Fish oil can lower the risk of Alzheimer’s disease

Alzheimer’s disease is an ailment that takes years to develop. More and more people are affected by this condition, which is the main cause of dementia. Diet and lifestyle play a major role, and it appears that daily supplementation with fish oil can significantly reduce the risk – especially in those who are genetically predisposed for the disease. This was shown in a new study that is published in JAMA Network Open.

It is commonly known that Alzheimer’s disease involves a build-up of harmful protein in the brain, which can lead to cell damage. Also, researchers have found lesions in the white matter of the brain, which consists of white, cholesterol-containing myelinated nerve fibers. The myelination of the long fibers of nerve cells serves as a type of insulation that speeds up the transmission of electric signals, so this is important for cognitive skills and many other functions. In the new study, the scientists wanted to investigate if fish oil supplements could reduce the lesions in the white matter and improve neural integrity in seniors.
The study included 102 women and men aged 75 years and older, who had relatively low blood levels of omega-3 fatty acids (EPA and DHA), both of which are found in fish oil. Half of the participants were supplemented with 1.65 grams of omega-3 fatty acids daily (975 mg of EPA and 650 mg of DHA), while the other half got a soy oil placebo that tasted, smelled, and looked exactly like the fish oil capsules. The researchers measured levels of the APOE*E4 gene (apolipoprotein) in all participants. This gene is known to double a person’s risk of Alzheimer’s disease.
The randomized clinical study lasted three years and showed that fish oil supplementation significantly reduces the lesions in the white brain matter in carriers of the APOE*E4 gene. Based on their findings, the researchers concluded that fish oil is particularly relevant for this group of people.

Large study shows that fish oil supplements reduce the risk by nearly 50%

The new study supports an earlier and much larger population study that is published in Nutrients. This trial included nearly 1,500 participants aged 65 years and older, who were free of dementia at baseline. However, as the study unfolded over a seven-year course, it turned out that the quintile of participants with the highest levels of the omega-3 fatty acid DHA in their blood were 49 percent less likely to develop Alzheimer’s disease, compared with the quintile with the lowest amounts of DHA in their blood. The scientists observed that participants who were carriers of the APOE*E4 gene benefited the most from having high blood levels of DHA.
The scientists therefore concluded that high-dosed intake of omega-3 fatty acids from oily fish or from fish oil supplements contributes to the prevention of Alzheimer’s disease and helps slow down its progression in cases where the disease has already occurred.

How do omega-3 fatty acids affect brain health?

The polyunsaturated omega-3 fatty acids occur in different forms. We need the two forms called EPA and DHA, as they are structural components of cell membranes and have a variety of different physiological functions. Brain cells contain a lot of DHA that is important for the nerve synapses, where information is exchanged between nerve cells. EPA and DHA also increase the flow of blood and counteract chronic brain inflammation.

Why do so many people lack omega-3?

Modern diets contain far less omega-3 than earlier. This is because we eat less oily fish, which is the best source of EPA and DHA. Farmed fish that eat unnatural fodder have far less omega-3 in their meat. We also get far too much omega-6 from plant oils, margarine, and industrially processed food, and that throws the important omega-3/omega-6 fatty ratio off balance.

References

Lynne H. Shinto et al. White Matter Lesions and Neuronal Integrity Breakdown in Older Adults. A Randomized Clinical trial. JAMA network Open. 2023

Aleix Sala-Vila et al. Red Blood Cell DHA Is Inversely Associated with Risk of Incident Alzheimer’s Disease and All-Cause Dementia: Framingham Offspring Study.  Nutrients. 2022