Eggs whites, and eggs in general, are an inexpensive source of high-quality protein. When deciding whether you want to eat just the egg white or the whole egg, consider the nutrient content and potential health implications of your choice. For healthy people, it may sometimes be a good idea to eat more than just the white. Your doctor can advise you on how many egg yolks you can safely eat given your current health situation.
Substituting two egg whites for a whole egg will save you some fat, cholesterol and calories while still providing you with plenty of protein. Two egg whites contain 34 calories, just trace amounts of fat, more than 7 grams of protein and no cholesterol. A whole egg has 72 calories, almost 5 grams of fat, 186 milligrams of cholesterol and more than 6 grams of protein. This is 7 percent of the daily value for fat and 62 percent of the daily value for cholesterol.
Vitamins and Minerals
Eating two egg whites will provide you with 18 percent of the daily value for riboflavin and selenium, but little if any of the other essential micronutrients. A whole egg is a better source of micronutrients in general, providing 13 percent of the DV for riboflavin, 10 percent of the DV for phosphorus, 22 percent of the DV for selenium and smaller amounts of most other essential vitamins and minerals with the exception of vitamins C and K.
Riboflavin helps turn the food you eat into energy, acts as an antioxidant and helps make red blood cells. You need phosphorus for proper heart, nerve muscle and kidney function, and selenium is essential for forming DNA and proper thyroid function.
Eggs and Cholesterol
Egg yolks have been given a bad reputation due to their high cholesterol content, but eggs don't necessarily increase blood cholesterol in everyone. In about 70 percent of people, eggs cause little or no increase in blood cholesterol even when consumed in high amounts, according to an article published in Current Opinion in Clinical Nutrition and Metabolic Care in January 2006.
Saturated and trans fats are more likely to cause increases in blood cholesterol than dietary cholesterol. The Scientific Report of the 2015 Dietary Guidelines Advisory Committee recommended no longer including a warning in the Dietary Guidelines for Americans about dietary cholesterol because it doesn't have a significant impact on blood cholesterol levels.
A study published in Metabolism in March 2013 found that people with metabolic syndrome who ate three whole eggs per day along with a reduced-carbohydrate diet for 12 weeks experienced greater improvements in insulin sensitivity and cholesterol than those who ate the equivalent amount of egg substitute made with just egg whites. This was just a small, short study, however, so further research is necessary to verify these effects.
People at risk for cataracts and macular degeneration may benefit from eating egg yolks in moderation because they contain the antioxidants lutein and zeaxanthin, which help limit the risk for these conditions, according to the Current Opinion in Clinical Nutrition and Metabolic Care article.
The University of California Berkeley notes that most people can eat about an egg a day without adverse effects. The Harvard School of Public Health recommends people with high cholesterol and those with diabetes stick with egg whites most of the time and eat no more than three yolks per week.
You'll offset any potential health benefits from eggs, however, if you prepare them or serve them with lots of fatty foods, such as bacon, sausage, hash browns and butter. Scrambled, poached and hard-cooked eggs are better choices than fried eggs or omelets filled with meat and cheese.