Beware of B-Vitamins: The Hidden Dangers of High Dose Supplements

The B-vitamins, including folic acid, vitamin B6, and vitamin B12, are essential for maintaining heart health. Good dietary sources include dark green leafy vegetables, whole grains, nuts, soy, fish, meat, poultry, and dairy products. We know that folic acid is essential for the development of the fetal nervous system, so in the US, and many other countries, commercially available grains are required to be fortified with folic acid. Thus, deficiencies of this vitamin are pretty rare. B12 deficiencies are sometimes seen in older folks, people with intestinal disease, alcoholics, and people on certain prescription medications. Vegans are often deficient in B12  (since animal and and dairy products are the only natural sources), so they usually need supplementation. B6 deficiencies are uncommon, except in alcoholics.

In the 1990's, there was a huge interest in high dose supplements, and megadoses of folic acid, B6, and B12 were often recommended by cardiologists. The idea was that by flooding the body with these supplements, we could decrease levels of homocysteine, a blood  marker that is associated with a higher risk for heart disease.

The problem with that theory was that it didn't work. Although we could lower homocysteine, we didn't lower risk at all. What we now know is that, in general, high homocysteine is a marker for an unhealthy lifestyle, and there is no vitamin pill that can fix that! Even more troubling was the fact that very high dose folic acid (over 400 mcg)  seemed to increase the risk that a stent placed in a heart artery would clog back up. So several years ago, most cardiologists backed off on recommending these supplements.

The research on folic acid supplementation also suggested something even more scary: an increase in cancer risk. Since the studies were not done to specifically look at that issue, no one could be sure if it was a real risk, or just a statistical fluke. Now a Norwegian study of several thousand patients, published in the Journal of the American Medical Association (Nov 18, 2010), gives us more compelling information. Norway does not have mandatory grain supplementation, making it a good place to study this issue. In this study, participants received 800 mcg of folic acid with B12 (400 mcg),  with or without B6 (40 mg). A separate group was given B6 alone. The study lasted a little over 3 years, and the participants were followed for another 3 years after stopping the supplements. 

The results? The risk of developing cancer (predominantly lung cancer) was 21% higher in those who took folic acid plus B12 . There was also an 18% higher likelihood of dying from any cause. B6, on the other hand, did not appear to have a major impact.

The bottom line? Get your folic acid from Mother Nature. Choose a Mediterranean diet, and you'll get plenty of all the nutrients you need to keep your heart healthy, lower your risk of cancer, and keep yourself looking and feeling great.