The study, which appears in the August issue of The Journal of Nutrition, followed 23,119 Japanese men and 35,611 women aged 40-79 years without a medical history of strokes or heart disease between 1988 and 1990.
All participants completed an initial 40-item food frequency questionnaire and had their soluble, insoluble and total dietary fiber and nutrient intake levels estimated. They were then grouped into five equal quartiles or groups depending on their estimated daily consumption of dietary fiber. The lowest-consuming first quartile ate a median of 6.8 g/d of total dietary fiber (TDF), while the highest fifth quarter consumed a median of 14 g/d.
During a 14-year follow-up period the relation between dietary fiber intake and CVD was documented, with 2,080 of total participants dying from CVD – 983 from strokes, 422 from coronary heart disease (CHD) and 675 from other CVDs.
The study found that men and women consuming the most fiber were 18 percent less likely to die from cardiovascular disease than those consuming the least during the course of the study. The results were more striking when in specific relation to CHD, with men and women who consumed the most fruit fiber 58 percent and 45 percent less likely to die. Similar trends were noted for cereal-derived but not vegetable fibers over the same period.
“Our results constitute supporting evidence that higher intake of both insoluble and soluble fiber, especially fruit and cereal fibers, may contribute to the prevention of coronary heart disease in Japanese men and women,” the authors wrote.
They pointed out that epidemiologic studies in the west suggest that dietary fiber intake offers protection against cardiovascular disease. Mean Japanese dietary fiber intake (around 14 g/d) is similar to that of some western countries, but until now like studies have been rare in Asia, making their study interesting in a comparative context.
Statistical adjustments were made to account for other variables, given that men and women in the fifth quartile with the highest TDF intake were more likely than the first quartile to have better general diets, be around six to nine years older, be better educated, take more exercise and less likely to drink alcohol and smoke.
Nonetheless, the authors did not rule out the possibility that these other factors may have influenced disease incidence: The apparent protective effect of fiber on risk of CHD may be due to other health-related habits, such as regular exercise, no smoking and a high fish intake by persons who consume greater amounts of dietary fiber.”
Moreover, they conceded that some participants may have changed their diets over the years following the questionnaire in such a way that results were affected: “Multiple evaluations of diet over time are important to reduce measurement errors.”
Source: The Journal of Nutrition (140:1445-1453, 2010)
“Dietary Fiber Intake is Associated with Reduced Risk of Mortality from Cardiovascular Disease among Japanese Men and Women.”
Authors: E-S. Ehab, I. Hiroyasu, D.Chigusa, K.Shogo, T.Akiko, W.Yoshiyuki, W.Yasuhiko, W.Kenji, JACC Study Group.