American researchers followed the diet and health of nearly 40,000 adults over 65 years of age for over 15 years. The bottom line? People who ate eggs regularly developed Alzheimer's disease less often than those who avoided this food.
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A new study published in The Journal of Nutrition shows that people who ate at least five eggs a week had up to a 27% lower risk of developing Alzheimer's disease compared to those who ate almost no eggs.
The study was conducted by researchers from the Loma Linda University School of Public Health and analyzed the data of about 40,000 American adults over the age of 65. The participants were monitored for an average of 15.3 years, and the researchers analyzed both their diet and any subsequent Alzheimer's cases.
At the start of the study, each participant completed detailed dietary questionnaires. The researchers took into account both eggs consumed directly – boiled, fried or in the form of an omelette – as well as those included in other food products. Alzheimer's cases were later identified by matching dietary data with medical records and the US Medicare system.
Nutrients in eggs, allies of the brain
“The main finding is that moderate egg consumption was associated with a lower incidence of Alzheimer's disease in this cohort,” says Jisoo Oh, associate professor of epidemiology at Loma Linda University, quoted by Psy Post. “However, this does not mean that eggs prevent Alzheimer's, but that they may represent a component of a diet beneficial for brain health.”
Also, experts say that eggs contain several important nutrients for brain function: choline, essential for memory and communication between nerve cells; lutein and zeaxanthin – two antioxidants associated with better cognitive performance; but also omega-3 fatty acids, important for the structure of brain cells. Professor Joan Sabaté, the main coordinator of the research, explains that the egg yolk is rich in phospholipids, essential substances for the transmission of nerve signals in the brain.
Even a few eggs a week are beneficial
According to the study, people who ate eggs less often also appeared to have a lower risk of Alzheimer's. More specifically, the researchers observed that those who consumed eggs one to three times a month had a 17% lower risk, and people who consumed eggs two to four times a week had a 20% reduced risk.
The biggest difference was seen in participants who consumed at least five eggs per week: the risk of Alzheimer's was up to 27% lower compared to people who almost completely avoided this food. The authors say one of the most surprising findings was that people who ate no eggs at all appeared to have a higher risk than those who ate even small amounts.
“Compared to those who don't eat eggs at all, eating at least five eggs a week can seriously reduce the risk of Alzheimer's,” said Joan Sabaté, a professor at Loma Linda University School of Public Health and the study's principal investigator.
Limitations and Precautions
The authors point out, however, that the study is observational, which means it cannot directly prove that eggs prevent Alzheimer's disease. “We cannot establish a causal relationship”warns Jisoo Oh.
They say they tried to eliminate the influence of other factors that can affect brain health, such as age, education level, physical activity, sleep, hypertension, diabetes or cardiovascular disease. However, there is a possibility that other lifestyle habits of the participants may have influenced the results.
They also point out that the people included in the study were part of a group known for a healthier lifestyle than the average population – many rarely smoked and consumed little alcohol. “Alzheimer's disease develops slowly over several decades, which is why researchers are trying to identify dietary habits that could influence the risk of developing the disease,” says Jisoo Oh.
The research team says the next step is to look in more detail at the biological mechanisms by which nutrients in eggs might influence brain health, particularly the role of choline and DHA – a type of omega-3 fatty acid associated with nervous system function.
