Dietary inflammatory index and risk of multiple sclerosis: Findings from a large population-based incident case–control study

Background & aims: For many decades diet, mainly its “pro-inflammatory” quality has been pondered as a possible risk factor for developing MS. However, the complexity of different dietary composition analysis provided controversial results. Recently a dietary inflammatory index (DII), a population-based score, was developed to objectify the inflammatory characteristics of a specific dietary intake. Methods: We investigated the potential association between DII (expressed as energy adjusted-DII (E-DII) and non-energy adjusted DII (DII)) assessed from a validated FFQ based on the participants' diet habits during adolescence and the risk for developing MS in a population-based incident case–control study. Multiple logistic regression was used to estimate the adjusted. Results: We recruited 547 incident MS cases and 1057 general population controls from Tehran, Iran (August 2013–February 2015). A statistically significant higher risk of MS was found in analyses using E-DII scores as a continuous variable with an adjusted odds ratio (AOR) of 1.53 (95% confidence interval (CI): 1.42–1.65, P = 0.001), and as a categorical variable (4th quartile OR 7.01, 95% CI: 4.87–10.1, vs the first quartile), test for trend; OR 1.86 (95% CI: 1.67–2.07), P for trend <0.001. A similar pattern was demonstrated for DII score and risk for MS. Conclusions: We identified a pro-inflammatory diet characterized by higher E-DII and DII scores during adolescence as a strong risk factor for MS onset. Given the worldwide role of diet in general population health, improving nutritional pattern through educational programs is likely to reduce MS risk.