Nutritional factors in the aetiology of multiple sclerosis: a case-control study in Montreal, Canada

Background It has been suggested that nutrition and food patterns, particularly high consumption of animal fat and low intake of fish products, may play a role in the aetiology of multiple sclerosis (MS). Methods The relation between nutritional factors and MS was studied among 197 incident cases and 202 frequency matched controls in metropolitan Montreal during 1992-1995. Dietary information was collected by employing a 164-item food frequency questionnaire in a face-to-face interview. Results An inverse association was observed between high body mass index (BMI) and the risk of MS, with an odds ratio (OR) of 0.76 (95% confidence interval [CI] : 0.61-0.95), per 5-unit increase in BMI, both sexes combined. In addition, taller women showed a greater risk for MS; the OR per 10 cm increase in height was 1.58 (95% CI: 1.06-2.35). In continuous variable analyses, using the difference between the lowest and highest quartile of intake as a unit, a positive association was observed with energy and animal fat intake. The OR per 897 kcal increase was 2.03 (95% CI: 1.13-3.67) and 1.99 (95% CI: 1.12-3.54) per 33 g of animal fat intake above the baseline. A significant protective effect was observed with other nutrients, including vegetable protein, dietary fibre, cereal fibre, vitamin C, thiamin, riboflavin, calcium, and potassium. Similar trends were seen for males and females when analysed separately. With respect to specific foods (as opposed to nutrients), a higher intake of fruit juices was inversely associated with risk (OR = 0.82; 95% CI:0.74-0.92). A protective effect was also observed with cereal/breads intake for all cases combined (OR = 0.62; 95% CI:0.40-0.97) and for fish among women only; pork/hot dogs (OR = 1.24; 95% CI: 1.02-1.51) and sweets/candy (OR = 1.29; 95% CI: 1.07-1.55) were positively associated with risk. Conclusion The study generally supports a protective role for components commonly found in plants (fruit/vegetables and grains) and an increased risk with high energy and animal food intake.