A major recent analysis published in the prestigious Journal of the American Medical Association confirms that regular consumption of fish and seafood is associated with a reduced risk of Alzheimer’s.

  1. Diet, a major lever for prevention
  2. Fish and seafood lower the risk of dementia
  3. Net neurological benefit despite traces of mercury
  4. Avoid swordfish, prefer

It is estimated that globally, the number of patients affected by neurodegenerative diseases such as Alzheimer’s disease will triple over the next few years, from 50 million people to approximately 130 million in 2050. there are still no drugs capable of blocking this neuro-degeneration, the only way to avoid this Alzheimer’s “tsunami” is to prevent the development of the disease or at the very least significantly delay its progression.

The good news is that several studies have shown that this preventive approach is easy to apply. A good example is the strong association that exists between dietary habits and the risk of being affected by Alzheimer’s disease, particularly with regard to the Mediterranean diet.

Studies show that followers of this diet, whose diet is rich in olive oil, fruits, vegetables, legumes and whole grain cereals and where animal protein comes mainly from poultry and fish, but not from meats red, are less at risk of developing the disease.

The contribution of fish to this protective effect seems important, since several studies have observed an improvement in cognitive functions and a reduced risk of dementia in people who regularly consume fish and seafood.

These foods are exceptional sources of docosahexaenoic acid (DHA), a long-chain omega-3 fatty acid very important for the brain. By integrating into the membrane of neurons, DHA facilitates the transmission of nerve impulses at the synapses and thus allows optimal functioning of these neurons, thereby reducing the risk of cognitive decline.

Despite this positive effect of DHA of marine origin, many people still wonder about the long-term impact of regular consumption of fish and seafood. Some of these aquatic species indeed contain traces of methyl-mercury, a neurotoxic contaminant known to interfere with neuronal development.

Although present in minute quantities, this form of mercury is not eliminated from the body and could therefore accumulate over the years in regular fish consumers. In other words, could the presence of mercury in marine species counteract the protective effect of fish and seafood on cognitive function?

To answer this question, a team of American scientists examined the autopsied brains of 286 people who participated in the “Rush Memory and Aging Project (MAP)”, a clinical study that assesses the cognitive health of elderly people who have lived in the region. from Chicago.

They first determined by microscopic examination the presence of pathological signs of dementia in the different brains, both for Azheimer’s disease (amyloid plaques) and dementia in general (Lewy bodies). In parallel, the mercury content of these brain samples was measured using an ultrasensitive technique (neutron activation analysis).

Finally, the relationship between these data and fish consumption was determined by examining the dietary habits of the people in the study, which had been defined before their death through annual questionnaires.

The results are very encouraging, both for the beneficial effects of fish and for the safety aspect associated with its consumption. The researchers observed that the consumption of a meal of fish per week is indeed associated with a greater quantity of mercury in the brain, but that this presence of mercury has no impact on the risk of dementia.

On the contrary, they observed that the regular consumption of fish was associated with a marked decrease in the pathological signs of Alzheimer’s disease, confirming at the same time the positive impact of fish consumption on cognitive functions.

Over the past few years, the importance of reducing the consumption of red meats has been regularly emphasized, whether to reduce the risk of colorectal cancer or cardiovascular disease. Fish is undoubtedly one of the most interesting alternatives, both for its nutritional profile and for its protective effects against several chronic diseases.

The fish that contain the most mercury, ie swordfish or shark, are species that are not very popular with us and therefore very easy to avoid. This precaution is particularly important for pregnant women because of the very harmful effect of mercury on the fetus.

Conversely, salmon, sardines or even Atlantic mackerel, all fish with an exceptional omega-3 fat content, contain only traces of mercury and can be eaten regularly in order to take advantage of their multiple positive effects on health, both physical and mental.


The World Alzheimer Report 2015. The Global Impact of Dementia: An analysis of prevalence, incidence, cost and trends updates.

Tangney CC et al. Adherence to a Mediterranean-type dietary pattern and cognitive decline in a community population. Am J Clin Nutr; 93: 601-607. 3. Morris MC et al.

Association of seafood consumption, brain mercury level, and APOE – 4 status with brain neuropathology in older adults. JAMA 2016; 315: 489-97.

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