Alzheimer’s is an insidious disease and the leading cause of dementia. It’s also one of the major causes of death in old age. Diet plays a major role in preventing the disease. In fact, having high concentrations of the omega-3 fatty acid, DHA, in the blood can halve the risk of developing Alzheimer’s disease, according to a study that is published in Nutrients. DHA (docosahexaenoic acid) is found in oily fish and fish oil supplements. This essential fatty acid is also found in all our cell membranes (including nerve cells) and plays a key role in maintaining our general health and cognitive skills. Unfortunately, modern diets contain far too little omega-3, but science is not quite sure how much we need.
Alzheimer’s disease progresses gradually over a period of many years and leads to impairment of our memory, concentration, lingual skills, and orientation. Alzheimer’s disease is the leading cause of dementia, and it even changes a person’s personality. During the development of the condition, proteins such as beta-amyloid and tau accumulate This results in local inflammation and causes the neurons in several parts of the brain to perish. Scientists have also observed insulin resistance in the brain, which is why Alzheimer’s disease is often referred to as type 3 diabetes. Most Alzheimer’s patients die within a period of 7-10 years. Genes, diet, lifestyle, and ageing processes play a major role in the development of the disease and in other types of dementia. It even appears that a deficiency of the omega-3 fatty acid DHA (docosahexaenoic acid) also plays a determining role.
- In 2015, there were 48 million people with Alzheimer’s disease worldwide. The number is on the rise
- Alzheimer’s disease is the seventh most common cause of death in the United States
- Lack of omega-3 and other nutrients increases the risk of developing the disease
Omega-3 fatty acids and their role in brain health
Omega-3 fatty acids are polyunsaturated fatty acids that occur in different forms in nature. Humans are particularly dependent on EPA and DHA because both fatty acids are an integral part of our cell membranes where they handle a host of different physiological functions. The brain contains particularly large amounts of DHA, which is important for the neuronal synapses that are responsible for exchanging information between the neurons. EPA and DHA also increase the cerebral blood flow, thereby supporting our ability to solve cognitively challenging tasks. The omega-3 fatty acids also protect against chronic inflammation that can damage the brain.
High blood levels of DHA can cut the risk in half
There is increasing focus on the omega-3 fatty acids and their role in brain health and the consequences of getting too little of these fatty acids from the diet. The new study was headed by PhD Aleix Sala-Vila, who assumed that a higher dietary intake of omega-3 would be able to lower the risk of developing Alzheimer’s disease, especially in people who are genetically predisposed to the disease. The study was carried out as an observational study and was part of a larger population study known as the Framingham Offspring Cohort and, which has been ongoing for several generations. The new study includes 1,490 participants aged 65 years. None of the participants had dementia at baseline. The team of scientists compared the concentration of DHA in the red blood cells of the participants with their risk of developing Alzheimer’s disease later on. They also tested interactions with the APOE-e4 gene, which normally doubles the risk of developing Alzheimer’s disease.
They found that the quintile of participants with the highest levels of DHA in their blood were 49 percent less likely to develop Alzheimer’s disease compared with the quintile that had the least DHA in the blood. In addition, the scientists noted that people with the APOE-e4 gene benefited the most from having high levels of DHA in their blood.
Based on these results, the scientists conclude that increased intake of omega-3 fatty acids from the diet or from supplements can help prevent Alzheimer’s disease and delay the progression in cases where the disease has already started. These are simple and inexpensive measures that have the potential to improve quality of life and prolong life for millions of people around the globe. The new study is published in Nutrients and supports earlier research.
Alarming need for more omega-3
Modern diets contain substantially less omega-3 than earlier. This is because we eat less oily fish such as herring, salmon, and mackerel. In addition, livestock and farmed fish get unnatural fodder with less omega-3 and more omega-6, and this affects the nutritional value of meat, dairy products, eggs, and farmed fish like salmon.
The official dietary guidelines suggest eating fish several times per week and making sure that at least 200 grams come from oily fish that are particularly rich in the omega-3 fatty acids, EPA and DHA. A serving of herring or salmon daily is normally enough. If you don’t like fish or simply don’t eat enough seafood, a high-quality fish oil supplement is a good investment.
Content of pure omega-3
- One serving of herring: 1-2 grams
- A steak of free-range salmon: 3-4 grams
- A large fish oil capsule: 1 gram
- A small fish oil capsule: 500 mg
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
R. Power et al. “Omega-3 fatty acid, carotenoid and vitamin E supplementation working memory in older adults: A randomized clinical trial. Clinical Nutrition, 2021.
James J. Dicolantonio and James H. O´Keefe. The Importance of Marine Omega-3s for Brain Development and the Prevention and Treatment of Behavior, Mood, and Other Brain Disorders. Nutrients. 2020
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