In the study, published in July in JAMA Neurol and conducted by Harvard researchers, the 20% of consumers who had highest levels of omega-3 fatty acid in their diet were a third less likely develop the fatal disease compared with the 20% who ate the lowest amount of omega-3s.
Amyotrophic lateral sclerosis (ALS), known in America as Lou Gehrig's disease, is a rapidly progressive neurological disease that attacks the nerve cells responsible for controlling voluntary muscles. It is one of the most common neuromuscular diseases worldwide, and people of all races and ethnic backgrounds are affected. Renowned physicist Professor Stephen Hawking is a sufferer of the condition.
The study, led by Kathryn Fitzgerald at Harvard School of Public Health, examined the association of ω-3 and ω-6 PUFA consumption and ALS risk in an analysis of data gathered from more than one million people who had participated in five previously published studies.
They knew that diet-derived long-chain polyunsaturated fatty acids (PUFAs) are incorporated in brain lipids and modulate oxidative and inflammatory processes and could thus affect ALS risk and progression, although there was little data available.
Researchers documented 995 ALS cases during follow-up, which ranged from nine to 24 years. A greater ω-3 PUFA intake was associated with a reduced risk for ALS. Consuming both α-linolenic acid (ALA, which can be found in plant sources and nuts) and marine ω-3 PUFAs contributed to this association. Intake of ω-6 PUFAs was not associated with ALS risk.
Diet was assessed through questionnaires. For men, median ω-3 PUFA intake ranged from 1.40 to 1.85 grams(g)/day(d) and median ω-6 PUFA intake ranged from 11.82 to 15.73 g/d. For women, median ω-3 intake ranged from 1.14 to 1.43 g/d and median ω-6 PUFA intake ranged from 8.94 to 12.01 g/d.
"Overall, the results of our large prospective cohort study suggest that individuals with higher dietary intakes of total ω-3 PUFA and ALA have a reduced risk for ALS,” the paper said.
Further research, possibly including biomarkers of PUFA intake, should be pursued to confirm these findings and to determine whether high ω-3 PUFA intake could be beneficial in individuals with ALS, the researchers suggest.
The research was supported by grants from the National Institute of Neurological Diseases and Stroke, the National Cancer Institute and the ALS Therapy Alliance Foundation.
Michael Swash, M.D., of the Royal London Hospital, England, said: "Fitzgerald and colleagues suggest that the fatty acid composition of cell plasma membranes, which could be measured in red cell membranes, might be important in modulating oxidative stress responses, excitotoxicity and inflammation, all factors that have been implicated in ALS and other neurodegenerative conditions."
"As a note of caution and in contrast to their results, the authors note that in a mouse model of ALS pretreatment with high doses of eicosapentanoic acid, a long-chain ω-3 PUFA, accelerated disease progression," Swash added.
‘Dietary ω-3 Polyunsaturated Fatty Acid Intake and Risk for Amyotrophic Lateral Sclerosis’
Authors: Kathryn C. Fitzgerald, MSc; Éilis J. O’Reilly, ScD; Guido J. Falcone, MD; et al.