Older adults who consumed at least one egg per week had a significantly lower risk of developing Alzheimer’s dementia and showed less Alzheimer’s disease pathology in the brain, according to a cohort study of more than 1,000 participants.
The analysis included 1,024 patients from the Rush Memory and Aging Project. Participants had a mean age of 81.4 years and were predominantly female (74.8%). All were dementia-free at baseline and completed a food frequency questionnaire to assess dietary intake, including egg consumption.
In multivariate-adjusted model, consumption of 1 egg per week in the 6.7-year follow-up was associated with a hazard ratio (HR) of 0.53, and at least 2 eggs per week yielded an HR of 0.53, both compared with consumption of less than 1 egg per month. "We found that consuming at least 1 egg/wk was associated with a 47% reduced risk of Alzheimer’s dementia," the authors wrote, led by Yongyi Pan, MPH, of the Friedman School of Nutrition Science and Policy at Tufts University, Medford, Mass. The models adjusted for age, sex, education, body mass index, smoking status, ApoE-ε4 genotype, physical activity, cognitive activity, vascular risk factors, and dietary intakes of leafy greens, strawberries, seafood, and total energy.
To assess whether the relationship extended to brain pathology, the researchers examined autopsy results from 578 deceased participants. In this subgroup, consuming 1 egg per week was associated with an HR of 0.51 for Alzheimer’s pathology. Those who consumed at least 2 eggs per week had an HR of 0.62.
The researchers also examined dietary choline as a mediator because it is found abundantly in eggs and plays a role in brain function. Mediation analysis showed that 39.2% of the association between egg intake and reduced Alzheimer’s dementia risk was explained by dietary choline.
Participants who consumed at least 2 eggs per week had an excess relative risk of 0.34 for longer dementia-free survival compared with those who consumed less than 1 egg per month. Mean dietary choline intake increased across egg consumption levels, from 238.9 mg/d in the lowest group to 337.8 mg/d in the highest. Total energy intake also increased from 1474.9 kcal/d to 1869.9 kcal/d. These dietary variables were controlled in the statistical models.
"Analysis showed that 39% of the total effect of egg intake on incident Alzheimer’s dementia was mediated through dietary choline," Pan and colleagues wrote.
While causality cannot be inferred, consistent findings across clinical diagnoses, postmortem brain pathology, and choline mediation analysis suggest a potential protective association between egg consumption and Alzheimer’s dementia.
The study used validated dietary assessments, annual clinical evaluations, and neuropathological confirmation of Alzheimer's disease, which provided a robust data set. Limitations included reliance on baseline diet and self-reported intake.
Full disclosures can be found in the published study.
Source: The Journal of Nutrition