoms don’t go away or get worse.

You can also encounter rare, serious side effects like:

• skin rash or hives
• weak muscles or cramps
• itching
• vomiting
• nausea
• headache
• leg pain or warm, tender pain in one leg
• dizziness and fatigue
• frequent peeing
• feeling super thirsty
• fast heart rate
• swelling of your extremities

It’s important to call your doc ASAP if you notice any of these negative effects.

Call 911 if you have an allergic reaction!

While also super duper rare, it is possible to have an allergic reaction to vitamin B12 injections.

If you have any symptoms of an allergic reaction (aka anaphylaxis), call 911 stat! These include:

• swollen face, tongue, and throat
• difficulty swallowing
• difficulty breathing

Was this helpful?

While B12 is fairly safe on its own, it doesn’t always play well with certain drugs or supplements. These meds can lower your body’s B12 levels by affecting absorption, so you might need to take a B12 supplement to keep those red blood cells in tip-top shape.

Common meds that B12 may interact with include:

• folic acid
• metformin
• vitamin C
• h3 blockers
• chloramphenicol
• proton pump inhibitors
• aminosalicylic acid
• colchicine
• gastric acid inhibitors

Talk with your doc before adding B12 to your diet if you’re currently taking any medications. To avoid any serious interactions, they may recommend specific dosage amounts or suggest taking medications and B12 supplements at different times.

B12 is a water-soluble vitamin that is absorbed in your intestines. That means any extra your body doesn’t need is flushed out of your system when you sweat or pee. (Science!)

Because of this, there’s actually no tolerable upper intake level (UL) for B12 (the max dose you can take before you experience side effects). But if you’re not deficient in B12, taking a B12 supplement is still linked to side effects.

On top of that, B12 is a unique water soluble vitamin because your body is great at storing it. An average person can have enough stored B12 to last them 3 to 5 years! That said, deficiency is rare and can only be confirmed through a lab test.

If you have any questions or concerns about what dose of B12 is best for you, talk with your doc for guidance.

First things first: If you start experiencing any side effects from taking B12 supplements, stop taking them ASAP.

Symptoms continuing to pester you or getting worse? Time to dial up your doc.

They can help figure out what’s going on (like if you’re taking doses that are too high or if another supplement is interfering with your B12 levels) and help you figure out the best course of action. This may include adjusting dosage amounts, adding more B12-rich foods to your diet, or simply skipping supplements altogether.

The National Institutes of Health shares the following recommended dietary allowances (RDAs) in micrograms (mcg) when it comes to vitamin B12:

• Teens and adults more than 14 years old: 2.4 mcg
• Pregnant women: 2.6 mcg
• Breastfeeding women: 2.8 mcg

Food is also a great source of nutritional goodness, and many people are able to fulfill all of their B12 needs through diet alone. You can get your RDA of this vital vitamin by eating B12-rich foods, like:

• red meat
• lamb
• chicken or turkey
• fish
• shellfish
• milk
• eggs
• liver
• cheese

We know, we know: Many of these foods aren’t fit for the awesome vegans and vegetarians among us. For our more plant-based friends, there are a variety of fortified foods that can give you that B12 boost, such as certain soy products, foods containing yeast extracts, and even many bread and cereals (yums!).

Vitamin B12 is necessary for your body’s overall wellness needs. You can get most of your B12 intake from common foods, like meat, dairy, fish, or fortified foods like bread or cereal.

But if you need an extra B12 boost thanks to a deficiency, supplements or injections may help. If you aren’t deficient, you may experience side effects taking a supplement.

While rare, you may also experience not-so-fun side effects, or even a life threatening allergic reaction, from a B12 injection.

If you experience any adverse effects from your B12 supplement, stop taking it. Symptoms should go away on their own. If they don’t subside or they get worse, talk with your doc. They can see what’s up and recommend treatment.

B12 Side Effects and Interactions

Like all good things, too much of any vitamin or mineral can stir up trouble. Vitamin B12 is no exception and can cause side effects.

Vitamin B12 is essential for DNA production, red blood cell formation, DNA synthesis, and brain health. But if you take B12 supplements, you risk ingesting more B12 than you actually need. Here are the deets.

