HEALTH NEWS

Study Title:

Dietary fiber intake and risk of cardiovascular disease: systematic review and meta-analysis

Study Abstract

Objective To investigate dietary fibre intake and any potential dose-response association with coronary heart disease and cardiovascular disease.

Design Systematic review of available literature and dose-response meta-analysis of cohort studies using random effects models.

Data sources The Cochrane Library, Medline, Medline in-process, Embase, CAB Abstracts, ISI Web of Science, BIOSIS, and hand searching.

Eligibility criteria for studies Prospective studies reporting associations between fibre intake and coronary heart disease or cardiovascular disease, with a minimum follow-up of three years and published in English between 1 January 1990 and 6 August 2013.

Results 22 cohort study publications met inclusion criteria and reported total dietary fibre intake, fibre subtypes, or fibre from food sources and primary events of cardiovascular disease or coronary heart disease. Total dietary fibre intake was inversely associated with risk of cardiovascular disease (risk ratio 0.91 per 7 g/day (95% confidence intervals 0.88 to 0.94)) and coronary heart disease (0.91 (0.87 to 0.94)). There was evidence of some heterogeneity between pooled studies for cardiovascular disease (I2=45% (0% to 74%)) and coronary heart disease (I2=33% (0% to 66%)). Insoluble fibre and fibre from cereal and vegetable sources were inversely associated with risk of coronary heart disease and cardiovascular disease. Fruit fibre intake was inversely associated with risk of cardiovascular disease.

Conclusions Greater dietary fibre intake is associated with a lower risk of both cardiovascular disease and coronary heart disease. Findings are aligned with general recommendations to increase fibre intake. The differing strengths of association by fibre type or source highlight the need for a better understanding of the mode of action of fibre components.

From press release:

In recent years, a decline in both cardiovascular disease (CVD) and coronary heart disease (CHD) has been seen in some European countries and the United States. However, it still remains a significant issue accounting for almost half (48%) and a third (34%) of all deaths in Europe and the United States.

Many studies have examined the relationship between dietary fiber or fiber-rich foods and CVD risk factors.

Researchers at the University of Leeds reviewed literature published since 1990 in healthy populations concerning dietary fiber intake and CVD risk. They took data from six electronic databases. Cohorts of data were used from the US, Europe, Japan and Australia.

They looked at the following fiber intake: total, insoluble (whole grains, potato skins etc), soluble (legumes, nuts, oats, barley etc), cereal, fruit, vegetable and other sources.

Results from analyses of total, insoluble, fruit and vegetable fiber intake showed that the likelihood of a CVD or CHD event steadily lowers with increasing intake.

In soluble fiber, a higher reduction was seen in CVD risk than CHD risk and for cereal fiber, the reduced risk of CHD was stronger than the association with CVD.

A significantly lower risk of both CVD and CHD was observed with every additional 7g per day of fiber consumed. The researchers say these findings are aligned with current recommendations to increase fiber intake and demonstrate a large risk reduction with an achievable increase in daily fiber intake and say this could "potentially impact on many thousands of individuals."

They add that an additional 7g of fiber can be achieved through one portion of whole grains (found in bread, cereal, rice, pasta) plus a portion of beans / lentils or two to four servings of fruit and vegetables.

The researchers conclude that "diets high in fiber, specifically from cereal or vegetable sources ... are significantly associated with lower risk of CHD and CVD and reflect recommendations to increase intake." Greater intake from fruit fiber was associated with lower CVD risk. They recommend further work on the association with soluble or insoluble types of fiber.

In an accompanying editorial, Dr Robert Baron, Professor of Medicine at the University of California, says this study "increases our confidence that benefit, as reflected by reduced cardiovascular disease and coronary heart disease events, will in fact accrue with higher dietary fiber intakes."

He says that teaching patients to eat whole grains is still challenging, but that encouraging the increase of fiber gradually as well as drinking adequate amounts of water are other practical recommendations. The recommendation to consume diets with adequate amounts of dietary fiber "may turn out to be the most important nutrition recommendation of them all," he concludes.

Study Information

D. E. Threapleton, D. C. Greenwood, C. E. L. Evans, C. L. Cleghorn, C. Nykjaer, C. Woodhead, J. E. Cade, C. P. Gale, V. J. Burley
Dietary fiber intake and risk of cardiovascular disease: systematic review and meta-analysis
BMJ
2013 December
University of Leeds