Low Dietary Fiber Increases Cardiometabolic Risk

Results of a recent study from researchers at the Brigham and Women’s Hospital in Boston, Massachusetts, have demonstrated a significant association between low dietary fiber intake and cardiometabolic risks, including metabolic syndrome, cardiovascular inflammation, and obesity; a consistently low fiber consumption among study participants; and significant differences in dietary fiber intake by sex, racial/ethnicity, and socioeconomic status. 

Previous studies have shown that dietary fiber intake may lower one’s risk of cardiovascular disease and associated risk factors. “To date, recent studies have not fully investigated potential demographic and socioeconomic disparities in dietary fiber intake over time, or the relation between dietary fiber intake and cardiometabolic risk factors in diverse populations,” the authors write. 

Using data from the 1999-2010 National Health and Nutrition Examination Survey (NHANES), Cheryl R. Clark, MD, ScD, Center for Community Health and Health Equity at Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, and colleagues examined the relationship between dietary fiber intake and cardiometabolic risk factors, including metabolic syndrome, obesity, and cardiovascular inflammation, in diverse groups of US adults; the possible age, sex, racial/ethnic, and socioeconomic disparities in dietary fiber intake; and the secular trends in dietary fiber intake among US adults during this time period. 

The authors performed a cross-sectional analysis of 23,168 men and nonpregnant women (aged ≥20 years) from the 1999-2010 NHANES, a cross-sectional, nationally representative sample of the US noninstitutionalized civilian population. Weighted multivariable logistic regression models were used to estimate predicted marginal risk ratios and 95% confidence intervals for the risks of the metabolic syndrome, inflammation, and obesity associated with quintiles of dietary fiber intake. 

The Institute of Medicine (IOM) recommends the following adequate intake levels for total fiber: 38 g per day for men aged 19-50 years, 30 g per day for men older than 50 years, 25 g per day for women aged 19-50 years, and 21 g per day for women older than 50 years. In their study, Clark and colleagues found that the mean dietary fiber intake among the total population was only 16.2 g per day, well below the IOM total recommended adequate intake levels. 

Further, individuals who consumed higher amounts of dietary fiber were more likely to be older (≥51 years), male, Mexican-American, highly educated (bachelor’s degree or greater), former smokers, and physically active, as compared with those who consumed lower amounts of dietary fiber. 

After adjusting for age, total energy intake, sex, race/ethnicity, education, and smoking status, researchers found that individuals with higher intakes of dietary fiber had a statistically significant lower risk of having the metabolic syndrome, inflammation, and obesity. 

Finally, increasing dietary fiber intake was associated with statistically significant decreases in the prevalence of inflammation among all racial and ethnic groups, and statistically significant decreases in obesity and metabolic syndrome risks were seen only among whites.

“Our findings are consistent with prior literature suggesting a lack of improvement in US dietary fiber intake trends over time, as well as sociodemographic differences in fiber intake,” the authors write. “These data support prior recommendations to improve strategies that increase dietary fiber intake among US adults.” 

“Additional nutritional policies may be needed to increase adequate consumption of dietary fiber, in order to reduce cardiometabolic risk factors in diverse US populations.” 

Funding information for this study is available online in the American Journal of Medicine. 

-Meredith Edwards White 

Reference 

Grooms KN, Ommerborn MJ, Pham DQ, Djoussé L, Clark CR. Dietary fiber intake and cardiometabolic risks among US adults, NHANES 1999-2010. Am J Med. 2013 Oct 9. pii: S0002-9343(13)00631-1. doi: 10.1016/j.amjmed.2013.07.023. [Epub ahead of print]