Consumption of omega-3 fatty acids and alpha-linolenic acid contribute to the delay
Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. Early symptoms of ALS often include increasing muscle weakness, especially involving the arms and legs, speech, swallowing or breathing.
Approximately 5,600 people in the U.S. are diagnosed with ALS each year. The incidence of ALS is two per 100,000 people, and it is estimated that as many as 30,000 Americans may have the disease at any given time. It is estimated that ALS is responsible for nearly two deaths per hundred thousand population annually.
ALS is a severe progressive disease that cannot be prevented or cured. 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.
In this new study Kathryn Fitzgerald, MSC, Department of Nutrition, Harvard School of Public Health in Boston and lead researcher along with colleagues examined the association between ω-6 and ω-3 PUFA consumption and ALS risk.
The analysis was based on 1,002,082 participants (479,114 women and 522,968 men) from five prospective cohorts; he National Institutes of Health–AARP Diet and Health Study, the Cancer Prevention Study II Nutrition Cohort, the Health Professionals Follow-up Study, the Multiethnic Cohort Study, and the Nurses’ Health Study. Diet was assessed via food frequency questionnaire developed or modified for each cohort. The follow-up period ranged from 9-25 years, depending on the study group.
Researchers documented 995 cases of ALS during the follow-up. A greater ω-3 PUFA intake was associated with a reduced risk for ALS. Consuming both α-linolenic acid ( which can be found in foods including flaxseeds, flaxseed oil, canola (rapeseed) oil, soybeans and soybean oil, pumpkin seeds and pumpkin seed oil, perilla seed oil, tofu, walnuts, and walnut oil) and marine ω-3 PUFAs contributed to this association. Intake of ω-6 PUFAs was not associated with ALS risk.
Participants that were ranked in the top 20% in terms of their omega 3 intake reduced the risk of developing ALS by one-third in comparison to those in the bottom 20%.
In their discussion the research team writes “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. 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 research team found no significant evidence that BMI, carotenoids, smoking status and vitamin E supplements reduced the risk of ALS.
Lead researcher Kathryn Fitzgerald commented "individuals with higher dietary intakes of total omega-3 polyunsaturated fatty acids -- an essential type of dietary fat found in vegetable oils and fish -- had a reduced risk for ALS. ‘"We also found that higher dietary intake of alpha-linolenic acid, a type of fatty acid found in vegetable oils and nuts, is also associated with lower ALS risk,”, as reported by WebMD.
In an editorial, Dr. Michael Swash, MD, MB,BS, FRCP, FRCPath, RSM, Consultant Neurologist and Profesor of Neuropathology, The Royal London Hospital writes “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,” the author continues.
“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 notes.
This study was published online July 14 in JAMA Neurology.