There is a significant association between low dietary fibre intake and cardiometabolic risks including metabolic syndrome, cardiovascular inflammation and obesity, according to a new study from Harvard Medical School in Boston.

The study, published on 16 October 2013 in The American Journal of Medicine, used surveillance data from 23,168 subjects in the National Health and Nutrition Examination Survey (NHANES) 1999-2010 to examine the role dietary fibre plays in heart health.

The researchers said the study highlighted the importance of increasing dietary fibre intake for US adults by showing a correlation between low dietary fibre and an increased risk for cardiovascular risk. Participants with the highest prevalence of metabolic syndrome, inflammation and obesity were in the lowest quintile of dietary fibre intake.

“Overall, the prevalence of the metabolic syndrome, inflammation and obesity each decreased with increasing quantities of dietary fibre intake,” said said Cheryl R. Clark, MD, ScD, from the Centre of Community Health and Health Equity, Brigham and Women’s Hospital and Harvard Medical School, Boston.

“Compared with participants in the lowest quintile of dietary fibre intake, participants in the highest quintile of dietary fibre intake had a statistically significantly lower risk of having the metabolic syndrome, inflammation and obesity,” Dr Clark said.

Demographics influence dietary fibre intake

Investigators used the data to take a closer look at possible sex, age, racial/ethnic and socioeconomic disparities in dietary fibre consumption, as well as examining the association between dietary fibre intake and various cardiometabolic risk factors.

Dietary fibre, which previous studies have shown may assist in lowering blood pressure, cholesterol levels and inflammation, is thought to play an important role in reducing cardiovascular risk. Despite this knowledge, investigators in the current study found that dietary fibre intake was consistently below recommended intake levels for the NHANES participants.

The Institute of Medicine in the US defines recommended intake levels according to age and sex: 38g per day for men aged 19-50 years, 30g per day for men 50 and over, 25g for women aged 19-50 years, and 21g per day for women over 50. However, using data from NHANES 1999-2010, the Harvard study revealed the mean dietary fibre intake was only 16.2g per day across all demographics during that time period.

“Our findings indicate that, among a nationally representative sample of non-pregnant US adults in NHANES 1999-2010, the consumption of dietary fibre was consistently below the recommended total adequate levels across survey years,” Dr Clark said. “Our study also confirms persistent difference in dietary fibre intake among socioeconomic status and racial/ethnic subpopulations over time,” she said.

The research team found variations according to race and ethnicity, with Mexican-Americans consuming higher amounts of dietary fibre and non-Hispanic black participants consuming lower amounts of dietary fibre, compared with non-Hispanic white participants.

Education on dietary fibre vital

Researchers said this new data analysis emphasised the importance of educating adults across diverse ethnicities to increase their dietary fibre intake in order to try and mitigate the risk for cardiovascular damage.

“Low dietary fibre intake from 1999-2010 in the US and associations between higher dietary fibre and a lower prevalence of cardiometabolic risks suggest the need to develop new strategies and policies to increase dietary fibre intake,” Dr Clark said. “Additional research is needed to determine effective clinical and population-based strategies for improving fibre intake trends in diverse groups,” she said.

Institutional financial support for the study was provided by Partners HealthCare and the Brigham and Women’s Hospital Centre for Community Health and Health Equity. CRC was supported by funding from the National Institute on Ageing.

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