For years, eggs were considered a controversial food, mainly due to their cholesterol content. Now, a new study from the United States points to a possible link between egg consumption and a lower risk of being diagnosed with Alzheimer’s in older age. The findings arouse great interest, but also require caution: The researchers did not prove a causal relationship, and the egg alone will not become a cure for dementia.
The study, conducted at Loma Linda University in California and published in the scientific journal The Journal of Nutrition, examined the link between dietary habits and the onset of Alzheimer’s among adults aged 65 and older. The researchers analyzed data from 39,498 participants from the Adventist Health Study, a large American cohort studied over years, and linked the data to records from Medicare, the American health insurance system for older adults.
The follow–up lasted an average of 15.3 years. During this period, 2,858 of the participants were diagnosed with Alzheimer’s. The researchers examined the frequency of egg consumption using dietary questionnaires, and divided the participants according to consumption levels: Those who did not eat eggs or ate them rarely; those who ate eggs one to three times a month; once a week; two to four times a week; and five times a week or more.
The main result aroused interest: Compared to those who did not eat eggs or ate them rarely, those who ate eggs one to three times a month or once a week had a 17% lower risk of an Alzheimer’s diagnosis. Those who ate eggs two to four times a week had a 20% lower risk. In the group that ate eggs five times a week or more, a decrease of up to 27% in risk was recorded.
The researchers examined not only overtly consumed eggs, such as a hard–boiled egg, an omelet, a sunny–side up egg, or scrambled eggs, but also eggs that appear inside baked goods and prepared foods. However, the primary scientific interest is related to the whole egg, and especially to the yolk, where a large portion of the nutritional components considered relevant to brain health are concentrated.
The possible biological explanation lies in the nutritional composition of the egg. Eggs contain choline, a substance used by the body to produce acetylcholine, a neurotransmitter associated with memory, learning, and cognitive function. They also contain vitamin B12, lutein, zeaxanthin, high–quality protein, and small amounts of omega–3 fatty acids. Some of these components have been studied in the past in the context of brain health, reducing oxidative stress, and nerve cell function.
The researchers note that the findings remained significant even after adjustments for demographic factors, lifestyle habits, underlying diseases, and general dietary patterns. In other words, the link did not disappear even when they tried to account for variables such as health status, lifestyle, and the quality of the overall diet. Despite this, a study of this type cannot prove that eggs are the cause of the risk reduction.
People who eat eggs regularly may differ from people who do not eat eggs in other ways as well: They may eat a more balanced diet, engage more in physical activity, turn more to preventive medicine, or lead a healthier lifestyle. The researchers attempted to statistically correct for some of these differences, but in an observational study, there always remains a possibility of influence from unmeasured factors.
There is also an additional limitation: The study population included many members of the Adventist community, which is considered relatively healthy compared to the general population in the United States. Many of them adhere to a structured diet, avoidance of smoking, and a healthier lifestyle. Therefore, it is not clear whether the findings can be fully projected onto the general public, for example, onto those whose diet includes a lot of processed food, saturated fat, processed meat, and salt.
The method of preparing the eggs is also important. A hard–boiled egg or an omelet with vegetables is not nutritionally similar to eggs regularly served alongside sausages, high–fat cheeses, butter, savory pastries, or fried food. The researchers themselves emphasize that the message is not “to eat eggs without limitation,” but rather to view them as part of a balanced diet that includes vegetables, fruits, legumes, whole grains, nuts, fish, and high–quality oils.
The study also has an aspect that requires transparency: Part of the funding was provided by the American Egg Board, a body that represents the egg industry in the United States. According to the reports, the researchers noted that the funding body was not involved in the design of the study, the analysis of the data, or the interpretation of the findings. However, when it comes to nutrition research on commercial food, such funding must appear clearly and be taken into account when reading the findings.
Nutrition and neurology experts who commented on the study in the United States emphasized that these are encouraging findings, but not a new medical recommendation. Eggs may fit into a healthy menu for most older adults, especially when they are prepared simply and combined with high–quality foods. On the other hand, patients with underlying diseases, blood lipid disorders, unbalanced diabetes, or significant heart disease should consult their physician or dietitian before making a permanent dietary change.
Alzheimer’s is a degenerative disease of the brain, characterized by a gradual decline in memory, language, orientation, daily functioning, and later also behavioral changes. To date, no proven dietary way has been found to prevent it completely, but evidence is accumulating that a healthy lifestyle may reduce risk or delay cognitive decline. Physical activity, maintaining normal blood pressure, balancing diabetes, avoiding smoking, sufficient sleep, social connections, and a Mediterranean diet are all considered part of the broad picture.
Source:
www.jpost.com
