One of the most impressive-sounding labels for an unproven alternative therapy is Orthomolecular Medicine. And the origin of the term, coined by Nobel laureate Linus Pauling, gives it added gravitas. As it turns out, though, it’s just a fancy way of claiming that there are medical benefits to giving high doses of vitamins above and beyond the ordinary, and quite small amounts necessary for normal health. Proponents of this concept argue that many diseases are due to undetected vitamin or mineral deficiencies, usually attributed to the unspecified evils of modern life or industrial agriculture. They also seem to follow the philosophy that if a little is good, more is better in arguing that extremely high doses of essential micronutrients can treat or prevent illness.
It is culturally difficult to argue against the benefits of vitamins, or to suggest they might cause harm. The memory of a time in which people in Western societies were routinely deficient in micronutrients, and when supplementation provided seemingly miraculous benefits, is still accessible. And there are still places in the world in which the poor not only do not have our nutrient-excess health problems but in which vitamin deficiencies are still common, and supplementation can be beneficial. Recent surveys suggest vitamins are seen as generally benign even by doctors, who commonly use them as placebo therapy.
However, the grand claims made in the 1970s by Pauling and others about the benefits of megadoses of vitamins have had a long time to prove themselves, and they have so far failed to do so. In human medicine, the loosely-organized set of theories called Orthomolecular Medicine has passed through the classic stages of CAM research:
1. An untested idea
2. An idea with support from a few random in vitro and animal model studies
3. An idea with a few supportive findings in small, poorly designed clinical studies
4. An idea clearly debunked in larger and better-designed studies but whose proponents cling to it tenaciously despite the lack of evidentiary support because they see themselves as visionaries ignored or oppressed by the unimaginative and venal mainstream medical establishment.
In veterinary medicine, as usual, not all of the stages are well-represented. The closest I have been able to find to Stage 3 are some case reports and papers from the 1970s that are long on grand theorizing and short on data by Dr. Wendell Belfield. These are balanced by a number of in vitro and animal model studies showing the implausibility or potential dangers megadoses of vitamins, but to my knowledge well-designed, adequately powered clinical trials have not been done to definitively prove or disprove any of the claims orthomolecular practitioners make. In my opinion, this is as it should be since the basic plausibility, the in vitro data, and the data from human medicine all argue against wasting resources on something so unlikely to prove safe and effective, but it is always nice to be able to show with solid data that likely nonsense truly is nonsense.
Since there do not appear to be definitive studies, I have put together some information of a cautionary nature about some commonly advocated vitamin therapies. This is certainly not a comprehensive literature review, nor do I claim it is the final word on megadose vitamin therapy. I have selected cautionary research to illustrate the potential risks of orthomolecular therapies and to remind everyone why the burden of proof is properly on proponents of this approach to justify their extravagant claims. It is also important to emphasize that the use of vitamins in high doses to prevent or treat disease is essentially using these compounds as drugs. They are not “nutritional” therapies when given above the recognized necessary amounts but active pharmaceuticals, and as such any possible benefits will come with associated risks and side effects.
As a fat-soluble vitamin, Vitamin A can accumulate over time, making reaching dangerous levels more likely. As for most vitamins, there are clear benefits to appropriate amounts, and supplementation sometimes shows benefit for people in impoverished environments with inadequate nutrition, but the evidence does not support benefits for supplementation of healthy people with adequate diets or clear benefits for treating non-deficiency diseases.
A Cochrane Review that presents mixed evidence for the possible benefit of Vitamin A for reducing mortality in children with measles. However, another review found no benefit for non-measles pneumonia.
A Chochrane Review showing Vitamin A does not reduce transmission of HIV from mother to offspring.
The original megavitamin Linus Pauling promoted obsessively in his later years. The most extensively studied claims of orthomolecular practitioners are those relating to Vitamin C, and these are the claims that have been most soundly disproven. In addition, recent evidence illustrates the real risks of large doses of Vitamin C.
Cochrane Reviews-Evidence does not support Vitamin C for prevention or treatment of the common cold and is generally absent or of unreliable quality for the use of Vitamin C in prevention or treatment of pneumonia, tetanus, and asthma.
There is a great deal of interest in the potential of this vitamin to reduce cancer risk. However, the evidence so far is mixed, with some studies showing a decreased risk (e.g. colon cancer), little or no change in risk (e.g. breast, prostate, and others), and even some increase in risk (e.g. pancreatic cancer among smokers). Excessive amounts can cause kidney stones, abnormal heart rhythms, and other serious side effects. This is one substance for which I think there is justification to conducting further research.
Multivitamins and Miscellaneous
A systematic review and meta-analysis published in the Lancet that suggests not only do antioxidants and Vitamin A and E supplements not prevent cancer, they may actually increase mortality risk.