Intake of polyunsaturated fatty acids and vitamin E reduces the risk of developing amyotrophic lateral sclerosis

Background: To assess whether the premorbid dietary intake of fatty acids, cholesterol, glutamate or antioxidants was associated with the risk of developing amyotrophic lateral sclerosis (ALS). Methods: Patients referred to our clinic during 2001-2002, who had definite, probable or possible ALS according to El Escorial criteria, without a familial history of ALS, were asked to participate in a case-control study (132 patients and 220 healthy controls). A food-frequency questionnaire was used to assess dietary intake for the nutrients of interest. Multivariate logistic regression analysis was performed with adjustment for confounding factors (sex, age, level of education, energy intake, body mass index and smoking). Results: A high intake of polyunsaturated fatty acid (PUFA) and vitamin E was significantly associated with a reduced risk of developing ALS (PUFA: odds ratio (OR) = 0.4, 95% confidence interval (CI) = 0.2 to 0.7, p = 0.001; vitamin E: OR = 0.4, 95% CI = 0.2 to 0.7, p = 0.001). PUFA and vitamin E appeared to act synergistically, because in a combined analysis the trend OR for vitamin E was further reduced from 0.67 to 0.37 (p = 0.02), and that for PUFA from 0.60 to 0.26 (p = 0.005), with a significant interaction term (p = 0.03). The intake of flavonols, lycopene, vitamin C, vitamin B-2, glutamate, calcium or phytoestrogens was not associated with the risk of developing ALS. Conclusion: A high intake of PUFAs and vitamin E is associated with a 50-60% decreased risk of developing ALS, and these nutrients appear to act synergistically.