Serum Alpha-Linolenic Acid and Long-Term Multiple Sclerosis Activity and Progression.

BACKGROUND AND OBJECTIVES Higher dietary intake of alpha-linolenic acid (ALA), a plant-derived omega-3 polyunsaturated fatty acid (PUFA), was associated with a lower risk of multiple sclerosis (MS) in a prospective cohort study and lower risk of new lesions, relapses, and disability progression in a patient cohort. We examined whether serum levels of ALA and other PUFAs predicted MS outcomes up to 11 years after clinical onset. METHODS This prospective study was conducted among participants in the BENEFIT clinical trial, who had serum samples collected starting at randomization. Serum fatty acids were measured using gas chromatography. We evaluated the association of individual fatty acids with time to clinically definite MS (CDMS) and other measures of disease activity and progression using Cox, negative binomial, and linear regression. RESULTS We followed 468 participants for 5 years, including 278 followed to year 11. At baseline, the median age was 30 years and 71% were women. Higher baseline serum ALA levels were associated with a lower risk of CDMS and relapses during follow-up. The multivariable-adjusted hazard ratios for CDMS comparing top to bottom quartile were 0.60 (95% CI 0.39-0.95) and 0.60 (95% CI 0.37-0.98) after 5 and 11 years, respectively. The multivariable adjusted risk ratios for relapses comparing top to bottom quartile were 0.60 (95% CI 0.38-0.94) and 0.65 (95% CI 0.43-0.99) after 5 and 11 years, respectively. None of the other 35 fatty acids were associated with CDMS risk. Three fatty acids were associated with relapse rate after 5 years, but not 11 years. Higher ALA levels were associated with a slower decline in MS Functional Composite, an assessment of disability, at 5 years. The association was similar at 11 years, but the results did not retain statistical significance. Baseline ALA levels were not associated with subsequent changes in cognitive function, time to confirmed Expanded Disability Status Scale progression, new active lesions, or brain volume loss. DISCUSSSION Higher serum ALA levels were associated with a lower risk of CDMS, relapses, and disability progression in a large prospective cohort. The results were null or inconsistent for other fatty acids.