Eggs and choline — does the yolk protect the brain and memory?

Aim of the study: Brain development is an ongoing process that occurs throughout the first 1000 days of life (from conception to age 2) and continues through childhood and adolescence until early adulthood. Adequate nutrient intake is crucial both for neurodevelopment in the womb and during the critical stages of life that follow, when the brain continues to grow and develop.

Results: Eggs also provide a range of nutrients and bioactive components, including docosahexaenoic acid, choline, lutein and zeaxanthin, which may support brain growth and development. Given their nutrient-dense profile, eggs could be encouraged at life stages when the brain is under particular demands for development, growth and function. These include women of childbearing age, infancy, childhood and adolescence. However, more research is needed to determine how much egg intake can affect specific measures of brain and cognitive function.

Aim of the study: In recent years, interest in the relationship between diet and cognitive function has increased. In this regard, eggs contain many essential nutrients that also benefit cognitive function.

Results: Choline from eggs is needed to make acetylcholine, a neurotransmitter involved in memory and learning. It is also needed to make phosphatidylcholine, intake of which has been linked to better mental function and a lower risk of dementia in adults. Choline intake during pregnancy reduces the risk of neural tube defects and is associated with better development in children. Lutein and zeaxanthin, which are particularly concentrated in the nervous system, are associated with better visual function and cognitive development in children, as well as in older people. All this evidence confirms the importance of including eggs in a balanced diet to prevent cognitive decline and support cognitive health throughout life.

Aim of the study: In observational studies, moderate egg intake has been associated with better cognitive performance. This association may be due to the high choline content of eggs, especially phosphatidylcholine, because choline is thought to play a role in preventing cognitive decline.

Results: Mean ± SD total choline intake was 431 ± 88 mg/d, of which 188 ± 63 mg/d was phosphatidylcholine. During a 21.9-year follow-up, 337 men were diagnosed with dementia. Compared with men in the lowest quartile of phosphatidylcholine intake, those in the highest quartile had a 28% lower multivariable-adjusted risk of developing dementia (95% CI: 1%, 48%; P-trend = 0.02 across quartiles). Total choline intake was not associated with the risk of developing dementia. However, both total choline and phosphatidylcholine intake were associated with better performance on cognitive tests assessing frontal and temporal lobe function. For example, higher intakes were associated with better verbal fluency and memory. The APOE phenotype had little or no effect on these associations. Higher phosphatidylcholine intake was associated with a lower risk of developing dementia and better cognitive performance in men in eastern Finland. This trial was registered at clinicaltrials.gov as NCT03221127.

Aim of the study: Dietary choline is associated with a lower risk of dementia in older adults, but whether this is also true in midlife is unknown. Since menopause is a stage when nutrition may be especially important and prevention strategies could reduce cognitive difficulties, we examined the relationship between choline, betaine and egg intake (dietary exposures) and cognitive performance in the Study of Women's Health Across the Nation (SWAN) cohort (N = 1,006).

Results: Among all women, higher intakes of choline (P-for-trend = 0.006) and betaine (P-for-trend = 0.005), both independently and combined (choline + betaine; P-for-trend = 0.001), were significantly associated with a slower rate of change on the EBMT-Delayed Recall (DR), but egg intake did not consistently affect cognitive function. By menopausal status, higher betaine intake, but not choline intake, was associated with a lower annual rate of change in cognitive performance on the EBMT-DR among women in early perimenopause (mean difference [95% confidence interval]; Q1: reference vs Q4: -0.071 [-0.17, 0.03]; P-for-trend = 0.006). However, choline and betaine were not associated with cognitive function among premenopausal women.