Eating two to four eggs a week could help lower blood cholesterol levels, and improve memory, according to researchers at the University of California San Diego who analysed the health data of 890 men and women.
Their review is based on data from a healthy ageing study that began in 1988 and which tested three aspects of cognitive function in middle-aged or older adults over the course of four years.
Of all 531 women considered, those who reported eating more eggs showed less of a decline in short- and long-term memory.
No such association was found among men who ate more eggs. That said, another data analysis using the same database but a cohort from a different decade did find that men who ate more eggs scored better on cognitive tests, whereas no association was found for women.
This suggests other factors are also at play that need to be cleared up by further research, reports Science Alert.
Public health researchers Donna Kritz-Silverstein and Ricki Bettencourt from UCSD said that “despite having high levels of dietary cholesterol”, their results show “eggs do not have a detrimental effect and may even have a role in the maintenance of cognitive function over time”.
For nearly half a century, people were advised to avoid animal products high in cholesterol – like eggs, butter, or cream – because these were thought to raise cholesterol levels in the blood, increasing the risk of cardiovascular disease.
While that advice may still stand for some people with certain health conditions, like diabetes, emerging evidence suggests it’s really saturated fats, sugar, and sodium that are the main contributors to plaque build-up in the arteries, not dietary cholesterol.
The trouble is, many foods rich in cholesterol also deliver a hearty dose of saturated fats. Eggs and shellfish are two key exceptions, depending on how they are cooked.
In fact, eggs are low-fat, high-protein, nutrient-dense foods that could actually lower your body’s cholesterol levels, an effect that seems to help protect against cognitive decline.
Perhaps that is one reason why eating eggs was linked to slightly improved cognitive test scores among women in the recent analysis, but further research is needed to explore that association.
Kritz-Silverstein and Bettencourt point out in their paper, published in Nutrients, that eggs are rich in proteins, amino acids, and cholesterol, and these factors could possibly work to preserve neuron structure and function in the brain.
Eggs also contain carotenoids, which are linked to improved cognitive performance, and they are packed with choline, which is a precursor to a crucial neurotransmitter.
“Cross-sectional studies have shown that those with greater choline intake and those with higher plasma concentrations of choline had better scores on several measures of cognitive function,” said the pair.
There are still unanswered questions about the nutritional benefits of eggs, but these findings provide additional evidence that if a food is high in cholesterol, that doesn’t always mean it’s bad for your body or your brain.
Study details
Egg Consumption and 4-Year Change in Cognitive Function in Older Men and Women: The Rancho Bernardo Study
Donna Kritz-Silverstein and Ricki Bettencourt.
Published in Nutrients on 19 August 2024
Abstract
The effect of dietary cholesterol on cognitive function is debatable. While eggs contain high levels of dietary cholesterol, they provide nutrients beneficial for cognitive function. This study examined the effects of egg consumption on change in cognitive function among 890 ambulatory adults (N = 357 men; N = 533 women) aged ≥55 years from the Rancho Bernardo Study who attended clinic visits in 1988–1991 and 1992–1996. Egg intake was obtained in 1988–1991 with a food frequency questionnaire. The Mini-Mental Status Exam (MMSE), Trails B, and category fluency were administered at both visits to assess cognitive performance. Sex-specific multiple regression analyses tested associations of egg intake with changes in cognitive function after adjustment for confounders. The mean time between visits was 4.1 ± 0.5 years; average ages were 70.1 ± 8.4 in men and 71.5 ± 8.8 in women (p = 0.0163). More men consumed eggs at higher levels than women; while 14% of men and 16.5% of women reported never eating eggs, 7.0% of men and 3.8% of women reported intakes ≥5/week (p = 0.0013). In women, after adjustment for covariates, egg consumption was associated with less decline in category fluency (beta = −0.10, p = 0.0241). Other associations were nonsignificant in women, and no associations were found in men. Results suggest that egg consumption has a small beneficial effect on semantic memory in women. The lack of decline observed in both sexes suggests that egg consumption does not have detrimental effects and may even have a role in the maintenance of cognitive function.
See more from MedicalBrief archives:
Swopping eggs for nuts could cut CVD risk – German review
Egg and cholesterol consumption and mortality – US population-based cohort study
Dairy products may protect against type 2 diabetes – Italian meta-analysis