Egg consumption linked to slower cognitive decline in women

By Priyanjana Pramanik, MSc.Reviewed by Lily Ramsey, LLMAug 22 2024

In a recent study published in Nutrients, researchers investigated the effects of egg consumption on cognitive function in older adults.

Their findings indicate that eating eggs may help maintain cognitive function, particularly semantic memory, among women without any detrimental effects observed in either sex.

Study: Egg Consumption and 4-Year Change in Cognitive Function in Older Men and Women: The Rancho Bernardo Study. Image Credit: Josep Suria/Shutterstock.com

Background

Alzheimer’s disease and various forms of memory impairment are becoming increasingly common, especially among older adults, with more than 6.9 million Americans over 65 years old affected in 2024. Researchers expect this number to double by 2060 due to the aging population.

Since aging is inevitable, it is critical to find lifestyle changes that could reduce cognitive decline risk. Research shows that high cholesterol levels in midlife can double the chance of developing cognitive issues later, but the link between cognitive decline and dietary cholesterol is unclear.

Eggs, which are high in cholesterol but, unlike meat, low in fat, also contain nutrients like carotenoids and choline that support brain health.

However, studies on the impact of egg consumption on cognitive function have produced mixed results, with some showing benefits, some showing effects for men but not women, others showing no effect, and some showing no link over time.

About the study

In this study, researchers explored the relationship between egg consumption and cognitive function, focusing on changes over time.

They utilized data from the Rancho Bernardo Study, which followed a prospective-cohort design and included middle- and upper-middle-class adults living in Southern California.

Participants were selected based on their egg consumption and performance on cognitive evaluations during visits that took place in 1988–1991 and 1992–1996. After excluding participants under 55, those with missing data, and those who had suffered a stroke, 890 participants (533 women and 357 men) were included in the analysis.

Cognitive function was assessed using three tests: the Mini-Mental State Examination (MMSE), which is used to evaluate overall cognitive function through registration, attention, orientation, recall, language, and calculation.

The Trail-Making Test, Part B (Trails B), which evaluates executive functions such as mental flexibility, attention, and visuomotor tracking, and a category fluency test, which measures verbal fluency and semantic memory, involves participants listing animals from memory for one minute.

Researchers recorded egg consumption using a food frequency questionnaire, and the participants’ diet, lifestyle, and medical history were also considered. Sex-specific analyses were conducted due to the possibility of differences between men and women.

The researchers used linear regression to explore the relationship between egg consumption and changes in cognitive performance, adjusting for variables like age, education, lifestyle behaviors, and nutrient intake.

Findings

The study found that egg consumption had a different impact on cognitive function between men and women.

On average, women who ate more eggs experienced a smaller decline in verbal fluency over four years.

Specifically, for each increase in egg consumption, there was a slight but significant reduction in the deterioration of their category fluency scores, meaning that women who ate more eggs maintained their ability to name categories of items, like animals, better than those who ate fewer or no eggs.

This association remained significant even after accounting for factors like age, education, diet, lifestyle behaviors, and health conditions.

However, egg consumption did not significantly affect other cognitive measures like the MMSE or the Trails B Test, nor was there any significant impact on cognitive function in men.

The findings suggest that while egg consumption might help protect certain cognitive abilities in women, it does not seem to have a broad impact on overall cognitive health in older adults.

Conclusions

The study highlights the potential benefits of egg consumption for maintaining cognitive function in older women.

Women who ate more eggs experienced less decline in verbal fluency over four years, even after accounting for various lifestyle and health factors. This finding is significant, given the rising concern over cognitive decline as people live longer.

The study’s results align with previous research but add a unique perspective by focusing on sex-specific differences in a U.S. cohort. However, no similar benefits were observed in men, which is consistent with other studies showing no link between egg consumption and cognitive decline in men.

The study has several strengths, including a large sample size, well-characterized participants, and sex-specific analyses. However, limitations include the homogeneity of the study population, reliance on self-reported data, and the relatively short follow-up period.

Despite these limitations, the findings suggest that eggs could be a cost-effective and accessible way to support cognitive health in women.

Future research should focus on longer-term studies with diverse populations, including brain imaging, to further explore the relationship between egg consumption and cognitive function.