B12 supplements come in a variety of forms, including capsules, tablets, soft gels, gummies, and drops or sprays.

Taking these B12 supplements when you aren’t deficient may cause side effects like:

• nausea
• vomiting
• headache
• diarrhea
• tiredness
• feeling weak
• tingling or numbness in your extremities

If you notice any of these side effects, stop taking B12. And call your doc if anything gets worse.

While not fully proven side effects, research has also linked the following health risks to taking high dose B12 supplements when you aren’t deficient, like:

• Skin conditions. A 2015 research review linked taking too much B12 to acne, rosacea, vitiligo, and atopic dermatitis.
• Colon cancer risk. A 2019 study found that older adults supplementing high doses of vitamin B12 were at an increased risk of colon cancer.
• More hospital time and death. A 2016 study involving hospitalized people found that the participants with high B12 levels needed longer hospital stays and had a higher chance of dying. The participants included folks with cancer, liver disease, kidney diseases, and who were older adults and critically ill.
• Failed chemo treatment. A 2019 study involving people with breast cancer found less favorable chemotherapy outcomes for the participants taking B12 supplements.

Just note, we still need more research to know these outcomes are actually linked to B12 supplements. If anything, it’s a good reminder that you should def chat with your doc about finding out if you’re deficient in B12 before you take a supplement.

If you’ve got a more serious case of vitamin B12 deficiency, your doctor may recommend B12 shots to boost those B12 levels. These injections send a high dose of vitamin B12 straight into your system, helping to counteract the effects of a deficiency.

B12 injections are generally considered safe if you’re deficient, and side effects are super rare. Still, you may experience mild side effects like diarrhea and swelling. Call your doc if these symptoms don’t go away or get worse.

You can also encounter rare, serious side effects like:

• skin rash or hives
• weak muscles or cramps
• itching
• vomiting
• nausea
• headache
• leg pain or warm, tender pain in one leg
• dizziness and fatigue
• frequent peeing
• feeling super thirsty
• fast heart rate
• swelling of your extremities

It’s important to call your doc ASAP if you notice any of these negative effects.

Call 911 if you have an allergic reaction!

While also super duper rare, it is possible to have an allergic reaction to vitamin B12 injections.

If you have any symptoms of an allergic reaction (aka anaphylaxis), call 911 stat! These include:

• swollen face, tongue, and throat
• difficulty swallowing
• difficulty breathing

Was this helpful?

While B12 is fairly safe on its own, it doesn’t always play well with certain drugs or supplements. These meds can lower your body’s B12 levels by affecting absorption, so you might need to take a B12 supplement to keep those red blood cells in tip-top shape.

Common meds that B12 may interact with include:

• folic acid
• metformin
• vitamin C
• h3 blockers
• chloramphenicol
• proton pump inhibitors
• aminosalicylic acid
• colchicine
• gastric acid inhibitors

Talk with your doc before adding B12 to your diet if you’re currently taking any medications. To avoid any serious interactions, they may recommend specific dosage amounts or suggest taking medications and B12 supplements at different times.

B12 is a water-soluble vitamin that is absorbed in your intestines. That means any extra your body doesn’t need is flushed out of your system when you sweat or pee. (Science!)

Because of this, there’s actually no tolerable upper intake level (UL) for B12 (the max dose you can take before you experience side effects). But if you’re not deficient in B12, taking a B12 supplement is still linked to side effects.

On top of that, B12 is a unique water soluble vitamin because your body is great at storing it. An average person can have enough stored B12 to last them 3 to 5 years! That said, deficiency is rare and can only be confirmed through a lab test.

If you have any questions or concerns about what dose of B12 is best for you, talk with your doc for guidance.

First things first: If you start experiencing any side effects from taking B12 supplements, stop taking them ASAP.

Symptoms continuing to pester you or getting worse? Time to dial up your doc.

They can help figure out what’s going on (like if you’re taking doses that are too high or if another supplement is interfering with your B12 levels) and help you figure out the best course of action. This may include adjusting dosage amounts, adding more B12-rich foods to your diet, or simply skipping supplements altogether.

