An introduction to eggs
Both the white and yolk of an egg are rich in nutrients, including proteins, vitamins and minerals. The yolk also contains cholesterol, fat-soluble vitamins (such as vitamins D and E) and essential fatty acids. Eggs are also 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, which also includes vitamin B2 and lower amounts of fat than the yolk. Eggs are rich sources of selenium, vitamin D, B6, B12 and minerals such as zinc, iron and copper. Egg yolks contain more calories and fat than the whites. They are a source of 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 as a ‘complete’ source of protein as they contain all nine essential amino acids, the ones we cannot synthesise in our bodies and must obtain from our diet.
One medium egg (boiled) contains:
- 84 calories
- 8.3g protein
- 5.7g fat
- 1.6g sat fat
Did you know?
A study published in Paediatrics magazine has suggested that giving young children just one egg a day for six months, alongside a diet with reduced sugar-sweetened foods, may help them achieve a healthy height and prevent stunting.
The cholesterol question
For years, eggs were considered more of a health risk than a healthy food. This is because they were considered a high-cholesterol food, so those with high cholesterol levels were advised to avoid them. We now know that the cholesterol found in food has much less of an effect on our blood cholesterol than the amount of saturated fat we eat. If you’ve been advised by your GP to change your diet in an attempt to reduce your blood cholesterol levels, the best thing to do is to keep to daily guideline intakes for saturated fat (20g for the average woman and 30g for the average man) opting instead for monounsaturated fats found in olive and rapeseed oils. It’s also a good idea to increase your intake of vegetables, wholegrains, lean meats and low-fat dairy while minimising sugars and refined carbs.
If you are concerned about your cholesterol or are unsure whether it is safe for you to consume eggs, please consult your GP.
Eggs for health
Eggs are rich in several nutrients that promote heart health, such as betaine and choline. A recent study of nearly half a million people in China suggests that eating one egg a day may reduce the risk of heart disease and stroke, although experts stress that eggs need to be consumed as part of a healthy lifestyle in order to be beneficial.
Eggs are a useful source of vitamin D, which helps to protect bones and prevent osteoporosis and rickets. Shop wisely, because the method of production – free range, organic or barn-raised – can make a difference to vitamin D content. Eggs should be included as part of a varied and balanced diet. They are filling, and when enjoyed for breakfast, may help with weight management as part of a weight-loss programme, as the high protein content helps us to feel fuller for longer.
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. 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 main body of the refrigerator where they may remain for up to one month (check the best-before date on the box). Eggs higher in omega-3 fatty acids are best eaten as early as possible to keep these oils fresh.
The main safety concern used to be salmonella food poisoning, but the Food Standards Agency (FSA) have recently changed their guidelines on eating runny eggs. They now say that infants, children, pregnant women and elderly people can safely eat raw or lightly cooked eggs that are produced under the British Lion Code of Practice. Visit the FSA website for more information.
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.
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This article was last reviewed on 6th November 2019 by Kerry Torrens.
Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.
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