What is the history and controversy surrounding the use of intravenous high-dose vitamin C in cancer therapy? How does it work and what are the potential benefits and risks?

The Discovery and Early Uses of Vitamin C

The discovery and isolation of vitamin C was a pivotal advancement in improving human nutrition. Scurvy, a severe vitamin C deficiency disease characterized by weakness, lethargy, easy bruising and bleeding, was a major problem for sailors on long voyages during the 16th-18th centuries, when access to fresh fruits and vegetables was limited. It wasn’t until 1747 that Scottish naval physician James Lind demonstrated that consuming oranges and lemons could cure and prevent scurvy, which had been the leading cause of naval deaths at the time.

It took nearly two more centuries for scientists to identify the curative substance in citrus fruits as vitamin C. In 1932, Hungarian biochemist Albert Szent-Gyorgyi isolated and identified a 6-carbon carbohydrate, hexuronic acid, as the anti-scurvy factor, renaming it “ascorbic acid” in reference to its anti-scorbutic properties. He later received the Nobel Prize in Physiology and Medicine in 1937 for this discovery.

Vitamin C Deficiency and the Debate over Optimal Dosage

Today, vitamin C is a popular dietary supplement, and scurvy is rare due to improved access to fruits, vegetables, and vitamin supplements. However, a significant number of people, even in developed countries, still suffer from vitamin C deficiency. Approximately 7% of the US population has a plasma vitamin C concentration below the level considered scurvy.

Vitamin C has many essential functions in the body beyond its well-known role as an antioxidant. The optimal dosage required to maximize its health benefits has been a subject of debate since its discovery. Linus Pauling, a renowned chemist and two-time Nobel Prize laureate, strongly advocated for megadose quantities of vitamin C (above 1 g per day) to prevent and treat various illnesses, including the common cold and heart disease. However, mainstream medicine has largely ignored or even ridiculed Pauling’s claims, and this controversy continues today.

The Controversial History of High-Dose Vitamin C in Cancer Treatment

The use of high-dose vitamin C as a cancer therapy is also controversial. Nearly 60 years ago, Toronto physician William McCormick observed that cancer patients often presented with severely low levels of vitamin C in their blood and scurvy-like symptoms, leading him to hypothesize that vitamin C might protect against cancer by increasing collagen synthesis.

In 1972, Scottish surgeon Ewan Cameron extended this theory, proposing that ascorbate could suppress cancer development by inhibiting hyaluronidase, which otherwise weakens the extracellular matrix and enables cancer metastasis. Cameron began treating terminally ill cancer patients with high-dose vitamin C and published a case report of 50 patients, some of whom benefited from the treatment.

The Cameron-Pauling Trials and Ongoing Debate

Encouraged by the results, Cameron teamed up with Linus Pauling to conduct clinical trials involving terminal cancer patients. In 1976, they published a study of 100 patients with terminal cancer treated with ascorbate, comparing their disease progression and survival rates to 1000 retrospective control patients. Although the study had flaws, such as the lack of a placebo-control group, the results suggested that patients treated with vitamin C had improved quality of life and survival.

The Cameron-Pauling trials sparked a widespread debate within the medical community. Mainstream medicine largely dismissed the findings, citing the study’s limitations and the lack of placebo-controlled trials. However, proponents of high-dose vitamin C therapy argued that the results warranted further investigation and that the potential benefits outweighed the risks.

Proposed Mechanisms of Action for High-Dose Vitamin C in Cancer Therapy

The proposed mechanisms by which high-dose vitamin C may be effective in cancer therapy are multifaceted. Vitamin C is known to have antioxidant properties, which can help protect healthy cells from oxidative stress and potentially inhibit tumor growth. Additionally, high concentrations of vitamin C can generate reactive oxygen species, leading to selective toxicity against cancer cells.

Vitamin C may also enhance the effectiveness of certain chemotherapeutic agents and radiation therapy, potentially by improving the delivery of these treatments to the tumor site. Furthermore, vitamin C has been shown to modulate the immune system, which could contribute to its anti-cancer effects.

Current Research and Clinical Trials

Despite the ongoing controversy, researchers continue to investigate the potential benefits of high-dose vitamin C in cancer therapy. Several clinical trials are currently underway, exploring the use of intravenous vitamin C in combination with standard cancer treatments, as well as evaluating its effects on quality of life, symptom management, and survival outcomes.

The results of these trials will be crucial in determining the true efficacy and safety of high-dose vitamin C in cancer treatment. As the research continues, the medical community will need to weigh the potential benefits against the risks and limitations, ultimately reaching a consensus on the appropriate role, if any, of this controversial therapy.

Conclusion

The use of high-dose intravenous vitamin C in cancer therapy has a long and contentious history, marked by both promise and skepticism. While the proposed mechanisms suggest potential benefits, the overall evidence remains inconclusive, and the debate within the medical community persists. As research continues, the future of this controversial approach will depend on the outcome of well-designed, placebo-controlled clinical trials that can reliably evaluate its efficacy and safety.