Monday, February 25, 2008

The Upd and Downs of Vitamins

Should you take a daily multivitamin? This seems as obvious as motherhood and apple pie. Our understanding of the health benefits, and even health risks, of taking vitamins has advanced a lot in the past several years. The March, 2008 issue of the Harvard Men's Health Watch (HMHW) ( has an indepth review of the latest research on vitamin supplements.

There are 13 vitamins, chemicals that cannot be made by the body and are required for the body's metabolism. There are deficiency diseases for each one of them, like scurvy for a lack of Vitamin C. In order to function properly, our bodies need only small amounts of these vitamins, and a healthy balanced diet readily provides them. But, just in case, 35% of adults in the US take a multivitamin on a regular basis.

Vitamin intake rose dramatically in the 1980s and 1990s with evidence that anti-oxidants (Vitamin E, Vitamin C, Vitamin A and beta carotene which is converted to Vitamin A in the body) may help protect against heart disease and cancer. One report in 1999 showed that 39% of cardiologists were taking Vitamin E (not today, more on that later).

A second big boost to vitamin and other supplement intake came in 1994 when the Dietary Supplement and Health Education Act (DSHEA) was passed by Congress. Vitamins and other supplements were removed from the jurisdiction of the FDA and maufacturers could make great health claims without proof. After DSHEA, the sales of supplements in the US soared from $4 billion to over $21 billion dollars.

The early research on vitamins and supplements was observational, a crude type of research that does not prove cause and effect. Maybe vitamin takers were simply healthier people? Careful controlled research trials over the past 10 years have produced new light on taking vitamin supplements, light that shows very little benefit and even the risk of harm.

Careful research shows that taking anti-oxidant supplements do not protect against heart disease or cancer, and may increase the risk. For example, supplementation with Vitamin E may increase blood clotting and increase the risk of a heart attack or stroke. Almost all of those cardiologists have stopped taking Vitamin E. Beta carotene supplements increase the risk of lung cancer in male smokers, excess Vitamin A increases the risk of bone fractures and people who take anti-oxidant supplements may have a higher death rate per year than those who don't (HMHW, November 2007).

What about that great B vitamin, folic acid? We know that it prevents birth defects and lowers homocysteine, an amino acid associated with heart disease risk. Modest amounts of folic acid are helpful, but high amounts (1000 mcg or 1 mg or more) seem to make cancer tumors grow faster, raising the risk of more serious colon, prostate and breast cancer.

The HMHW states that there is one vitamin still standing that when taken as a supplement may provide more benefit than harm - Vitamin D. Vitamin D is important for bone health and taking supplements of 1000 IU or more may reduce cancer risk. Certainly more studies are needed.

Should you stop taking that one-a-day multiple vitamin? There is no evidence that the amounts in most once daily mutivitamins do any harm or good. However, if you take a heavy amount of vitamin supplements, you should take a careful look at current scientific evidence, and not the manufacturer's hype, and reconsider. A double tragedy is spending a lot of money and causing harm.

1 comment:

Robin Plan said...

Interesting post. I don't agree on several points. First Americans are not eating a healthy balanced diet. It's mostly processed food-like stuff with very little fruits and veggies, whole grains etc.Even our schools are feeding the kids processed food.

The harm from vitamins has been shown to be primarily from taking synthetic vitamins. A whole food multi does not cause the same health risk. It's made from "whole Food" not a sythetic created vitamin that a body cannot absorb. Ever wonder why Americans have the most expensive urine? Synthetic vitamins.
Read Are Vitamins Safe to learn and no there's no marketing hype involved.