How many people do you know who are not taking their daily multivitamin pill? Not many, I’d bet. Heck, even I, a just-the-facts-ma’am kind of guy, succumbed to the general belief that supplements at worst provide insurance against deficiencies; at best they may protect us from a whole raft of diseases, from the flu to arthritis and even Alzheimer’s, and thus make us healthier, help us live longer, be happier, perform better in our favorite sport, become sexual athletes –and this is only a partial list of the promised miracles. Except that the age of miracles has long passed, and none of the promises have been borne out.

What are vitamins?

Let’s think about it rationally. Vitamins are chemical compounds that are needed for normal metabolism and are not synthesized by the body, but
obtained from our diet. They perform specific functions. For instance, Vitamin C is needed for the proper synthesis of collagen (specifically, formation of cross links between collagen molecules to form the dermis, tendons and ligaments that hold us together). The gotcha squad –hold the emails; I did not forget the antioxidant property of vitamin C. Except that to date no convincing study has shown that it does anything for us in terms of health and the pursuit of happiness. The antioxidant property is a consequence of the molecular structure needed to perform its collagen cross-linking function, not to protect us from those free radicals which threaten to kill us all (I am referring here to oxygen free radicals, not the Wall Street occupiers kind).

Let’s take it a step further.

Shouldn’t we have Vitamin C for the Proven functions it performs? The answer is yes, but the amounts that are needed are so minuscule that we get it in our daily diet, regardless how badly we eat. To get an idea of how tiny these amounts are just consider that our dietary requirements of proteins, carbohydrates and fats are measured in hundreds of grams per day. Drugs are measured in terms of milligrams per day. Vitamins are measured in micrograms per day –that is one millionth of a gram! We need such tiny amounts because vitamins function biochemically as cofactors, meaning that they participate in the chemical reaction that a specific enzyme performs, and once done –they move on to the next  enzyme molecule that performs that function. In other words –nature is designed to recycle the cofactors (vitamins) so as to minimize our dependence on exogenous factors that are beyond our control and may fluctuate wildly. We don’t have to go all the way back to our hunter-gatherer ancestors to understand the vicissitudes of nature; the famine in Somalia is a stark example.

I dwelled on vitamin C as an example only. We could repeat the same story for every single vitamin. Folic acid and vitamin B12 are cofactors for enzymes involved in DNA synthesis, vitamin B6 is a cofactor in amino acids synthesis, and so on. I can already see what’s going on in your mind; “yea, I know, it doesn’t make scientific sense. But every other day they come up with conflicting claims and scare stories. I might as well hedge my bets and take the pill as insurance”. I must admit, I take my morning multivitamin pill with the same unspoken argument in my head. If this is all we do, no harm done as far as we know; the excess of the water-soluble vitamins (A, B complex, C) literally go down the drain –in the urine. The lipid-soluble (D, E, K) are stored in fat tissue and eventually find their way into the bile, and down the drain –in the stool.

Too much of a good thing is not harmless

The problem starts with the humongous amounts of supplements that people take. Excess vitamin D can cause thickening of the skull in newborns whose mothers took vitamin D supplements.  In a study published in the October issue of the Archives of Internal Medicine, 38,000 older women (mean age 61.6) were followed for 19 years. Those who took multivitamins, minerals and other supplements had a higher risk of dying compared to those who did not. The authors concluded that “In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron. In contrast to the  findings of many studies, calcium is associated with decreased risk.”

The 11 October, 2011 issue of JAMA (Journal of the American Medical Association) published the results of a study on prevention of prostate cancer with the antioxidants Vitamin E and selenium. An initial evaluation in early 2008 showed no effect. But an evaluation after a longer period of observation showed that there was a statistically significant increase of 17% in the risk of prostate cancer among 35,000 men who took the supplements. The amount of selenium they took was 200 micrograms (multivitamin pills contain 50 micrograms) and 400 International Units of  vitamin  E (multivitamin pills contain 50-200 I.U.).

This brings up another issue: is there a relationship between the dose taken and the degree of risk? Could a lower dose engender risk, albeit of a lower magnitude? What is a safe dose? The answers to such questions are still unknown. Of course there are situations where supplementation is beneficial. Folic acid taken by pregnant women reduces the risk of spina bifida in newborns. Bleeding can cause iron deficiency anemia and may require iron supplementation. Liver disease can cause vitamin K deficiency and dysfunction of the coagulation system. Older people, especially women, require calcium and vitamin D supplements to avoid osteoporosis and its complications. All those, and other examples require careful evaluation by a physician.

