The role of diet in multiple sclerosis onset and course: results from a nationwide retrospective birth‐year cohort

OBJECTIVE: To examine (1) the association between childhood diet and developing MS, age of onset and onset type and (2) the association between diet at age 50 and disability and MRI volumes in people with MS (PwMS). METHODS: The study enrolled 361 PwMS born in 1966 and 125 age‐ and sex‐matched healthy controls (HCs). Information on individual dietary components (fruit, vegetables, red meat, oily fish, whole‐grain bread and candy, snacks and fast food) and MS risk factors at the age of 10 and 50 years were collected using questionnaires. Overall diet quality score was calculated for each participant. Multivariable regression analyses were used to evaluate the association between diet at childhood and developing MS, age of onset and onset type and to evaluate diet at age 50, disability and MRI outcomes. RESULTS: Poorer overall diet quality and individual dietary components during childhood (less whole‐grain bread, more candy, snacks and fast food and oily fish) were associated with developing MS and onset type (all p < 0.05), but not with the age of onset. Fruit consumption at age 50 was associated with lower disability (Q3 vs. Q1: −0.51; 95% CI: −0.89 to −0.13). Furthermore, several individual dietary components at age 50 were associated with MRI volumetric measures. Higher‐diet quality at age 50 was only associated with lower lesion volumes in PwMS (Q2 vs. Q1: −0.3 mL; 95% CI: −0.5 to −0.02). INTERPRETATION: We demonstrate significant associations between dietary factors in childhood and developing MS, age of onset and onset type and between dietary factors at age 50 and disability and MRI‐derived volumes.