For three decades, public health guidelines recommended limiting egg consumption due to their cholesterol content, based on the hypothesis that dietary cholesterol raised serum cholesterol and cardiovascular risk. This hypothesis has been substantially revised. The 2015 Dietary Guidelines Advisory Committee removed the recommendation to limit dietary cholesterol from US guidelines, stating that cholesterol is no longer a nutrient of concern for overconsumption. The egg is rehabilitated, and the nutritional case for eating the whole egg rather than the white alone is now clear.
What the Yolk Contains
The egg white provides protein. The yolk provides protein, fat-soluble vitamins A, D, E, and K, B12, choline, selenium, lutein, zeaxanthin, and all of the egg's zinc, calcium, and folate. Choline is particularly important for adults over 35: it is required for acetylcholine production (a key neurotransmitter for memory), for cell membrane integrity, and for methyl group donation in methylation pathways. It is also required for the transport of fat from the liver. Most adults do not consume adequate choline, and eggs are the most concentrated food source.
The Dietary Cholesterol Evidence
For approximately 75 percent of people, dietary cholesterol has minimal impact on serum LDL cholesterol because the liver downregulates its own cholesterol synthesis in response. The remaining 25 percent are hyperresponders who do see LDL increases with high egg intake. This variability is genetically determined and is largely linked to the ApoE4 genotype. For the majority of adults, consuming two to three whole eggs per day is not associated with increased cardiovascular risk.