In a recently published study, Dr Scientific reportResearchers have investigated the relationship between dietary fiber and the risk of rheumatoid arthritis (RA).
RA is a common inflammatory disorder that damages joints and causes functional impairment. The global prevalence of RA has been increasing at an annual rate of 8.2% since 1990, highlighting the need for improved diagnosis and prevention strategies. Although the etiology of RA remains complex and less defined, studies have suggested that dietary factors may potentially contribute to RA development.
Reports suggest that dietary fiber may have therapeutic effects against inflammatory disorders. Several benefits of higher fiber consumption have been reported, including reduced systemic inflammation in RA subjects. Inflammation is an important factor in RA development, and the dietary inflammatory index (DII) is an important tool to assess the overall inflammatory potential of a diet.
About the study
The present study investigated associations of dietary fiber intake with RA risk. The team used data from the National Health and Nutrition Examination Survey (NHANES) conducted in the United States (US) between 2011 and 2020. The survey, representative of the non-institutionalized US population, was conducted by the National Center for Health Statistics.
Participants with extreme energy intake, missing (covariate and dietary intake) data and those without RA data were excluded. A nutritionist conducted two 24-hour dietary recall sessions: an in-person session and a telephone session 3–10 days apart. Average fiber intake was estimated, and sources of dietary fiber included fruits, vegetables, and grains.
A questionnaire was administered to investigate participants’ arthritis or RA status. Further, the team estimated the DII score by evaluating dietary markers. Covariates were age, sex, body mass index (BMI), race, menopausal status, energy intake, alcohol status, smoking status, education, waist circumference, family income-poverty ratio, and physical activity.
Demographic data were stratified by RA status and evaluated using t- and chi-square tests. Logistic regression methods were applied to explore the relationship between fiber intake, inflammatory markers and RA prevalence. The mediating role of DII in the relationship between RA onset and fiber intake was examined.
Of the 32,451 NHANES respondents from 2011–20, 15,114 subjects were retained for analysis, following exclusion criteria. The mean age of participants at the time of assessment was 46.37, and approximately 7% had RA. Mean total fiber intake was 15.37 g/day among RA subjects and 17.12 g/day among those without RA. Individuals with RA were predominantly female, older, and had higher BMI and lower education and income than non-RA subjects.
Participants with RA were less likely to smoke, consume alcohol, and engage in physical activity. The team observed an inverse relationship between total fiber intake and RA onset. Additionally, fiber intake was stratified into tertiles in sensitivity analyses. It revealed that individuals in the top-best tertile (of fiber intake) had a one-quarter reduction in RA compared to those in the lowest tertile.
Moreover, among sources of dietary fiber, cereal fiber intake had a significant inverse association with RA, which was more evident in a sensitivity analysis. In contrast, the association of fruit and vegetable fiber with RA was uncertain. The researchers noted that total fiber intake was significantly associated with DII and high-sensitivity C-reactive protein.
There was a similar trend for vegetable or cereal fiber intake. A positive correlation was observed between DII and RA prevalence, indicating a 26% increase in RA prevalence with a one-unit increase in DII. Data suggested a mediating role of DII in the association between fiber intake (36.12% for total fiber intake and 40.35% for cereal fiber intake) and RA incidence.
Findings revealed an association between suboptimal fiber intake and higher RA incidence. DII was identified as an important mediator in this association. Although DII provides a comprehensive assessment of the inflammatory potential of a diet, it is worth noting that several dietary components can influence DII. Furthermore, dietary recall methods have limitations, such as poor precision and over- or under-reporting.
- Wan H, Zhang Y, Ning Z, Liu M, Yang S. Association of cereal fiber intake with rheumatoid arthritis mediated by dietary inflammatory indices: insights from NHANES 2011–2020. Science representative2024. doi:10.1038/s41598-024-52806-w https://www.nature.com/articles/s41598-024-52806-w