Anticancer Vitamins du Jour—The ABCED's So Far

"The only association observed in this set of 6 analyses was a troubling one: that risk of pancreatic cancer was doubled for those in the highest quintile of circulating vitamin D levels. This observation is disconcerting both because pancreatic cancer is now the fourth leading cause of cancer death in the United States and because the proponents of the vitamin D hypothesis are now arguing that substantially elevating circulating blood concentrations into that range should be a nutritional policy objective for the general population (15, 16). As pointed out by Dr. Helzlsouer (20) in this issue of the Journal, many ongoing randomized controlled trials are now using quite high doses of vitamin D. As we await clearer evidence of benefits from those trials, we will also need to be prepared to be vigilant about their individual and collective power to assess any potential harms (21, 22). It is timely for us to now reflect on the history of the past 25 years of our alphabetical approach to studying single vitamin deficiency states as causal factors for cancer. We have learned some hard lessons along the alphabetical way. We now know that supernutritional levels of vitamins taken as supplements do not emulate the apparent benefits of diets high in foods that contain those vitamins (13), and we now know that taking vitamins in supernutritional doses can cause serious harm. In short, we have found that the reality of human biology is far more complex than is suggested by our simple ideas."