In a recently published study Nutritional valuesResearchers investigated the effects of egg consumption on cognitive function in older adults.
Their results suggest that egg consumption may contribute to the maintenance of cognitive functions, particularly semantic memory, in women, without adverse effects observed in either sex.
Study: Egg consumption and 4-year change in cognitive function in older men and women: The Rancho Bernardo studyPhoto credit: Josep Suria/Shutterstock.com
background
Alzheimer’s disease and various forms of memory impairment are becoming increasingly common, especially among older people. In 2024, more than 6.9 million Americans over the age of 65 will be affected. Researchers expect this number to double by 2060 due to the aging population.
Because aging is inevitable, it’s important to find lifestyle changes that can reduce the risk of cognitive decline. Research shows that high cholesterol in midlife can double the chance of developing cognitive problems later in life, but the link between cognitive decline and dietary cholesterol is unclear.
Eggs are high in cholesterol but, unlike meat, are low in fat and also contain nutrients such as carotenoids and choline, which support brain health.
However, studies on the effects of egg consumption on cognitive function have found mixed results: some showed a positive effect, others showed an effect in men but not in women, others showed no effect, and still others showed no association over time.
About the study
In this study, researchers examined the relationship between egg consumption and cognitive function, focusing on changes over time.
They used data from the Rancho Bernardo study, which followed a prospective cohort design and included middle- and upper-middle-class adults in Southern California.
Participants were selected based on their egg consumption and performance on cognitive tests during visits between 1988 and 1991 and between 1992 and 1996. After excluding participants younger than 55, participants with missing data, and participants 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 assesses general cognitive function using registration, attention, orientation, memory, language, and calculation.
The Trail-Making Test, Part B (Trails B), which assesses executive functions such as mental flexibility, attention, and visual-motor tracking, and a Category Fluency Test, which measures verbal fluency and semantic memory, require participants to list animals from memory for one minute.
The researchers recorded egg consumption using a food frequency questionnaire. The participants’ diet, lifestyle and medical history were also taken into account. Gender-specific analyses were conducted due to possible differences between men and women.
The researchers used linear regression to investigate the relationship between egg consumption and changes in cognitive performance, taking into account variables such as age, education, lifestyle and nutrient intake.
Results
The study found that egg consumption had different effects on cognitive function in men and women.
On average, women who ate more eggs experienced a smaller decline in verbal fluency over four years.
With each increase in egg consumption, the decline in their scores on category competence decreased slightly but significantly. This means that the women who ate more eggs retained their ability to name categories of objects, such as animals, better than those who ate fewer or no eggs.
This association remained significant even when factors such as age, education, diet, lifestyle and health status were taken into account.
However, egg consumption had no significant effect on other cognitive measures such as the MMSE or the Trails B test, nor were there significant effects on cognitive function in men.
The results suggest that while egg consumption may help protect certain cognitive abilities in women, it does not appear to have a major 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 had less decline in verbal ability over four years, even after controlling for various lifestyle and health factors. This finding is significant because concern about cognitive decline increases with age.
The study’s findings are consistent with previous research but offer a unique perspective by focusing on gender differences in a U.S. cohort. However, similar benefits were not observed in men, which is consistent with other studies showing no association between egg consumption and cognitive decline in men.
The study has several strengths, including a large sample, well-characterized participants, and gender-specific analyses. However, limitations include the homogeneity of the population studied, the reliance on self-reported data, and the relatively short follow-up period.
Despite these limitations, the results suggest that eggs may 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 association between egg consumption and cognitive function.