As these and other studies showed -more is not better. And hedging your bets, it turns out, is not as harmless as we thought.


Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Similar to what Jim heard, my Gastroenterologist has me on calcium for one thing and my Primary Care Doc has me on it for another, in addition to multi-vitamins. Plus my eye doctor has me on fish oil, which he says has kept my eyes healthy. so, are they wrong?

  2. Dov,
    I attended a workshop three years ago given by Mark Hyman MD, who corroborates with Andrew Weil. Mark runs a wellness clinic on the East Coast. The workshop was on health and nutrition. He recommended taking a high quality multi-vitamin and mineral tablet daily for insurance. Also he recommended 500 mg of calcium for bone strength and 1000 mg of omega 3 fatty acids for the brain. He wasn’t selling anything and wasn’t sponsored by any corporation.

  3. By “clean” I mean without an ulterior motive behind it, as Pharmaceuticals often do. Also, just because the Government is behind a study does not mean it is without bias.

  4. Juanito, you raise 2 questions: Is peer-review clean? If you mean by “clean” not corrupt -the answer is unequivocally yes. If you mean infallible-I’d be first to admit that there are many examples where deserving papers are rejected, and vice versa. The author is free to submit to another journal. If the paper is rejected by multiple journals, the science is probably not up to snuff. Regarding articles published in non-peer reviewed magazines: by and large they are either commercial propaganda or simply poor science. The 2 studies I cited were funded by NIH and NCI, no “smell” of drug companies.

  5. In your response to a person on this blog you make this statement:

    “The information you cite is from Mannatech -a supplement company, hardly an uninterested party. If you have references from peer-reviewed journal to substantiate your claims, I would like to read them.”

    But, are peer-reviewed articles that clean? Research takes a lot of money, which pharmaceuticals are eager to provide if it serves their purpose. And, most research starts out with a point of view, like, simplistically, supplements are not good for you. If the research results in proving their assumptions, they publish. if it doesn’t, we never hear about it. Plus, a lot of this research are on such small samples. I read one that said Disease Management doesn’t work, but their research covered 35 people. And for headline readers, they just think Disease Management doesn’t work!!!

    As with everything I think taking too much of anything is not good, as you point out with Vitamin D, but I smell Pharmaceuticals in this peer-reviewed report.

  6. Hello,

    The problem is nutritional losses in agricultural products due to modern agricultural practices of the past 60 years. Due to soil depletion the food is less nutritious.

    View this PDF posted on the mannatechscience website

    “Nutrient Levels in Fresh Fruits and Vegetables Are Declining”

    “Four recent studies reported that today’s fresh fruits and
    vegetables are lower in certain vitamins and minerals than
    they were as little as 50 years ago. These studies compared
    nutrient data from as early as 1930 to
    as recent as 19995, for the U.S., the
    U.K., and Canada. No matter the
    country nor the timeframe studied,
    the results are strikingly similar: the
    vitamin and mineral content of fruits
    and vegetables is decreasing. For
    example, two peaches would have
    supplied a woman’s vitamin A RDA
    in 1951. Today, she would have to
    eat almost 53 peaches to meet this
    requirement! ”

    If food was not losing its nutrition then supplaments would not be needed. However, that is not the case.

    Due to sun avoidance to skin cancer scares vitamin D is now deficient.

    Due to dairy fat content scares less calcium is consumed and there are deficienies in calcim too.

    Eat those 53 peaches of empty nutrition and see how that works out for you.

    People did not created this situation, we suffer under it.

    • “Average guy” describes some unbelievable losses of vitamin A in peaches. Since vitamin A is derived from the pigment in fruits, peaches in 1939 must have been 56 fold more colorful -not plausible on the face of it. Furthermore, fat-free milk has the same calcium content as whole milk. Calcium is in the form of water-soluble salts; not in the fat fraction.
      The information you cite is from Mannatech -a supplement company, hardly an uninterested party. If you have references from peer-reviewed journal to substantiate your claims, I would like to read them.

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