The National Institutes of Health shares the following recommended dietary allowances (RDAs) in micrograms (mcg) when it comes to vitamin B12:

• Teens and adults more than 14 years old: 2.4 mcg
• Pregnant women: 2.6 mcg
• Breastfeeding women: 2.8 mcg

Food is also a great source of nutritional goodness, and many people are able to fulfill all of their B12 needs through diet alone. You can get your RDA of this vital vitamin by eating B12-rich foods, like:

• red meat
• lamb
• chicken or turkey
• fish
• shellfish
• milk
• eggs
• liver
• cheese

We know, we know: Many of these foods aren’t fit for the awesome vegans and vegetarians among us. For our more plant-based friends, there are a variety of fortified foods that can give you that B12 boost, such as certain soy products, foods containing yeast extracts, and even many bread and cereals (yums!).

Vitamin B12 is necessary for your body’s overall wellness needs. You can get most of your B12 intake from common foods, like meat, dairy, fish, or fortified foods like bread or cereal.

But if you need an extra B12 boost thanks to a deficiency, supplements or injections may help. If you aren’t deficient, you may experience side effects taking a supplement.

While rare, you may also experience not-so-fun side effects, or even a life threatening allergic reaction, from a B12 injection.

If you experience any adverse effects from your B12 supplement, stop taking it. Symptoms should go away on their own. If they don’t subside or they get worse, talk with your doc. They can see what’s up and recommend treatment.

Vitamin B12 – why the body, higher or lower, what to do

Why the body needs vitamin B12

Vitamin B12 (vitamin B12, vitamin B12) is a whole group of biologically active substances containing cobalt (cobalamins). It includes cyanocobalamin, hydroxocobalamin, methylcobalamin and cobamamide.

But more often, when talking about vitamin B12, they mean only cyanocobalamin: it is in this form that most of the vitamin enters the body.

Vitamin B12 helps the body provide important processes:

• DNA synthesis,
• energy production,
• maintenance of the normal function of the nervous system.

Also, vitamin B12, along with other B vitamins, is involved in the folate cycle – the process of converting the amino acid homocysteine ​​into methionine. If vitamin B12 is not enough, this process can be disrupted. At the same time, homocysteine ​​begins to accumulate in the body. It damages the inner walls of blood vessels, and cholesterol plaques are more easily deposited on them (atherosclerosis develops) and blood clots are formed – blood clots. This often leads to blockage of the veins, followed by a heart attack or stroke.

An increase in homocysteine ​​levels can also be dangerous for pregnant women: the risk of developing severe complications (miscarriage, preeclampsia and eclampsia, venous thrombosis, pulmonary embolism, fetal malformations) increases.

In addition, vitamin B12 helps prevent the development of anemia – a decrease in the number of red blood cells in the blood.

Anti-anemic factors, that is, substances that stimulate hematopoiesis, were discovered in 1930 by the American physiologist and hematologist William Bosworth Castle. He discovered that certain cells in the stomach produce a special protein that forms a complex with vitamin B12, which allows the vitamin to be absorbed. The protein discovered by Castle was called the intrinsic factor of Castle, and vitamin B12 was called the extrinsic factor of Castle.

Vitamin B12 deficiency disrupts the division and maturation of red blood cells – erythrocytes – in the bone marrow. Their number in the blood decreases, and the volume increases. Because of this, tissues experience oxygen starvation.

B12 deficiency anemia is one of the most common anemias, especially in the elderly, vegetarians and vegans, people who abuse alcohol. Another reason why B12 deficiency anemia can develop is autoimmune gastritis. In this disease, the internal factor of Castle is either produced in insufficient quantities or not produced at all due to the body’s autoimmune reaction to this protein or to the stomach cells themselves that synthesize it. As a result, the external factor of Castle, that is, vitamin B12, is not absorbed – and the process of hematopoiesis is disrupted.

Vegetarianism often contributes to the development of B12 deficiency anemia

Why get tested for vitamin B12

The doctor may recommend taking a blood test for vitamin B12 to find out the cause of anemia or neuropathy (impaired impulse conduction along the nerve fiber), as well as to monitor the effectiveness of their treatment.

Vitamin B12

The study determines the content of vitamin B12 in the blood and allows you to identify its deficiency, understand the cause of anemia and neuropathy or monitor the effectiveness of their treatment. It is recommended to take in combination with other laboratory tests for vitamins of group B.

