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Eggs make a regular appearance on many of our plates, from breakfast all the way to dinner. They’re versatile, accessible, and great sources of protein, vitamin B12, vitamin D, omega-3 fatty acids, and a slew of other nutrients.
We already know eggs are good for our bones, muscles, and eyes. They’re also beneficial for our brains in numerous ways. A new study from researchers at the Loma Linda University in California has identified one of these: lowering our risk of Alzheimer’s disease.
We spoke to one of the study’s authors to learn more about what the research found and what it could mean for future Alzheimer’s prevention.
What was this study?
Researchers pulled data from a subgroup of the large prospective Adventist Health Study-2 (AHS-2), which includes health data from more than 96,000 adult members of the Seventh-day Adventist Church. Each participant completed a comprehensive 50-page questionnaire at enrollment about their diet, lifestyle habits, health conditions, and demographic information.
For this study, the researchers included only adults in AHS-2 who were 65 years or older and enrolled in Medicare—nearly 40,000 participants. They used information from their questionnaires, along with Medicare claims data between 2008 and 2020 to identify Alzheimer’s diagnoses and followed up on their health outcomes over 15 years.
What did the study find?
Looking specifically at their egg consumption, researchers categorized the participants into different groups, ranging from those who never or rarely ate eggs to those who ate an egg five or more times a week. After the 15-year follow-up, 2,858 were diagnosed with Alzheimer’s. They found that those who ate eggs had a lower risk of developing Alzheimer’s disease.
- Those who ate eggs at least five days a week had a risk reduction of up to 27%.
- Those who ate eggs two to four times a week had a 20% risk reduction.
- Those who ate eggs one to three times a month had a 17% risk reduction.
“Our study found that moderate egg consumption was associated with a significantly lower risk of developing Alzheimer’s disease,” says Jisoo Oh, DrPH, MPH, one of the study’s authors and an associate professor of epidemiology at Loma Linda University School of Public Health. “Compared to people who rarely or never consumed eggs, those who ate eggs regularly had lower risk of Alzheimer’s disease after accounting for many other dietary, lifestyle, and health factors.”
You don’t need to eat eggs by the dozen to reap the rewards. “One of the most notable findings was that even relatively modest egg intake appeared to be associated with benefit,” Oh explains. “Individuals reporting zero egg intake had a significantly higher Alzheimer’s disease risk compared with people consuming roughly the equivalent of about one egg per week.”
It’s worth mentioning that the research was co-funded by the National Cancer Institute and the American Egg Board, though a note in the study said the funding partners had no input on the study design, analysis, or any other part of the published research.
What’s significant about this group of people?
Seventh-day Adventists traditionally follow vegetarian or vegan diets, which is part of the Church’s religious doctrine. Their diets are mostly composed of whole plant foods: fruits, veggies, nuts, legumes, and whole grains. They also abstain from alcohol, caffeine, and tobacco.
Loma Linda in Southern California is home to a significant population of Adventists, and because of their healthy lifestyle, this group has been identified as one of the world’s six Blue Zones: places on the planet that are “hotspots” of longevity. People living in a Blue Zone regularly live very long lives with much lower rates of cancer, type 2 diabetes, obesity, and other chronic illnesses.
Generally speaking, the participants in AHS-2 are very healthy people. Looking at one small part of their diet could help researchers pinpoint a more specific way to reduce risk. But how did they know it was the eggs and not decades of healthy living?
Oh says the research team adjusted for a “wide range of potential confounding factors” that could have affected the findings, including age, lifestyle factors, body mass index, sleep, diet, and existing chronic medical conditions. Still, Oh adds, there’s no guarantee these variables didn’t have a residual effect over time that couldn’t clearly be measured.
How might eggs protect against Alzheimer’s?
Eggs have neuroprotective benefits, but it’s not clear which one or more of their nutrients are responsible for Alzheimer’s risk reduction. They contain several compounds that are good for brain health, which may be acting collectively and synergistically, according to the study. And we’re talking about the whole egg—yolks included—not just the whites. Here’s what’s inside:
- Choline produces acetylcholine and phosphatidylcholine (those are some serious tongue-twisters!), which are necessary for memory and synaptic function.
- Lutein and zeaxanthin are associated with improved cognitive performance and reduced oxidative stress.
- Tryptophan is converted into serotonin, which is involved in mood, cognition, and melatonin synthesis for sleep.
- DHA is an omega-3 fatty acid important for brain cell growth and the structural integrity of nerve cells.
- Vitamin B12 is a key nutrient for brain health. One egg provides about 25% of the recommended dietary allowance. People eating plant-based diets often don’t get enough B12. B12 deficiency is associated with elevated levels of neuroinflammation and homocysteine, both recognized Alzheimer’s disease risk factors.
One important caveat: This study found only a link between egg consumption and Alzheimer’s risk.
“It is important to emphasize that this was an observational study, so we cannot say eggs directly prevent Alzheimer’s disease,” Oh says. “We can only say that egg consumption was associated with lower risk.”
