Eggs, a long-time staple of the American diet, are making a comeback after years of being maligned as a major source of dietary cholesterol. And their nutritional story is stronger than ever, as research on lutein and satiety sheds light on health-promoting qualities of eggs that go beyond their well-known protein and nutrient content.

"Egg consumption has been going up steadily since 1995," says Donald McNamara, Ph.D., executive director, Egg Nutrition Center, Washington, D.C. " In 1995, consumption was 235 eggs per person per year and in 2003, it was 259 eggs per person per year."

The one-two punch of the Dallas-based American Heart Association's (AHA) guidelines that no longer recommend a specific number of egg yolks to consume in a week and research that reinforces eggs as a nutritional powerhouse means "people now have permission and a reason to eat eggs," according to McNamara.

Egg nutrition basics

Eggs offer high-quality protein and numerous essential nutrients in an economical energy package. Two large eggs provide only 6% of the Daily Value (DV) for energy, but 20% of the DV for protein. They rate as an excellent source of riboflavin, vitamin K and selenium, as well as a good source of phosphorus and vitamins B12, D, A, and folate. Additionally, they contribute iron, zinc, vitamins E and B6. This nutrient density makes eggs a nutritional asset in a well-balanced diet (Journal of the American College of Nutrition, Vol. 19, No. 5). In fact, a study on the nutritional contribution of eggs to American diets using NHANES III data, (1988 to 1994) showed that egg consumers had higher intakes of nutrients, except dietary fiber and vitamin B6, with eggs contributing less than 10% of energy and vitamin B6, 10% to 20% of total saturated and polyunsaturated fat and folate, and 20% to 30% of vitamins A, E and B12 (Journal of the American College of Nutrition, Vol. 19, No. 5).

Egg lipids and initial interpretations on the role of dietary cholesterol in coronary heart disease (CHD) created uncertainty and confusion about eggs as part of a healthful diet. While one large egg contains 213 mg of cholesterol, or 71% of the 300 mg recommended as an average daily intake, its fat and saturated-fat content represent only 8% of the DV at 5.0 grams and 1.5 grams, respectively. Analyses of the connection between dietary and serum cholesterol reveal that other dietary factors, like saturated and trans fats, exert a greater influence on serum-cholesterol levels and risk for CHD and that dietary cholesterol poses little if any risk for heart disease. When studies on the relationship between egg consumption and risk for CHD factored in dietary confounders, eating up to 1-plus eggs a day was not associated with CHD in nondiabetics (Journal of the American College of Nutrition, Vol. 19, No. 5). Thus, current recommendations from the AHA place no restriction on eggs in a heart-healthy diet for the general public.

Eggs also represent a significant source of choline in the diet. Choline, recognized as an essential nutrient in 1998 when the Institute of Medicine of the National Academy of Sciences recommended an Adequate Intake (AI) level for it, plays a multitude of roles involving cell membranes, nerves, lipid transport/metabolism and memory function. During pregnancy and infancy, it is critical to brain and nervous-system development. Two eggs provide 560 mg of choline, which meets or exceeds the AI for all age groups, as well as pregnant and lactating women.

Eggs as a functional food

According to McNamara, two current areas of egg-nutrition interest are eye health and egg's effect on satiety. "One paper from Tufts that was published last September shows that lutein in eggs has high bioavailability," says McNamara. "If you eat the same amount of lutein as in spinach, blood levels were three times higher from eggs. It is also easier to absorb." Lutein and zeaxanthin, also found in eggs, are carotenoids associated with reduced risk for cataracts and age-related macular degeneration.

Another study reported at the Experimental Biology meeting in 2003 showed a significant increase in the macular pigment optical density and an increase in serum lutein and zeaxanthin in seven subjects consuming an egg supplement (six eggs per week) compared to six subjects on a placebo pill. McNamara points out that this demonstrates that not only is the lutein in eggs more bioavailable, but it also has functional value in the macula. "There are other reports that lutein is related to cataracts," he continues. "In the Beaver Dam Eye Study, higher egg consumption was associated with lower risk for formation of cataracts." So for eye health, "consumers have a choice of spinach, kale or broccoli or eggs," he notes.

It also appears that eggs could play a role in curbing obesity. McNamara cites a study reported at the North American Society for the Study of Obesity meeting in Nov. 2004 that showed that having eggs at breakfast resulted in higher satiety in a group of women, who then ate less at lunch. The subjects were given isocaloric meals of equal weight with eggs, either toast and jelly or bagel and cream cheese, and yogurt. Energy intake at lunch following the egg breakfast was reduced by 29% vs. the bagel breakfast. Food records for the following 24 hours did not demonstrate a compensatory increase in energy intake. McNamara says that other studies have also demonstrated that egg yolks have greater satiety value and reduced blood-sugar and insulin responses.

For decades, manufacturers worked to find ingredients that provided the functionality and taste of egg yolks in response to health recommendations and consumer interest in low cholesterol. Current research indicates that only those who are allergic to eggs or who have medical conditions, such as hypercholesterolemia and other conditions that make them susceptible to CHD, need to avoid or limit egg-containing foods. As researchers uncover additional health benefits in eggs and consumers become more cognizant of them, eggs as a meal or as ingredients should rise in stature and acceptance by consumers, allowing the full return of eggs and all their functional aspects.