A large observational study highlights an unexpected association: adults over 65 who regularly eat eggs have a reduced risk of Alzheimer's disease.
Over more than fifteen years, scientists followed over 40,000 people and found that eating at least five eggs per week reduced the risk by 27% compared to no consumption. This association persisted after adjusting for many other dietary factors.
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This research, conducted by Loma Linda University, used health data from people aged 65 and older. Scientists cross-referenced dietary reports with medical diagnoses from Medicare. Even moderate consumption, of one to three eggs per month, was associated with a 17% protection. The results were published in the
Journal of Nutrition. The study is part of the large Adventist Health Study 2, which examines links between lifestyle and chronic diseases.
Eggs are rich in beneficial compounds for the brain. Choline, for example, helps produce substances essential for memory and communication between neurons. Lutein and zeaxanthin, antioxidants, accumulate in brain tissues and reduce oxidative stress. Not to mention omega-3 fatty acids, present in good amounts. The phospholipids in egg yolks, which represent nearly 30% of lipids, also play a role in neurotransmitter receptor function.
The lead author, Jisoo Oh, noted that participants, drawn from the Adventist community, already had an overall healthy diet. This population consumes less meat and more fruits, vegetables, and whole grains than average. The results therefore indicate that eggs can provide an additional benefit within an already favorable diet.
Researchers followed participants for an average of 15.3 years. Alzheimer's diagnoses came from Medicare data. The study was partly funded by the American Egg Board, but its conclusions are consistent with other work on nutrition and the brain. The authors note that additional studies are needed to confirm the cause-and-effect relationship.
Choline: a key nutrient for the brain
Choline is a substance often classified among the B vitamins. It plays a role in the production of acetylcholine, a neurotransmitter essential for memory and learning. Without sufficient intake, cognitive functions may decline.
Eggs are among the best dietary sources of choline. A single egg yolk provides about 150 mg, or a quarter of the recommended daily intake. Other foods like liver, fish, or legumes also contain it, but in smaller amounts.
A choline deficiency can affect cell membrane structure and nerve signaling.
Lutein and zeaxanthin: antioxidants for the brain
Lutein and zeaxanthin are plant pigments from the carotenoid family. They are found in green vegetables like spinach and kale, but also in egg yolks. Their particularity is that they accumulate in the macula of the eye and in certain areas of the brain.
In the brain, these compounds protect neurons from oxidative stress and inflammation. They improve cell membrane fluidity and communication between synapses. Several studies have linked high levels of lutein to better cognitive performance in seniors.
Eggs offer a particularly bioavailable source of these carotenoids. Cooking does not alter their effectiveness. Eating eggs regularly helps maintain good levels of lutein and zeaxanthin, potentially beneficial for preventing age-related decline.