ALS is a rare, progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. People with ALS lose the ability to initiate and control muscle movement, which often leads to total paralysis and death. The average life span after diagnosis is two to five years.

"The link our study found between diet and ALS is intriguing and suggests, but does not prove, that people with ALS may benefit from incorporating more omega-3 fatty acids into their diet," said Kjetil Bjornevik, MD, PhD, of Harvard University in Boston, Massachusetts, and member of the American Academy of Neurology. "It will now be important to conduct additional research looking specifically at the plant-based omega-3 fatty acid alpha-linolenic acid in people with ALS to further explore this possibility."

The study involved 449 people who had ALS with an average age of 58, who were followed over 18 months. Of the total participants, 126 or 28%, died by the end of the study.

Researchers looked at levels of omega-3 fatty acids in participants' blood. They divided them into four groups based on lowest to highest amounts.

Participants took a test to assess their disease progression and severity of symptoms. The test measured 12 aspects of physical function including swallowing, speaking, chewing, and the ability to use muscles in the hands, arms, legs and torso, as well as respiratory function. Each category was scored from zero, meaning no ability, to four, meaning normal ability. Total scores ranged between zero to 48, with higher scores indicating better function and less severe symptoms.

Researchers found an omega-3 fatty acid called alpha-linolenic acid was the most beneficial. This acid is found in many seeds and oils, including flaxseed, walnuts, chia, hemp, and many common vegetable oils.

The people with the highest amount of alpha-linolenic acid had an average score of 38.3 at the start of the study, while the people with the lowest amount had an average score of 37.6.

A lower number of people from the group with the most alpha-linolenic acid died during the study, with 21 deaths, or 19%, compared to people in the lowest group, with 37 deaths or 33%.

After adjusting for age, sex and ethnicity, people with the highest amounts of alpha-linolenic acid had a 50% lower risk of death during the study compared to people with the lowest amount.

Higher levels of a specific omega-3 fatty acid called eicosapentaenoic acid that is found in fatty fish and fish oil supplements was also associated with a lower risk of death during the study.

此外,研究人员发现一种ω- 6脂肪酸acid called linoleic acid that is found in vegetable oils, nuts, meats, seeds and eggs was associated with a lower risk of death during the study.

A limitation of the study is the lack of access to data on the overall diet of the participants, including other nutrients and supplements as well as total caloric intake, which could all be associated with survival time in ALS.

The study was supported by the ALS Association.