Dietary fibre intake helps prevent total, cause-specific deaths
Consumption of fibre-rich foods may reduce all-cause and cause-specific mortality, such as cardiovascular disease (CVD)-, respiratory- and injury-related deaths, in both men and women, a large prospective study in Japan has shown. Cancer mortality, however, is reduced only in men.
“Since high fibre intake from fruits, vegetables and bean was associated with lower total mortality, increasing fibre intake from these sources may be an option for achieving an adequate fibre intake according to dietary guidelines,” the researchers said.
This large-scale population-based cohort study included 92,924 participants (aged 45–74 years; 50,170 women) who completed a validated questionnaire with 138 food items. The researchers calculated dietary fibre intake, which they divided into quintiles.
A total of 19,400 deaths were recorded during a mean follow-up of 16.8 years. Multivariable-adjusted models revealed that total, soluble and insoluble fibre intakes were inversely correlated with all-cause mortality. [Am J Clin Nutr 2020;111:1027-1035]
Total mortality in the highest quintile of total fibre intake compared with the lowest quintile was significantly reduced in men (hazard ratio [HR], 0.77, 95 percent confidence interval [CI], 0.72–0.82; ptrend<0.0001) and in women (HR, 0.82, 95 percent CI, 0.76–0.89; ptrend<0.001).
Higher quintiles of dietary fibre intake also significantly correlated with lower mortality due to total CVD, respiratory disease and injury in both men and women. On the other hand, dietary fibre intake was inversely associated with cancer mortality in men but not in women.
“This finding is consistent with that of a prospective study of cancer mortality conducted in the US, whereas total fibre intake was significantly associated with cancer mortality in both sexes in a study conducted in Europe,” the researchers said. [Am J Clin Nutr 2012;96:164-174; Arch Intern Med 2011;171:1061-1068]
“These sex-based differences might have been caused by differences in dominant cancer sites, in relation to cancer deaths, between men and women,” they added.
In addition, intake of fibre from fruits, beans and vegetables, but not from cereals, reduced total mortality. An inverse association was also observed between dietary fibre intake and several noncommunicable diseases, but evidence of this effect remains unclear in the Asian population.
This benefit could be explained by several mechanisms. For instance, fibre has been shown to have cholesterol-lowering, blood pressure-lowering, insulin-sensitizing and anti-inflammatory effects. [Am J Clin Nutr 1999;69:30-42; Nutr Rev 2009;67:188-205; Arch Intern Med 2005;165:150-156; Am J Clin Nutr 1990;52:524-528; Nutrition 2008;24:941-949]
In Japan, the recommended amount of fibre is 20 and 28 g/d in men and women, respectively. However, the mean fibre intake of this population is below the recommended levels. [www.mhlw.go.jp/file/06-Seisakujouhou-10900000-Kenkoukyoku/0000208960.pdf; www.mhlw.go.jp/content/000451759.pdf]
“Our study showed that, in addition to fruits and vegetables, dietary fibre from soybeans was inversely associated with total mortality,” the researchers said. “Therefore, increasing soybean, as well as vegetable and fruit, consumption may be a strategy to increase dietary fibre intake in Japan.”