There is an inverse relation between omega-3 fatty acids and ALS
ALS (amyotrophic lateral sclerosis) is a potentially life-threatening disease that affects the spinal cord and the motor nerves of the brain. The disease is incurable but according to an American study that is published in Neurology, it progresses at a slower rate in patients with a higher intake of omega-3 fatty acids from different dietary sources.
Typical symptoms of ALS are increasing weakness in the arms and legs and problems with swallowing and speaking. The disease progresses over time, and it may result in musculoskeletal pain, mucous in the respiratory tract, breathing difficulty, and personality changes. In the final stage of the disease, many patients are paralyzed or bedridden. The average survival time after being diagnosed with ALS is three years. In most cases, the underlying cause is unknown, but in 5-10 percent of cases it is caused by hereditary factors. ALS is related to abnormal immune reactions in the central nervous system that can damage the nerve cells. There is no cure for ALS, which is why there is an urgent need to discover ways to prevent the disease and its development.
The new study included 449 patients who had been diagnosed with ALS. Their mean age was 58 years, and they were followed for a period of 18 months. During the study period, 126 patients (28%) died.
The scientists looked closer at the patients’ blood levels of omega-3 fatty acids and divided the participants into four groups, depending on how much or little omega-3 they had in their blood.
The patients’ symptoms were also assessed. The test looked at 12 aspects of physical function such as speech, the ability to swallow, breathing, and muscle control in the hands, arms, legs, and body. A higher score meant better functions and fewer symptoms.
The more omega-3, the better the prognosis
It turned out that patients with the highest levels of the omega-3 fatty acid ALA (alpha-linolenic acid) had a higher score on average compared with patients with the lowest levels. ALA is found naturally in plant sources such as linseed oil, rapeseed oil, hemp oil, walnuts, and chia seeds. In addition, there were fewer deaths among those with more ALA in their blood (21 patients) compared with those who had the lowest amounts (37).
After adjusting for possible confounders such as age, gender, and ethnicity, the scientists could see that patients with the most ALA in their blood had a 50% lower risk of dying during the study period compared with those who had the least ALA in their blood.
The researchers also observed that the omega-3 fatty acid, EPA (eicosapentaenoic acid), that is found in oily fish and fish oil supplements was associated with a lower risk of dying during the study period. They also found that the omega-6 fatty acid called LA (linoleic acid) that is found in most plant oils, nuts, kernels, and eggs was linked to a lower risk of dying.
The study got funding from the ALS Association. According to the team of scientists, the different omega-3 and omega-6 fatty acids have the potential to slow down the disease progression and help the patients live longer. Still, the study has certain limitations. The researchers point out that they lack data about the participants’ general diet habits, their calorie intake, and their use of other supplements, all of which may also affect the life expectancy after being diagnosed with ALS.
How do omega-3 and omega-6 fatty acids affect the brain and nervous system?
Omega-3 and omega-6 belong to the group of polyunsaturated fatty acids that are structural components of cell membranes. Here, they help regulate different biochemical processes. Omega-3 and omega-6 fatty acids work together in a complicated biochemical interplay, and it is vital to get them in the right balance. The brain contains comparatively large quantities of the two different fatty acids, and they are of vital importance to the nervous system and its functions.
Previous studies have shown that the polyunsaturated fatty acids support and protect the nerve cells, especially the type of omega-3 called EPA that is anti-inflammatory.
Published population studies have demonstrated that increased intake of the two fatty acids and having higher levels of them in the blood is linked to a reduced risk of developing ALS, especially with regard to ALA. Nonetheless, there is limited data on the effect on ALS and the disease progression. The new study, which is published in the science journal Neurology, sheds new light on how blood levels of the two polyunsaturated fatty acids can help predict the course and prognosis of the ALS disease.
How much omega-3 and omega-6 do we need?
According to the Danish health authorities, 5-10 percent of our energy intake should ideally come from polyunsaturated omega-3 and omega-6 fatty acids. The intake of omega-3 should represent at least one percent of the total energy intake. Depending on a person’s need for energy, this is the equivalent of consuming 2.4 – 3.6 grams of omega-3 per day (for an adult). Half of this should come from ALA, according to the guidelines.
Unfortunately, modern diets typically contain too much omega-6 from plant oils that have been destroyed through industrial processing, deep-frying, and other heating methods. Our diets also contain far too little omega-3 because we don’t eat enough fish and vegetable sources of omega-3 such as walnuts, linseeds, chia seeds, and rapeseed oil. Linseed oil has a very high ALA content so be careful not to get too much. Many people have difficulty with converting ALA into EPA and DHA in the body.
ALA content (grams per 100 grams of food) in different vegetable sources
Linseed oil: 53
Rapeseed oil: 9
Chia seeds: 19
EPA and DHA content (grams per 100 grams) in various fish and fish products
Canned cod liver: 11
Mackerel in tomato sauce: 2.6
Herring, pickled/smoked 1.8 - 2.8
Rainbow trout: 1.3
Wild salmon: 1.3 – 3.0
Farmed salmon: 1.1
Cod roe: 0.4
Shrimp and tuna: 0.3
Cod: 0. 2
Kjetil Bjornevik et al. Association of Polyunsaturated Fatty Acids and Clinical Progression in Patients With ALS: Post Hoc Analysis of the Empower Trial. Neurology 2023
Gina Mantica. New Insights into ALS. Harvard Medical School. 2023
Amyotrofisk lateral sklerose (ALS) - Patienthåndbogen på sundhed.dk
Omega-3 fedtsyrer - Fødevarestyrelsen (foedevarestyrelsen.dk)
Frida - Parametre (fooddata.dk)
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