The chemoprevention field could be characterized as being in a double-blind double bind. One side of the field emphasizes taking a "whole food" approach to using food to prevent cancer. That approach entails having scientists closely monitor everything a necessarily small group of subjects eats over a necessarily short period of time. Such studies pick apart the complexities of diet and its possible roles in keeping cancer at bay. But the small numbers and short time frame put any conclusions on statistically shaky ground.
The other side analyzes the effect of one thing at a time--usually a supplement or combination of supplements. Such approaches ignore the complexity of dietary interactions and consequently yield unexpected and perhaps incomplete results. One large trial that tested beta carotene as a potential chemopreventive found that it actually increased cancer rates in smokers; a then-unknown dietary mechanism actually changed the supplement's touted antioxidant activity into ...
