Some nutritionists have compared the egg to a multivitamin because it contains small amounts of virtually every vitamin and mineral needed by the human body – calcium, iron, potassium, zinc, manganese, vitamin E and folate. In addition, it contains significant amounts of vitamin B12 (9 percent of recommended daily allowance), vitamin B2 (15 percent), vitamin A (6 percent), vitamin B5 (7 percent) and selenium (22 percent).
Egg yolks, along with beef liver, are the two principal sources of choline, a nutrient essential for brain and cardiovascular health. Low choline intake can result in inflammation, liver disease and, in pregnant women, a risk of birth defects.
Lutein and zeaxanthin
Other nutrients found in egg yolks include lutein and zeaxanthin, which have important benefits for the eyes, reducing the risk of both macular degeneration and cataracts. Lutein also protects against the early progression of heart disease, according to the American Heart Association.
And eggs may be beneficial to heart health in other ways, as well. They tend to raise HDL (the good cholesterol) and increase the size of LDL particles, making them less likely to pose a heart risk.