Egg yolks contain a rich array of essential vitamins and minerals, particularly vitamins A, D, E, B12 and K, riboflavin, folate and iron, while the whites are a great source of low-calorie protein. The egg's tarnished reputation comes from the cholesterol the yolk contains. In 1973, the American Heart Association began urging us to cut down on our egg consumption as a means of protecting against heart disease, which is associated with increased cholesterol levels.
That’s no longer necessary. We now know that the cholesterol in egg yolks doesn’t have much influence on serum cholesterol levels and by extension the risk of heart disease. As long ago as 1999, a study from the Harvard School of Public Health published in the Journal of the American Medical Association found no increased risk of coronary heart disease or stroke among healthy men and women who ate as many as seven eggs per week compared to those who ate fewer than one per week. The researchers tracked over 117,000 American adults for up to 14 years to reach their conclusion. They did find what appeared to be a correlation between high egg consumption and heart disease among diabetic men and women.
More recent research suggests that saturated and trans fats– not cholesterol from foods - are the dietary factors most responsible for increased cholesterol levels, although the association with saturated fat is now in question.
Based on what we now know, if you enjoy eggs, I see no reason why you shouldn’t eat them – including the yolks – several times a week. I advise choosing omega-3 enriched eggs from organically raised chickens. To get the omega-3s into the eggs, manufacturers of chicken food add algae, ground flaxseeds or fish oil. Essential fatty acids such as omega-3s cannot be made by our bodies and must be obtained from the diet. We need these healthy fats for optimal brain growth and development. They also have anti-inflammatory effects that may reduce the risk of cardiovascular disease, arthritis, high blood pressure, tumor growth and diabetes. Organic eggs come from chickens that eat food containing no pesticides herbicides, fungicides and commercial fertilizers. The hens are never given antibiotics, and are cage-free with access to the outdoors. Organic chicken feed contains no animal byproducts.
It is also important to be prudent about what you eat with your eggs. Home fries or white toast with sugary jam are sources of unhealthy fats and high-glycemic-load carbs with health effects that won’t be neutralized by the nutritional benefits of eggs.
Andrew Weil, M.D.