Objective: The potential role of nutritional factors in multiple sclerosis (MS) etiology is not clearly understood. The authors investigated the association between dietary intake during adolescence with MS. Design, setting and participants: This was a population-based incident case-control study in Iran with 547 incident cases and 1057 general population controls (7/8/2013-17/2/2015). Logistic regression was used to test differences in dietary intake between cases and controls adjusted for confounders. Results: We found that a higher dietary consumption during adolescence of fresh fish, canned tuna, poultry, cheese, yogurt, butter, fruit, vegetables and a number of dietary supplements were associated with a significantly reduced risk of MS, while red meat, shrimp, and margarine were not associated with MS. Fresh fish had a dose-response association of 0.71 (0.58-0.88) per category increase, and consuming >0.5 serves of canned tuna fish per week had an OR of 0.72 (0.56-0.90); fruit intake had an OR of 0.82 (0.71-0.94) per category increase and cheese consumption an OR of 0.78 (0.67-0.91) per category increase. Conclusions: We identified that a higher intake of a number of food groups generally viewed as healthy were associated with a reduced risk of MS. A healthier diet during adolescence may be protective of developing MS.