The yolk of the egg is a rich source of lutein and zeaxanthin, relatives of beta carotene, that may help keep eyes healthy that have been linked to a reduced risk of age-related macular degeneration.
Eggs are climbing up out of decades of disrepute from the fresh-food-and-fats-phobic late-20th century, where incomplete science left eggs with a bad reputation, mostly because they contain dietary cholesterol.
But scientists now know that dietary cholesterol does not clog arteries, and can actually help unclog arteries (except in a small percentage of people termed cholesterol sensitive because their blood cholesterol levels rise when they eat foods high in cholesterol). Even here, because the egg white is an almost-pure high-quality protein, a cholesterol-sensitive person can skip the yolk and eat only the white.
Not all eggs are created equal, however, and their quality depends on the health of the chickens laying them, making it well worth the slight price hike we pay for free-range and organic eggs.
A medium egg contains less than 80 calories, making eggs a good choice, for those watching their weight, in everything from egg salad to eggs that are boiled, scrambled or poached. Because they are packed with protein, eggs promote a sense of fullness; one study, in Nutrition Research, found that participants who ate scrambled eggs for breakfast felt fuller afterwards, and consumed significantly fewer calories over the course of the day, than did those who ate a bagel-based breakfast with the same number of calories.
Even at their lowest point on the popularity scale, eggs remained in most of our diets, thanks to the unique food chemistry, provided by their bright yellow yolks and translucent filmy whites, making them indispensable in everything from sauces to baked goods and side dishes.
Health safety concerns about eggs come from the fact that the salmonella bacteria, transferred from the laying-hen’s intestines, can be present, even in clean, uncracked eggs. To destroy this food-poisoning bacteria, eggs should be cooked at high temperatures. Soft-cooked, sunny-side up and raw eggs can carry salmonella; hard-boiled, scrambled and poached eggs do not. (For a differing opinion on the need to cook eggs, see Ask an Expert, above.)
Another potential problem lies in raw egg whites, which contain the glycoprotein avidin that prevents the absorption of the essential water-soluble B vitamin biotin, believed to speed up metabolism and help control diabetes. Cooking the egg takes care of the biotin-absorption problem.
Egg allergies, caused by a reaction against the egg white’s proteins and mostly found in infants and toddlers, tend to fade by age 3, and are a common culprit in infantile eczema. Often egg-allergic infants display allergies to other foods as well, including cow’s milk protein and peanuts. Most children with egg allergies show a natural aversion to foods containing eggs, complaining that eggs taste bitter, and of such unusual reactions as a tingling in the mouth. The more the egg is cooked, the less likely it is that your child will have an allergic reaction. But some infants and children remain highly allergic to eggs – even when baked – and a reaction can be triggered just by being in a kitchen where eggs have been cooked, or coming into contact with the hands or lips of someone who has eaten or touched egg or using utensils used to cook eggs. For those individuals, a commercial egg substitute can be used in baking. Allergic reactions are usually immediate, including skin rash, hives, itching, and eczema; a swelling of the lips, tongue, or throat; tingling in the mouth; wheezing or nasal congestion; trouble breathing; and dizziness or lightheadedness. But food allergy symptoms can also be more general, and slower to manifest, including fatigue, depression, chronic headache, chronic bowel problems (such as diarrhea or constipation), and insomnia.
It is recommended that dishes and utensils used when preparing eggs be washed in warm water separately from other kitchenware, and that hands are washed with warm, soapy water. Surfaces that come into contact with raw egg should be washed and sanitized with a solution of 1 teaspoon chlorine to 1 quart water.