Higher fiber intake reduces inflammation, CVD risk in older adults

ByMaria Marabito

Higher fiber intake, specifically cereal fiber, was associated with lower levels of inflammation and a reduced risk for CVD in older adults, according to findings published in JAMA Network Open.

“This is interesting as it suggests that cereal fiber, more so than vegetable or fruit fiber, may be most useful to reduce inflammation and/or CVD risk; this will, however, need to be confirmed in future interventional studies,” Rupak Shivakoti, PhD, an assistant professor of epidemiology in the Mailman School of Public Health at Columbia University, told Healio.

CVD risk was lower in older adults who consumed an additional 5 g/d — Shivakoti R, et al. *JAMA Netw Open*. 2022;doi:10.1001/jamanetworkopen.2022.5012.

Shivakoti and colleagues assessed the association between dietary fiber intake and inflammation as well as incident CVD among 4,124 older adults in the U.S. who were enrolled in the Cardiovascular Health Study from 1989 to 1990. The mean age of the participants was 72.6 years; 60% were women, 95% were white and 4.4% were Black.

At baseline, the participants gave fasting blood samples and completed a 99-item, picture-sort version of the National Cancer Institute food frequency questionnaire, which Shivakoti and colleagues used to estimate participants’ fiber intake. Follow-up visits (in person and telephone) were scheduled every 6 months from baseline to 1999. After 1999, telephone follow-ups continued every 6 months to 2015.

Rupak Shivakoti

Fiber intake

Overall, the mean energy-adjusted total fiber intake of the participants was 16.3 g/d, according to Shivakoti and colleagues. Specifically, the mean energy-adjusted cereal fiber intake was 4.2 g/d, the mean vegetable fiber intake was 6.9 g/d and the mean fruit fiber intake was 5.2 g/d.

“A substantial proportion of individuals in this study, particularly those in the lower quartiles, have fiber intakes below the recommended amounts,” Shivakoti said. “Thus, increasing intakes of foods higher in dietary fiber in these individuals could potentially improve their health.”

The National Resource Center on Nutrition and Aging recommends 21 g/d to 30 g/d of fiber for adults aged 51 years and older, and 25 g/d to 38 g/d for younger adults. The recommended adequate intakes for fiber are based on the amounts needed for protection against heart disease, according to the center.

Men, Black individuals, those who had less than a high school education, current or former smokers, frequent drinkers and those who exercised infrequently had lower total fiber, vegetable and fruit intakes, according to the researchers.

Associations with CVD and inflammation

During a median follow-up of 11.9 years, the researchers recorded 1,941 CVD events. They found that consuming 5 g/d more of total fiber (HR = 0.95; 95% CI, 0.91-0.99) and cereal fiber (HR = 0.86; 95% CI, 0.79-0.95) were associated with a lower risk for CVD.

Shivakoti and colleagues also reported that consuming 5 g/d more of total fiber was associated with significantly lower concentrations of C-reactive protein (adjusted mean difference [aMD] = 0.05; 95% CI, 0.08 to 0.01) and interleukin-1 receptor antagonist (aMD = 0.04; 95% CI, 0.07 to 0.01). In addition, an increase in total fiber intake of 5 g/d was associated with significantly higher concentrations of soluble CD163 (aMD = 0.05; 95% CI, 0.02-0.09).

Higher intakes of vegetable or fruit fiber did not significantly affect inflammation or CVD risk, according to the researchers. However, an increase in cereal fiber intake of 5 g/d was associated with significantly lower concentrations of C-reactive protein (aMD = 0.12; 95% CI, 0.18 to 0.05), interleukin 6 cytokines (aMD = 0.08; 95% CI, 0.15 to 0.02 SD) and interleukin-1 receptor antagonist (aMD = 0.1; 95% CI, 0.17 to 0.04).

“These results suggest that ... cereal fibers might be more effective in reducing systemic inflammation,” Shivakoti and colleagues wrote.

However, the researchers are not able to say whether it is cereal fiber itself or other components in foods high in cereal fiber that are driving this association, according to Shivakoti.

“Given that unresolved inflammation is associated with both an increased risk of multiple diseases and their outcomes, studies should investigate the specific mediating effect of inflammation on these outcomes,” they added.