Prostate cancer mortality rates vary markedly throughout the world and migration data show that when men move from low-risk to high-risk countries, the offspring of these men acquire the risk of those in their adopted homeland. These data suggest lifestyle factors play a role in the etiology of prostate cancer. Among the various possible factors, much attention has focused on diet although the relationship between diet and prostate cancer risk remains unclear. New data suggest that dietary fiber may have a protective effect, but also that not all fibers are equal in this regard. French researchers evaluated the relationship between fiber intake and prostate cancer risk among 3313 men who were followed for a median period of 12.6 years. During that time, 139 men developed prostate cancer. Prostate cancer risk was inversely associated with total dietary fiber intake; when comparing men in the fourth versus first intake quartile, risk was reduced by 53% (P = 0.001). A similar benefit was associated with insoluble fiber and legume fiber. Independent of fiber, legume intake was also shown to be protective. In contrast, no associations between prostate cancer risk and intakes of soluble, cereal, vegetable and fruit fiber were reported. Although soy intake was not a focus of the current study, previous research indicates that soyfoods may reduce risk of developing prostate cancer by as much as 50 percent. Most evidence suggests it is the isoflavone content of soy that is responsible for protection against prostate cancer. However, this French study suggests that both the fiber provided by some soyfoods and the isoflavones may play a role in reducing prostate cancer risk.
Deschasaux M, Pouchieu C, His M, et al. Dietary total and insoluble fiber intakes are inversely associated with prostate cancer risk. J Nutr 2014.