A new study published in The Journal of Nutrition has found that regular egg consumption may be linked to a lower risk of developing Alzheimer’s disease - a progressive condition that affects memory, thinking, and daily functioning. The research draws on data from the long-running Adventist Health Study-2, analysing dietary habits and health outcomes among 39,498 participants over an average follow-up period of 15.3 years, during which 2,858 individuals developed Alzheimer’s disease.
The findings suggest a consistent association between egg consumption and reduced risk. Compared to individuals who never or rarely consumed eggs, those who ate eggs even a few times a month showed a lower likelihood of developing Alzheimer’s. The benefit appeared to increase with frequency, with people consuming eggs five or more times a week showing the lowest risk among all groups studied. Even after adjusting for demographic factors, lifestyle behaviours, comorbidities, and intake of other food groups, the inverse relationship remained significant. The study further noted that “zero egg intake was curvilinearly associated with significantly elevated Alzheimer’s disease risk,” indicating that even modest inclusion of eggs in the diet may be beneficial.
Considering that, as the World Health Organisation notes, “In 2021, 57 million people had dementia worldwide, over 60% of whom live in low-and middle-income countries. Every year, there are nearly 10 million new cases. Dementia results from a variety of diseases and injuries that affect the brain. Alzheimer disease is the most common form of dementia and may contribute to 60–70% of cases,” this study could add to the growing conversation around diet as a modifiable risk factor in preventing cognitive decline, particularly in rapidly ageing populations.
What makes eggs a potential brain-protective food?
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Alzheimer’s disease is “a progressive neurodegenerative disorder characterised by the accumulation of amyloid-β plaques, neurofibrillary tangles, and widespread neuronal loss, ultimately leading to cognitive decline, loss of independence, and death.” With no definitive cure and limited effectiveness of current treatments, the focus has increasingly shifted towards prevention. As the study highlights, “in the absence of curative treatments and given the limited efficacy of current pharmacological therapies, prevention strategies targeting modifiable risk factors have become increasingly important.”
Diet plays a crucial role in this context, and eggs have emerged as a potentially beneficial food due to their nutrient density. They are rich in choline, a precursor to acetylcholine, which is essential for memory and cognitive function. Eggs also contain lutein and zeaxanthin, carotenoids known to accumulate in brain tissue and support cognitive performance by reducing oxidative stress. The study notes that “these nutrients may act synergistically to support cognitive resilience and mitigate neurodegenerative processes,” suggesting that their combined effect may be more significant than any single nutrient alone.
In addition, eggs provide high-quality protein, including tryptophan, which is involved in mood regulation and cognitive processes, along with docosahexaenoic acid (DHA), an omega-3 fatty acid critical for neuronal health, synaptic plasticity, and brain development. Vitamin B12, another key nutrient found in eggs, plays an important role in maintaining brain function. Deficiency in B12 has been linked to increased homocysteine levels, a recognised risk factor for Alzheimer’s disease, and may contribute to neuroinflammation and cognitive decline. The study further notes that deficiencies in choline and DHA have been documented in individuals with Alzheimer’s, strengthening the biological plausibility of the observed association.
How strong is the evidence?
While the findings are significant, they also build on a growing body of research examining the relationship between egg consumption and cognitive health. The study states that “emerging evidence suggests a potential role for egg consumption in modifying Alzheimer’s disease risk,” although earlier research has often been limited by short follow-up periods or reliance on self-reported cognitive outcomes.
The Adventist Health Study-2 provides a stronger basis for analysis due to its large sample size, long follow-up duration, and use of clinically confirmed Alzheimer’s diagnoses through Medicare data. This allows for a more robust assessment of long-term associations between diet and disease risk.
Supporting evidence from other studies further strengthens the findings. A Finnish prospective study that followed middle-aged men for over two decades found that moderate egg consumption was associated with better neuropsychological performance without increasing Alzheimer’s risk. Similarly, research from Spain’s EPIC cohort observed that higher whole egg intake was linked to lower dementia risk. In the United States, data from the Rush Memory and Ageing Project indicated that consuming at least one egg per week was associated with a 46% reduced risk of Alzheimer’s disease.
At the same time, the study acknowledges variability in existing research. “Inconsistent adjustment for comorbidities and socioeconomic factors also introduces potential confounding,” the authors note, highlighting the complexity of isolating the impact of a single dietary component. Interestingly, previous findings from the same cohort indicated that while vegetarian diets were associated with reduced overall mortality, vegetarians showed higher cause-specific mortality from dementia, suggesting that specific nutrient intake rather than overall diet type may play a crucial role in brain health.
Limitations of the study
Despite its strengths, the study outlines several limitations that must be considered. Although it uses a prospective design, it remains observational in nature, meaning it cannot definitively establish cause and effect. As the researchers state, “residual confounding cannot be entirely ruled out in observational studies of this nature,” and unmeasured variables may still influence the results.
Dietary intake was assessed only at baseline, which introduces potential uncertainty. “It is possible that dietary changes occurred during the preclinical phase of Alzheimer’s disease… potentially leading to reverse causation.” However, the study also notes that dietary patterns within this cohort tend to remain relatively stable over time, particularly among older adults, which may reduce this concern.
Another limitation relates to disease identification. Alzheimer’s cases were identified using Medicare claims data, which, while generally reliable, may not capture all cases, particularly those with milder symptoms. The researchers acknowledge that “Medicare claims data may underestimate the identification of individuals with Alzheimer’s disease.”
The study also highlights methodological challenges in analysing disease risk in older populations. “Because death is a terminal event that may be related to the non-terminal event of Alzheimer’s diagnosis… treating death as non-informative censoring can constrain the interpretation of the hazard ratios,” meaning the results should be interpreted with caution in terms of absolute risk.
Additionally, although the highest category of egg consumption showed the greatest reduction in risk, relatively few participants consumed eggs daily, limiting the ability to assess the effects of higher intake levels. Despite adjusting for multiple variables, the authors reiterate that “residual confounding cannot be entirely ruled out,” underlining the need for further research in more diverse populations and real-world settings.
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS