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In addition, the study may be prescribed for pregnant women, as well as nursing mothers.

Common indications for testing :

• symptoms of vitamin B12 deficiency;
• detection of macrocytes (enlarged erythrocytes) based on the results of a general blood test;
• hyperhomocysteinemia – increased level of homocysteine ​​in the blood;
• age of the patient: in children and the elderly, vitamin B12 may be poorly absorbed;
• malnutrition: vegan or vegetarian diet;
• alcohol abuse;
• taking vitamin B12 supplements.

A doctor of any specialization can refer a patient for analysis.

How to prepare for a vitamin B12 test

In order for the result of a blood test for vitamin B12 to be correct, it is enough to follow simple recommendations.

• Donate blood on an empty stomach, between 8 am and 11 am. During the day, blood counts can change significantly, the result of the morning analysis is the most reliable.
• 24 hours before the test, alcohol should be excluded and intense physical activity should be avoided.
• Do not eat or drink juice, milk or other beverages 8 hours before blood sampling. You can drink non-carbonated water. On the eve of the study, it is better to have a light, low-fat meal for dinner.
• 1-2 hours before the analysis, it is advisable not to smoke, avoid stress and physical exertion (running, fast climbing stairs).
• 15 minutes before taking blood, it is advisable to have a little rest: sit in the laboratory department, catch your breath, calm down.

Rules for taking blood from children :

• infants up to 1 year
• children under 7 years old

To monitor indicators in dynamics, you should take an analysis under the same conditions: in the same laboratory, at the same time of day. Women should take into account the phase of the menstrual cycle.

What can affect the result of the study

Medications and medical procedures may affect test results.

Do not donate blood immediately after physiotherapy, instrumental examination, X-ray or ultrasound examination, massage.

It is best to perform a blood test before starting medications or 10-14 days after they are discontinued. The nurse should be warned about the medications taken, as well as the doctor who performs the diagnosis or prescribes the treatment.

How the study is carried out and when will the result be ready

For analysis, blood is taken from a vein located on the elbow bend of the arm.

The study is carried out by the method of immunochemiluminescent analysis. The result of the test will be presented in a quantitative format: the concentration of vitamin B12 is given on the form in picograms per milliliter.

The analysis will be ready in 1 day if submitted on time: the abbreviated schedule of appointments can be found on the page of the desired laboratory department. If you take the test outside of the schedule, the test completion time may be extended by 1-3 days.

What does a vitamin B12 test result mean

Only a doctor should interpret the result of the study based on all the data he has.

A blood level of vitamin B12 less than 140 pg/mL is considered low.

What is the norm for men

The norm of vitamin B12 for men depends on age:

• birth to 2 years: 293–1210 pg/mL;
• 2–3 years: 264–1220 pg/mL;
• 4–6 years: 245–1080 pg/mL;
• 7–9 years: 271–1170 pg/mL;
• 10–12 years: 183–1090 pg/mL;
• 13–16 years: 214–865 pg/mL;
• 17 years and older: 191-663 pg/mL.

What is the norm for women

The norm of vitamin B12 for women, as well as for men, depends on age:

• Birth to 2 years: 228-1510 pg/mL;
• 2–3 years: 416–1210 pg/mL;
• 4–6 years: 313–1410 pg/mL;
• 7–9 years: 247–1170 pg/mL;
• 10–12 years: 197–1020 pg/mL;
• 13–16 years: 182–878 pg/mL;
• 17 years and older: 191-663 pg/mL.

What low vitamin B12 values ​​indicate

Vitamin B12 deficiency is dangerous: it can lead to the development of anemia. Also, due to a lack of a vitamin, homocysteine ​​​​levels can increase. This significantly increases the risk of developing cardiovascular diseases, and in pregnant women – severe pathologies.

Symptoms suggestive of vitamin B12 deficiency :

• fatigue,
• palpitations,
• lethargy,
• shortness of breath,
• headache,
• pallor,
• loss of appetite,
• visual impairment,
• problems with memory and concentration,
• irritability,
• inflammation of the tongue,
• Numbness of hands and feet.

