The health benefits of... eggs
The humble egg has impressive health credentials. Nutritionist Jo Lewin shares recipes, nutritional highlights and tips on choosing a good egg.
An introduction to eggs...
Both the white and yolk of an egg are rich in nutrients - proteins, vitamins and minerals with the yolk also containing cholesterol, fat soluble vitamins and essential fatty acids. Eggs are an important and versatile ingredient for cooking, as their particular chemical make up is literally the glue of many important baking reactions.
Since the domestication of the chicken, people have been enjoying and nourishing themselves with eggs. As a long time symbol of fertility and rebirth, the egg has taken its place in religious as well as culinary history. In Christianity, the symbol of the decorated egg has become synonymous with Easter. There are lots of different types of egg available, the most commonly raised are chicken eggs while more gourmet choices include duck, goose and quail eggs.
Eggs are a very good source of inexpensive, high quality protein. More than half the protein of an egg is found in the egg white along with vitamin B2 and lower amounts of fat and cholesterol than the yolk. The whites are rich sources of selenium, vitamin D, B6, B12 and minerals such as zinc, iron and copper. Egg yolks contain more calories and fat. They are the source of cholesterol, fat soluble vitamins A, D, E and K and lecithin - the compound that enables emulsification in recipes such as hollandaise or mayonnaise.
Some brands of egg now contain omega-3 fatty acids, depending on what the chickens have been fed (always check the box). Eggs are regarded a 'complete' source of protein as they contain all eight essential amino acids; the ones we cannot synthesise in our bodies and must obtain from our diet.
One large egg contains:
78 calories - 6.3g protein - 5.3g fat - 1.6 saturated - 212mg cholesterol
The cholesterol question
For years eggs have been considered more of a health risk than a healthy food. Since they are high in cholesterol, it was recommended that people with high cholesterol levels avoid eggs. But it turns out the cholesterol content for which they have been vilified is much lower than it was 10 years ago. This reduction has been attributed to the changes in hen feed since the BSE crisis in the 1990s. British research shows that a medium egg contains about 100mg of cholesterol, a third of the 300mg recommended daily limit. Also it is saturated fat in the diet, not dietary cholesterol that influences blood cholesterol levels the most.
If you are concerned about your cholesterol or are unsure whether it is safe for you to consume eggs please consult your GP.
Eggs are rich in several nutrients that promote heart health such as betaine and choline. During pregnancy and breast feeding, an adequate supply of choline is particularly important, since choline is essential for normal brain development. If you are eating eggs during pregnancy however, ensure you cook until the whites and yolks are solid. In traditional Chinese medicine, eggs are recommended to strengthen the blood and increase energy by enhancing digestive and kidney function.
Eggs also contain more Vitamin D than they did 10 years ago, which helps to protect bones, preventing osteoporosis and rickets. And they are filling too. Eggs for breakfast could help with weight loss as the high protein content makes us feel fuller for longer. Eggs should be included as part of a varied and balanced diet.
Quail eggs have a similar flavour to chicken eggs, but their petite size (five quail eggs are usually equal to one large chicken egg) and pretty, speckled shell have made them popular in gourmet cooking. The shells range in colour from dark brown to blue or white. Quail eggs are often hard-boiled and served with sea salt.
Duck eggs look like chicken eggs but are larger. As with chicken eggs, they are sold in sizes ranging from small to large. Duck eggs have more protein and are richer than chicken eggs, but they also have a higher fat content and more cholesterol. When boiled, the white turns bluish and the yolk turns red-orange.
How to select and store
Choose eggs from free-range or organically raised chickens. Eggs should always be visually inspected before buying. It is best to check for cracks or liquid in the box to ensure there are no broken ones. Eggs are best stored in the refrigerator where they may remain for up to one month (check the best-before-date on the box). Eggs with higher omega-3 fatty acid content are best eaten as early as possible to keep these oils fresh.
The main safety concern is risk of salmonella food poisoning. The best protection is to cook eggs at a high enough temperature for a long enough period of time, meaning poached, scrambled and hard boiled eggs carry a much lower salmonella risk. Another safety concern regarding eggs is that they are a common food allergen, particularly among young children. See your GP if you have any concerns regarding allergies to eggs. Substitutes can be used to bind ingredients together but they are not as good at helping mixtures rise. If using a replacement for eggs in baking, adding a little extra baking powder may help.