Vitamins

My wife is pregnant and taking her prenatal vitamins. Obviously folate is the most important one, its role in preventing neural tube defects is well-documented. Today during breakfast she said I could be taking some too as a supplement to my diet, so should I?

Probably not. No good data, that I am aware of, showing benefit of taking vitamin supplements exist. Actually all studies I could recall showed no benefit or potentially harm. That's what I told my wife. What I also knew for sure, is that our morning conversation took place in the wake of a recent publication by Mursu and colleagues of a large observational study showing increased mortality rate in older women taking dietary supplements. 

However, I thought I'll spend some more time today googling and pubmeding.

Let's start with the USPSTF. In the 2003 recommendation the USPSTF stated there is insufficient data to recommend for or against the use of supplements with vitamin A, C, or E, multivitamin with folic acid, or antioxidant combinations for cardiovascular disease and cancer prevention. They recommend against the use of beta-carotene.

Publication by Mursu et al. I mentioned above is not the first report showing potential risks of taking supplements. In 2007 a review of randomized trials published in JAMA showed a possible increase in mortality with vitamin A and beta-carotene. Not with selenium or vitamin C however. Beta-carotene was also associated with higher rate of lung, prostate an stomach cancer in the ATBC Cancer Prevention Study. 

Another study looking at antioxidant role in CAD when given alone or combined with simvastatin and niacin (HATS study) showed antioxidants attenuate the beneficial effect of these medications on LDL and HDL levels and on clinical end-points. Also a recent Cochrane review showed no benefit of antioxidant supplements in primary or secondary prevention in various diseases.

Seems I will not take the vitamins after all, but even more I will not recommend them to my patients and warn them of potential harms if they are already taking them.