Dietary fiber and plant foods in relation to colorectal cancer mortality: The seven countries study

Many observational studies have found that higher consumption of vegetables , and to a lesser extent of fruits, was associated with lower risk of color ectal cancer, In particular, fiber or foods high in fiber have received att ention in the potential prevention of colorectal cancer. We performed an ec ological analysis with data of the Seven Countries Study, to investigate wh ether intake of fiber and plant foods contributes to cross-cultural differe nces in 25-year colorectal-cancer mortality in men. In the Seven Countries Study, around 1960 12,763 men aged 40 to 59 were enrolled in 16 cohorts in 7 countries. Baseline dietary information was gathered in small random samp les per cohort, and nutrient intakes were based on chemical analyses of the average diets per cohort. Crude and energy-adjusted mortality-rate ratios were calculated for a change of 10% of the mean intake of fiber and plant f oods, ie., total plant foods, fruits, vegetables, potatoes, grains, and rel ated sub-groups. Fiber intake was inversely associated with colorectal-canc er mortality with an energy-adjusted rate ratio of 0.89 (95% confidence int erval 0.80-0.97), An increase of 10 gram of daily intake of fiber was assoc iated with a 33% lower 25-year colorectal-cancer mortality risk. Intakes of vitamin B6 [0.84 (0.71-0.99)] and alpha-tocopherol [0.94 (0.89-0.99)] were also inversely associated with risk, Consumption of plant foods and relate d sub-groups was not related to colorectal cancer. It appears that fiber in take best indicates the part of plant food consumption, including whole gra ins, that is relevant for lowering colorectal cancer risk. Int. J. Cancer 8 1:174-179, 1999. (C) 1999 Wiley-Liss, Inc.