Association of Dietary Inflammatory Index, Diversity, and Micronutrient Adequacy with Rheumatoid Arthritis: A Matched Case-Control Study

BackgroundRheumatoid Arthritis (RA), a chronic autoimmune disease, is influenced by genetic and environmental factors, including diet. This matched case &[ndash]control study examined the association of nutritional status (nutrient adequacy, dietary diversity score [DDS]) and the Dietary Inflammatory Index (DII) with RA onset and autoantibodies in a population from Hyderabad, India. MethodologyA total of 301 RA patients and 314 age &[ndash] and sex &[ndash]matched healthy controls were recruited. Dietary intake was assessed using a validated 131 &[ndash]item food frequency questionnaire (FFQ). DII was used to measure dietary inflammation, while DDS and micronutrient adequacy probability assessed dietary quality. Autoantibodies (rheumatoid factor [RF] and anti &[ndash]CCP) were measured using ELISA. Multivariate regression models adjusted for age, sex, and BMI were used to examine associations, and population attributable fractions (PAFs) were estimated. ResultsRA cases had lower micronutrient adequacy (33% vs. 45%), lower median DDS (5.00 vs. 6.00), and higher median DII (0.84 vs. 0.26) compared to controls. Each one &[ndash]unit increase in DII increased RA likelihood by 42% [AOR: 1.42(1.21, 1.67)], while a one-unit increase in DDS reduced RA odds by 39% [AOR: 0.61(0.53, 0.70)]. A 1% increase in micronutrient adequacy reduced RA odds by 2% [AOR: 0.98(0.97, 0.99)]. Lower DDS and micronutrient inadequacy were linked to higher RF and anti &[ndash]CCP levels. The PAFs for higher DII, poor DDS, and nutrient inadequacy were 38.0%, 35.5%, and 39.9%, respectively. ConclusionHigher dietary diversity and micronutrient adequacy reduced RA likelihood, while higher DII increased RA likelihood, highlighting the role of diet in RA and autoimmunity.