This surprising result was reported recently in the Journal of Clinical Oncology, one of the most reputable and most read cancer journals. Click here for the abstract. Dr. Stark can send you the whole article (see box on the right). In this well-done study people were queried about their vitamin use, either in the form of single vitamins or multivitamins . The doses in the single vitamin pills were typically higher than what one would get by taking a one-a-day multivitamin, of which there are many on the market. What the scientists found was that when taken in high doses, vitamin B6 and vitamin B12 caused almost a doubling in the risk of lung cancer in men, but not women, especially among smokers, who were already at increased risk. Why this gender predominance, and why only these vitamins is totally unclear. The risk was only for pills, not for people who ate large amounts of vitamins through fruits and vegetables.
The issue of the value of vitamin supplements in health and disease has been controversial for a long time. Some years ago scientists discovered that various vitamin A and E derivatives were protective of lung cancer in China, where malnutrition is endemic, but not in the United States. Earlier lung cancer prevention trials using large doses of vitamins in the Western world showed the opposite, as did this study: an increased risk. The reasons for these results are mysterious but the implications are the same: don’t take large doses of B vitamins in an attempt to prevent cancer. You may be doing yourself more harm than good.