Eating eggs almost daily could slash dementia risk by 27%, according to a major study that tracked nearly 40,000 older adults for 15 years. Researchers found that consuming one egg at least five days a week was linked to a significantly lower chance of developing Alzheimer’s disease compared with never eating eggs. Even smaller amounts appeared to offer protection: eating eggs just one to three times a month was associated with a 17% reduction in risk, while two to four eggs a week cut the risk by 20%.
The study
The research, published in the Journal of Nutrition under the title “Egg intake and the incidence of Alzheimer’s disease in the Adventist Health Study-2 cohort linked with Medicare data,” analysed data from a large prospective cohort of Seventh-day Adventists in the United States and Canada. The Adventist Health Study-2 (AHS-2) began in 2002 with the aim of recruiting 100,000 participants to investigate the role of diet and lifestyle in cancer, chronic diseases and longevity. Participants completed extensive questionnaires on diet and lifestyle. Over the 15-year follow-up period, 2,858 of the 39,498 adults aged over 65 were diagnosed with Alzheimer’s disease.
Seventh-day Adventists are known for promoting a healthy lifestyle, often following vegetarian or vegan diets and avoiding smoking and alcohol. The study’s lead author, Jisoo Oh, an associate professor of epidemiology at Loma Linda University School of Public Health, acknowledged that “Seventh-day Adventists do eat a healthier diet than the general public” and stressed that the findings should be seen in the context of overall health. “Research supports eggs as part of a healthy diet,” she added. The observational study was peer-reviewed and partly funded by the American Egg Board, an organisation created in 1976 to promote the U.S. egg industry. The American Egg Board states that its research grants are administered through a competitive process with proposals reviewed by external nutrition science experts, and that it follows integrity guidelines to minimise potential bias. However, a systematic review of industry-funded research on cholesterol noted that conclusions in such studies may be influenced by the funding source.
The nutrients behind the benefit
While no diet can cure or reverse dementia, a healthy, balanced diet can reduce risk factors such as high blood pressure and cholesterol that are linked to the condition. Eggs, however, contain several specific nutrients that scientists believe directly support brain health.
Joan Sabaté, a professor at Loma Linda University School of Public Health who conducted the study, explained that eggs are a significant source of choline, a nutrient that acts as a precursor to acetylcholine – a chemical messenger critical for memory and learning. Choline is also essential for forming and repairing cell membranes, particularly in the brain. Higher dietary choline intake has been associated with better cognitive function and memory, and some research suggests that choline supplementation can improve symptoms in brain-related diseases including Alzheimer’s. Interestingly, one study indicated that only a medium level of choline intake was protective for cognitive function, with no statistical significance at the highest level, suggesting that more is not necessarily better.
Eggs also contain the carotenoids lutein and zeaxanthin – yellow and orange pigments found in foods such as spinach and sweetcorn. These compounds accumulate in brain tissue and are associated with improved cognitive performance and reduced oxidative stress. Studies have linked higher consumption of lutein- and zeaxanthin-rich foods to better cognitive function and a lower risk of dementia, and they may also play an anti-inflammatory role in the brain.
Omega-3 fatty acids, another key component of eggs, are important for brain health. These fats are central to the structure of brain cell membranes, supporting neuron communication and reducing inflammation. Low omega-3 levels have been linked to cognitive decline and an increased risk of dementia. The omega-3s in eggs are thought to help reduce both inflammation and oxidative stress in the brain – two processes that are increasingly suspected of contributing to the development of Alzheimer’s disease.
The bigger picture: inflammation, oxidative stress and cholesterol
Chronic inflammation in the brain is now considered a key risk factor for Alzheimer’s. Systemic inflammation can promote a proinflammatory environment in the central nervous system, potentially worsening the amyloid plaques and tau tangles that characterise the disease. Similarly, oxidative stress – an imbalance between free radicals and antioxidants – is particularly damaging to the brain because of its high oxygen consumption and lipid content. Oxidative stress can damage brain cells and contribute to the accumulation of beta-amyloid plaques. Nutrients such as lutein and zeaxanthin possess antioxidant properties that may help counter this damage.
High levels of LDL (“bad”) cholesterol in midlife have also been associated with an increased risk of dementia, although the exact mechanism is not fully understood because the brain produces its own cholesterol. Some research suggests that genetically high cholesterol levels do not confer an increased risk for Alzheimer’s, and the link between dietary cholesterol and brain health remains a complex area of study.
Context and limitations
There are currently an estimated 982,000 people with dementia in the UK, and Alzheimer’s disease is the most common cause. In 2019, dementia and Alzheimer’s accounted for 12.5% of all registered deaths in England and Wales. By 2024, dementia had become the leading cause of death in the UK, responsible for over 76,000 deaths (11.9% of all deaths) and the leading cause of death for women. The number of deaths due to dementia is projected to quadruple by 2040.
The findings from the Adventist Health Study-2 add to a growing body of research on egg consumption and cognitive function. A systematic review of studies found that moderate egg intake – around half to one egg per day – may be associated with a reduced risk of dementia and better memory performance, although results were inconsistent and one study linked high intake (more than one egg per day) to an increased risk. Another study indicated that greater egg consumption in older adults was not associated with cognitive impairment, and men who consumed more eggs performed better on memory tests, though no such association was found in women.
“We want people to focus on overall health along with this knowledge about the benefit of eggs,” said lead author Jisoo Oh, urging caution against viewing eggs as a standalone solution.