A new study published in The Journal of Nutrition provides evidence that eating eggs in moderation tends to reduce the risk of being diagnosed with Alzheimer’s disease in older adults. Egg consumption is associated with a lower risk of cognitive decline in people over 65 years of age. These findings suggest that incorporating eggs into a balanced diet may have protective effects on brain health in the long term.
Alzheimer’s disease is a progressive brain disorder that slowly destroys memory and thinking skills. With no established cure, medical professionals are increasingly focusing on preventing the disease before it develops. Researchers wanted to investigate how daily lifestyle choices affect brain health as we age.
“The study was motivated by the growing need to identify modifiable dietary factors that may influence Alzheimer’s disease risk, especially given the lack of a curative treatment,” said Jisoo Oh, associate professor of epidemiology at Loma Linda University School of Public Health. “Eggs are widely consumed and contain nutrients related to brain health, but there is relatively limited evidence linking egg consumption to clinically diagnosed Alzheimer’s disease over long-term follow-up periods. The Adventist Health Study-2 provided a unique opportunity to examine this question in a large cohort with detailed dietary data and linkage to Medicare records.”
Previous research suggests that certain nutrients in eggs may support brain function. Eggs are known to be a source of important nutrients that support brain health, said Joan Sabate, a professor at Loma Linda University’s School of Public Health and the study’s principal investigator. They provide choline, a nutrient that helps nerve cells communicate and form memories.
Eggs also contain certain carotenoids, such as lutein and zeaxanthin, which accumulate in brain tissue and are associated with improved cognitive performance and reduced oxidative stress. Additionally, eggs provide important omega-3 fatty acids that help maintain the physical structure of brain cells. Egg yolks are particularly rich in phospholipids, which make up nearly 30% of the egg’s total lipids and are essential for proper brain signaling.
To track these dietary factors, researchers analyzed data from an ongoing project called the Adventist Health Study-2. The scientists focused on about 40,000 U.S.-based subjects who were at least 65 years old. Eligibility was determined using the Medicare Master Beneficiary Summary File. Participants were monitored for an average of 15.3 years.
At the beginning of the project, each person completed an extensive dietary questionnaire. Researchers studied egg consumption in visible forms, including scrambled, fried, and boiled eggs. We also measured hidden methods such as eggs in baked goods and packaged foods.
To track who developed Alzheimer’s disease over time, researchers linked dietary surveys to official Medicare health insurance claims. By using billing codes from hospital visits and doctor’s appointments, scientists were able to pinpoint when participants received formal medical diagnoses. According to these Medicare records, cases of Alzheimer’s disease in the Adventist Health Study-2 cohort were diagnosed by a physician.
The researchers adjusted their statistical model to account for a wide range of factors that can influence brain health. These variables include age, gender, race, education, physical activity level, and sleep habits. We also took into account whether participants had other medical conditions such as high blood pressure, diabetes, or heart disease.
Because overall diet plays a huge role in health, the researchers controlled intake of other major food groups. To be as precise as possible, the scientists also performed separate analyzes to see what happened when they hypothetically replaced eggs with other protein sources such as nuts, seeds, and legumes.
Scientists found that people who ate eggs had a significantly lower risk of developing the condition than those who never or rarely ate eggs. This inverse relationship remained consistent even after adjusting for all demographic, lifestyle, and medical variables.
“The main takeaway is that in this cohort, moderate egg intake was associated with a lower risk of Alzheimer’s disease,” Oh told SciPost. “People who regularly consumed eggs had a lower risk than those who rarely or never ate eggs. However, this does not mean eggs protect against Alzheimer’s disease, but rather that eggs may be one component of a brain-healthy dietary pattern.”
The specific risk reduction varied depending on how often participants consumed eggs. “Eating at least five eggs a week can reduce your risk of Alzheimer’s disease compared to not eating eggs at all,” Sabate says. Eating one egg a day for at least five days a week can reduce your risk of Alzheimer’s disease by up to 27 percent.
Even reducing the frequency of egg consumption significantly reduced the risk of Alzheimer’s disease. Researchers found that eating eggs one to three times a month reduced the risk by 17%, and eating eggs two to four times a week reduced the risk by 20%, Sabate said.
The authors also used statistical tools to map the precise relationship between the weight of eggs consumed each day and disease risk. This ongoing analysis showed that eating zero eggs per day was associated with a higher risk of Alzheimer’s disease compared to eating 10 grams of eggs per week, which is roughly equivalent to one large egg.
“One notable finding was the consistent inverse association across multiple levels of adjustment, even after accounting for overall diet, lifestyle, and comorbidities,” Oh said. “We were also interested in observing that even relatively modest intakes (e.g., 1 to 3 times per month) were associated with decreased risk. The nonlinear pattern in which zero intake was associated with increased risk was also an unexpected and interesting observation.”
The researchers acknowledge that their study has some limitations. One potential problem is that dietary habits were only recorded at the beginning of the long follow-up period. Some people may have changed their eating habits during the 15 years of monitoring.
“This is an observational study, so we can’t prove cause and effect,” Oh said. “Although we adjusted for a number of confounders, residual confounding is always possible and dietary intake was only measured at baseline. It is also important not to interpret this result as if eggs were the sole prevention strategy, or that higher intake necessarily yields a greater effect.”
The population studied also provides a specific context for the findings. The participants belonged to a group known for being health conscious.
“One important context is that this was a health-conscious cohort with relatively low rates of smoking and alcohol use, which strengthens internal validity but may limit generalizability,” Oh said. “Additionally, Alzheimer’s disease develops over decades, so identifying long-term dietary associations is especially important. Overall, the findings add to the growing body of evidence suggesting that whole foods rich in brain-related nutrients, such as eggs, may play a role in healthy cognitive aging.”
Looking forward, the authors plan to extend these findings to better understand the mechanisms at play.
“Future studies should investigate whether these associations apply to a more diverse population and whether dietary patterns early in life influence the risk of Alzheimer’s disease later in life,” Dr. Oh said. “We are also interested in exploring the role of specific egg-derived nutrients such as choline and DHA and their biological pathways. Ultimately, integrating biomarker and mechanistic studies will help strengthen causal inferences.”
The study, “Egg Intake and Alzheimer’s Disease Incidence in Adventist Health Study-2 Cohort Linked with Medicare Data,” was authored by Jisoo Oh, Keiji Ohda, Gabriela Chiriac, Gary E Fraser, Rawiwan Sirirat, and Joan Sabate.
The authors issued the following statement regarding conflicts of interest and funding: “Initial support for the cohort was provided by the National Cancer Institute (grant 1U01CA152939). Analysis of this study was supported by an investigator-initiated grant from the American Egg Board. The funding sources had no role in study design, conduct, data analysis, interpretation, manuscript preparation, or publication.”
