Choline is an essential nutrient critical for various bodily functions, including brain development, liver health, and muscle function. It acts as a precursor to acetylcholine, a neurotransmitter involved in memory, attention, and muscle control. Choline also contributes to the synthesis of phospholipid membranes and serves as a source of methyl groups necessary for metabolic processes. While the body can produce small amounts of choline, most of it must come from the diet to meet physiological needs.

The benefits of choline are wide-ranging. During pregnancy, adequate choline intake supports fetal brain development and may enhance memory, attention, and visual-spatial learning in children. It also plays a role in cardiovascular health by reducing the risk of heart disease and stroke. Additionally, sufficient choline levels have been linked to improved cognitive function and may lower the risk of cognitive decline and dementia. For athletes, choline is vital for muscle control and may influence strength and lean mass gains in response to exercise.

Choline is found in both animal- and plant-based foods, with eggs being an especially rich source—one large egg provides approximately 147 mg. Other sources include meat, poultry, fish, dairy products, cruciferous vegetables, beans, nuts, seeds, and whole grains. The recommended daily intake of choline is 550 mg for men and 425 mg for women, increasing to 450 mg and 550 mg, respectively, during pregnancy and lactation. While rare, choline deficiency can occur, particularly in pregnant and lactating women, postmenopausal women with lower estrogen levels, and individuals with genetic variants affecting choline metabolism.

Excessive choline intake, however, can lead to side effects such as fishy body odor, vomiting, excessive sweating and salivation, low blood pressure, and liver toxicity. It may also increase the production of trimethylamine N-oxide (TMAO), a compound associated with cardiovascular disease. Despite this, moderate consumption of foods like eggs—up to three per day—has not been shown to elevate plasma TMAO levels For optimal health, individuals should focus on meeting, but not greatly exceeding, the recommended daily intake of choline, ensuring they obtain it through a balanced diet rich in both animal and plant-based foods.

Choline is essential for brain health

"When it comes to brain health, dietary choline is associated with lower risks for cognitive impairment, post-stroke depression, and dementia. Early childhood choline intake appears to be especially important for neurodevelopment, memory, attention, and learning." Click To Tweet

Choline is an essential dietary nutrient that serves as a precursor for methylation, affecting epigenetics globally, and plays a role in the production of the neurotransmitter acetylcholine. Choline is also converted into phosphatidylcholine, a crucial component of cell membranes that regulates intracellular transportation. Choline literally makes up the stuff of our brain and cells.

When it comes to brain health, dietary choline is associated with lower risks for cognitive impairment, post-stroke depression, and dementia. Early childhood choline intake appears to be especially important for neurodevelopment, memory, attention, and learning. For children and adults at every stage of life, dietary choline should be a focus, especially for those concerned with mitigating cognitive decline that can often accompany getting older.

Eggs as part of a healthy diet

Eating more eggs might be one of the easiest things one can do to improve their health—particularly that of the brain.

They're rich in brain-boosting nutrients like choline and the carotenoids lutein and zeaxanthin, as well as omega-3 fatty acids.

However, some people are concerned that eating too many eggs could elevate cholesterol levels to a dangerous range and therefore, increase cardiovascular disease risk. This concern is mostly abated by evidence that generally fails to support an association between egg intake and cardiovascular disease risk.

The amount of dietary cholesterol that gets converted into cholesterol in the body and the blood is miniscule. Though egg yolks contain high levels of cholesterol, eating more eggs doesn't appear to raise one's cholesterol or elevate the risk for cardiovascular disease independent of other risk factors. In fact, the American Heart Association concludes that eating 2 eggs per day is safe and is actually associated with a lower risk of stroke and other cardiovascular diseases.

When it comes to eggs,the focus should be less on cholesterol and more on the powerhouse nutrients they contain—protein, omega-3 fatty acids, carotenoids, and of particular importance for brain health, choline. Eggs are without a doubt the top dietary source of choline—a single egg contains almost 150 mg of choline, nearly one third of the daily recommended intake for adults.

This begs the question: Could eating eggs benefit brain health?

Eating eggs mitigates cognitive decline

"...among women—those consuming 5 or more eggs per week had a nearly half-point less decline compared to those in the lowest category of egg intake (never). This was even after controlling for confounding variables like age, education, smoking and alcohol, exercise, cholesterol, and dietary calories and protein." Click To Tweet

In one study, a higher egg intake was associated with less decline in verbal fluency over 4 years among women—those consuming 5 or more eggs per week had a nearly half-point less decline compared to those in the lowest category of egg intake (never). This was even after controlling for confounding variables like age, education, smoking and alcohol, exercise, cholesterol, and dietary calories and protein.

This study involved 890 older adults (average age of ~70) from a community in Southern California. Based on a self-reported dietary questionnaire, they were placed into one of five categories of egg consumption:

• Never
• 1–3 per month
• 1 per week
• 2–4 per week
• More than 5 per week

At the start of the study and 4 years later, all of the participants took tests to evaluate their global cognitive function, executive function, and verbal fluency.

Although a higher egg intake mitigated the decline in verbal fluency, changes in global cognitive function and executive function among women in the study weren't different and for men, there was no association between egg intake and 4-year changes in cognitive function measures.

These findings might seem underwhelming, but one of the main reasons for the lack of an effect could be the relatively low egg intake among the participants—nearly 15% of them never consumed eggs and only 3–7% of them consumed more than 5 per week, which is still less than once per day. There were only small differences in egg consumption between the groups, which may not have been robust enough to alter the trajectories of cognitive function during the study.

Eating eggs reduces Alzheimer's disease risk

"An analysis of brain samples from participants who died during the study revealed that consuming 1 or more eggs per week reduced the odds of having a pathological diagnosis of Alzheimer’s disease by up to 49%—indicated by the presence of fewer plaques and neurofibrillary tangles." Click To Tweet

Another study showed that during a nearly 7-year follow-up period, consuming just one egg per week was associated with a 47% reduction in the risk of developing Alzheimer’s disease. A 47% reduction in risk was also observed for participants who consumed two or more eggs per week compared to those who consumed less than 1 egg per week.

This study involved 1,024 participants with an average age of 81—82% of whom carried the APOE e4 allele (the number one genetic risk factor for developing late-life Alzheimer's disease. The participants were given a dietary assessment that included questions about their habitual egg intake.

It wasn’t just the diagnosis of Alzheimer’s disease that was lower among participants consuming one or more eggs per week—their brains also exhibited fewer pathological signs of the disease. An analysis of brain samples from participants who died during the study revealed that consuming 1 or more eggs per week reduced the odds of having a pathological diagnosis of Alzheimer’s disease by up to 49%—indicated by the presence of fewer plaques and neurofibrillary tangles.

This finding may be particularly important because a pathological diagnosis is considered to be a more accurate and confirming diagnosis of Alzheimer’s disease. Not all participants diagnosed with Alzheimer’s disease when they were alive showed pathological signs of Alzheimer’s disease after death, and some participants without a clinical diagnosis showed pathological signs of Alzheimer's disease post mortem.

Egg intake was also associated with a longer disease-free lifespan—Alzheimer's diagnosis was delayed by 34% among participants consuming 2 or more eggs per week compared to those who reported consuming less than 1 egg per month or never.

Lastly, nearly 40% of these effects were directly mediated by choline, highlighting the critical importance of this nutrient for brain health and reducing neurodegenerative disease burden.