Sudden loss of vision may indicate vitamin B12 deficiency

Main causes of vitamin B12 deficiency :

• Malabsorption. This occurs with resection of the stomach, inflammatory diseases of the stomach and intestines, diseases of the pancreas, lack or absence of the internal factor of Castle, as well as alcohol abuse.
• Unbalanced diet. Vitamin B12 deficiency can develop in people who follow a vegetarian or vegan diet because this vitamin is found predominantly in animal products.
• Alcohol abuse.
• Long-term use of certain drugs. Oral contraceptives, colchicine, metformin, vitamin C supplements, aminosalicylic acid, omeprazole, some antibiotics interfere with the absorption of vitamin B12.
• Worm infestation. Worms in the intestines “take away” vitamin B12 from food, which can lead to its deficiency. For this reason, vitamin deficiency can develop in children.

What high vitamin B12 values ​​indicate

Normally, vitamin B12 does not accumulate in the body (its excess is excreted in the urine). If, according to the results of the analysis, an increase in its level is observed, then this is usually a consequence of the uncontrolled use of vitamin supplements.

Other possible causes of vitamin B12 excess are blood diseases (leukemia, polycythemia) or liver disease (hepatitis, cirrhosis), diabetes, AIDS.

At the same time, an increase in the content of vitamin B12 in the blood, as a rule, does not lead to complications.

Symptoms of vitamin B12 excess :

• headache;
• abdominal pain;
• dizziness, confusion;
• nausea;
• diarrhea;
• weakness.

What additional examinations are prescribed in case of deviation from the norm

If your blood levels of vitamin B12 are abnormal, your doctor may recommend checking other levels.

So, for the diagnosis of anemia, they can prescribe a general blood test with a study of the level of erythrocytes and reticulocytes in the blood and the determination of the average content and average concentration of hemoglobin in erythrocytes, the size of erythrocytes.

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And in order to distinguish between B12-deficiency and folic acid deficiency anemia, it may be recommended to take a test for the level of folates – derivatives of folic acid – in the blood.

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Since the cause of vitamin B12 deficiency can be helminthic invasion, it is advisable to pass special tests.

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A stool test may be ordered to check for intestinal dysbiosis, which may also interfere with normal absorption of vitamin B12.

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It is also useful to assess the condition of the liver and kidneys.

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How to maintain normal vitamin B12 levels

To maintain normal levels of vitamin B12, most people simply need to eat a nutritious and varied diet.

Thus, one egg contains approximately 0.6 mcg of vitamin B12, a serving of beef (85 g) – 1.4 mcg, and a serving of tuna (85 g) – 2.5 mcg. At the same time, the daily physiological need for vitamin B12 in adults is 3 mcg, in children – 1.4–3 mcg.

At the same time, older people produce less gastric juice and intrinsic factor Castle (a protein synthesized by stomach cells), which makes it difficult to absorb vitamin B12. Its deficiency is detected in every 50th person over 60 years old and in every 15th person over 70 years old. Therefore, older people are advised to take additional vitamin B12 – with dietary supplements and fortified foods.

The same recommendations are relevant for pregnant and lactating women: their need for the vitamin increases.

What foods contain vitamin B12: meat, organ meats, seafood and fish, dairy products and eggs

It is also important to properly prepare foods containing vitamin B12. Since it is water-soluble, it is washed out during cooking. To get the maximum amount of vitamin B12 from your food, it is best to fry or steam or grill it.

Sources

1. Vitamin B12 deficiency anemia: clinical guidelines / Ministry of Health of the Russian Federation. 2021.

Vitamin B12 deficiency symptoms

Vitamin B12 is an essential nutrient your body needs for processes such as DNA synthesis, energy production, and brain and central nervous system function. It plays an important role in the formation of red blood cells. It plays an important role in the metabolism of every cell in the body, as well as in DNA synthesis. Vitamin B12 deficiency can cause anemia, fatigue, nerve damage, and other problems.

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Causes of vitamin B12 deficiency

• malabsorption

  Malabsorption of vitamin B12 can be caused by many causes, such as anemia in autoimmune gastritis , surgical removal of the stomach, chronic inflammation of the pancreas, intestinal parasites, genetic disorders and certain medications.

