Dietary fiber and plant foods in relation to colorectal cancer mortality: The Seven Countries Study

Abstract

Many observational studies have found that higher consumption of vegetables, and to a lesser extent of fruits, was associated with lower risk of colorectal cancer. In particular, fiber or foods high in fiber have received attention in the potential prevention of colorectal cancer. We performed an ecological analysis with data of the Seven Countries Study, to investigate whether intake of fiber and plant foods contributes to cross-cultural differences 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 samples 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 foods, i.e., total plant foods, fruits, vegetables, potatoes, grains, and related sub-groups.

Influence of micronutrients and related genes on colorectal cancer risk

“…Results from another large case-control study (1953 cases) in Italy also reported a significant reduction in risk of colorectal cancer associated with high dietary vitamin B6 intake (≥ 2.78 mg/d) [9]. In a between-country comparison designed to evaluate the role of plant foods in relation to colorectal cancer mortality [10], higher vitamin B6 intake was statistically significantly associated with lower mortality from colorectal cancer, after adjustment for energy and meat intake.…”

Diet and prevention of colorectal cancer

“…Caygill et al [2], in their ecologic analysis of FAO food consumption described under "Vegetables," above, found cereal consumption to be highly protective against colorectal cancer in both male and female subjects when the cereal is consumed at the present time; cereal levels consumed 20 years ago were also found to be protective for female subjects [2]. In contrast, investigators from the Seven Countries Study, based on analysis of meal composites from 16 cohorts, found no relation of grain consumption to colorectal cancer risk [17]. A recent US case-control study of colon cancer [5] showed an OR of 0.47 (0.25-0.91) for consumption of total cereals (cold and hot), and among men a similar OR was found for intake of breads and cereals (OR=0.43 [0.22-0.82]).…”

“…(average dietary fiber intake among US adults is 12-16 g/d). In the Seven Countries Study [17], fiber was highly related to colorectal cancer mortality. The mortality rate ratio for a 10% change in mean daily fiber intake was 0.89 (0.80-0.97), with an increase of 10 grams of fiber daily associated with 33% lower 25-year colorectal cancer mortality.…”

“…Among recent case-control studies, a large US multicenter study of colorectal cancer indicates that B6 is significantly protective as well, in the context of a protective effect for a variety of plant foods [17]. However, within the context of a randomized clinical trial of antioxidant vitamins to prevent polyp recurrence, only moderate evidence indicated that baseline dietary folate was protective against polyp recurrence; the protective effect was not seen after adjustment for dietary fiber and fat [46].…”

Strategies for prevention of colorectal cancer: Pharmaceutical and nutritional interventions

“…No association was observed between colorectal cancer and fruit and vegetable consumption for any frequency or type of food (RR, 1.08; 95% CI 0.84-1.38) for consumption of at least 6 servings of fruits and vegetables per day compared to 2 or fewer servings. An ecological analysis of data from the Seven Countries Study, which included groups from across Europe, the United States, and Japan, and represented 12,763 men aged 40 to 59 years old demonstrated no association of plant foods (fruits, vegetables, potatoes, and grains obtained from a one-week dietary history) and colorectal cancer incidence (P=0.183) [5]. [7].…”