  Because the ability to absorb B12 from food decreases with age, deficiency is more common in older people. However, B12 deficiency can also occur in children and young adults.

• Inadequate diet

  Vitamin B12 deficiency can be caused by malnutrition or improper diet, such as a vegetarian diet.

Vitamin B12 deficiency symptoms

Vitamin B12 is an essential nutrient needed for the proper functioning of the brain and nervous system, and for the formation of red blood cells. Vitamin B12 deficiency can cause a variety of symptoms.

Let’s look at the 5 main symptoms of vitamin B12 deficiency.

• Fatigue and weakness

  Vitamin B12 is essential for the production of red blood cells, which are responsible for carrying oxygen from the lungs to the tissues of the body. When the body is deficient in vitamin B12, it can lead to a decrease in the number of red blood cells, leading to a condition called anemia.

  Anemia can cause a range of symptoms including fatigue, weakness, shortness of breath and dizziness. Oxygen is necessary for the production of energy in the body, and without it, the cells and tissues of the body cannot function normally. Shortness of breath occurs due to the fact that the body does not receive enough oxygen due to a decrease in the number of red blood cells. Dizziness can also occur due to a lack of oxygen in the brain.

  Vitamin B12 is involved in the metabolism of carbohydrates, fats and proteins, which are the main sources of energy in the body. Without enough vitamin B12, the body’s ability to produce energy from these nutrients is reduced, leading to fatigue and weakness.

• Neurological problems

  Studies have shown that vitamin B12 deficiency can cause changes in the structure and function of the brain, which can lead to cognitive decline and memory loss. Vitamin B12 plays an important role in the production of myelin, a fatty substance that forms a protective sheath around nerve fibers in the brain. Without enough vitamin B12, the myelin sheath can be damaged, causing problems with nerve impulse transmission and cognitive function.

  Vitamin B12 plays a role in the synthesis of neurotransmitters such as serotonin and dopamine, which are important for mood, memory and cognition. Without enough vitamin B12, the production of these neurotransmitters can be disrupted, which can lead to cognitive decline and memory loss.

  Nerve damage caused by vitamin B12 deficiency can cause numbness or tingling in the hands and feet. Vitamin B12 deficiency can cause difficulty walking and balance problems.

• Mouth and tongue problems

  Vitamin B12 is essential for the proper functioning of the cells in the mouth and digestive system. When the body is deficient in vitamin B12, it can lead to a condition called glossitis, which is an inflammation of the tongue. Glossitis causes swelling, redness, and soreness of the tongue, making it difficult and painful to eat or speak.

  Vitamin B12 deficiency can also lead to cold sores, which are small, painful sores that develop in the mouth. These sores can occur on the tongue, lips, gums, or inside of the cheeks. Vitamin B12 deficiency can weaken the immune system, making it easier for bacteria to infect the mouth and cause ulcers.

• Digestive problems

  Vitamin B12 plays an important role in the proper functioning of the digestive system, including the absorption of nutrients and the regulation of bowel movements. When the body is deficient in vitamin B12, it can lead to a change in bowel habits. Studies have shown that vitamin B12 deficiency can lead to gastrointestinal symptoms such as constipation, diarrhea, bloating, and loss of appetite. These symptoms may be related to disruption of the normal digestive processes, which can affect the movement of food through the intestines.

  Vitamin B12 deficiency can lead to a condition called bacterial overgrowth in the small intestine. It occurs when there is an overgrowth of bacteria in the small intestine, which can lead to gastrointestinal symptoms such as diarrhea, bloating, and abdominal pain.

• Vision problems

  Vitamin B12 is important for the proper functioning of the nervous system, including the nerves that control vision. When the body is deficient in vitamin B12, it can cause neurological symptoms, including vision problems. Research has shown that vitamin B12 deficiency can cause changes in the optic nerve, which is responsible for transmitting visual information from the eyes to the brain. This can lead to vision problems such as blurred vision, double vision or blurred vision.

Summary

Vitamin B12 supplements can interact with certain medications, such as metformin used for diabetes, proton pump inhibitors used for acid reflux, and some antibiotics. Taking more than the recommended dose of vitamin B12 can cause side effects such as acne, diarrhea, and upset stomach.