For a long time, eggs have been thought to be somewhat unhealthy due to their cholesterol levels. However, for the last 5 years science has been re-testing old recommendations and beliefs about the limits for egg intake as well as testing the cholesterol message in relation not only to coronary heart disease, but also to general health and survival. Recent studies emphasize the large number of nutritional benefits one may accrue from regular egg consumption.
Eggs are a nutritional package of nutrients and other biochemical active components. They are nutrient dense, providing a wide variety of quality nutrients without having high calorie content. The protein quality of eggs is high, providing all the essential amino acids needed for human protein synthesis and about 10% of the daily protein requirements (based on a 2000 calorie diet).
Egg protein is the standard against which other food proteins are measured. Eggs are good sources of vitamin A, B1, B12, D and E as well as folate, phosphorus, zinc and iron. Eggs are one of the rare natural sources of vitamin D. Macro and micronutrients aside, another area of interest for eggs is in their antioxidant content. In comparison to green leafy vegetables, eggs contain higher levels of the carotenoid antioxidants lutein and zeaxanthin. These two compounds are believed to be protective against age related macular degeneration, a condition that occurs in individuals older than 50 and which is the leading cause of blindness in the elderly.
Eggs contain around 250-300mg cholesterol per yolk. Expert bodies like the National Heart Foundation recommend an intake of cholesterol from all sources not exceeding 300mg per day. A slice of cheese (30g) or cup of full-fat milk has about 30mg of cholesterol; 100g cooked meat about 100mg and 100g fish about 50mg. Plant foods and their products (e.g vegetable oil) do not contain cholesterol.
Cholesterol from an egg can affect blood cholesterol levels in two ways. First, there are individual differences in the way people respond to certain foods. People who have high cholesterol levels are more likely to show a greater increase for the same amount of cholesterol in food than those whose blood cholesterol levels are initially lower. Secondly, different food habits or patterns can also influence the effect of egg consumption on blood cholesterol levels. Individuals who eat eggs and have a diet that is high in saturated fat (mainly from animal foods) are more likely to elevate their cholesterol levels than people who eat eggs and have a diet that's low in saturated fat. For example, bacon and egg on toast spread with butter is going to have a greater impact on blood cholesterol levels than an omelette consumed with salad. In other words, the saturated fat content of our diet has a greater impact on our cholesterol levels than the cholesterol content of our diet. This is because the absolute quantity of fat consumed in an average diet is much greater than the amount of cholesterol consumed and because saturated fat can be converted to cholesterol in the body.
So how many eggs a week should you consume? Around 4 small eggs per week is great. For example, try to have at least one egg meal a week such as omelette or spinach/ricotta/egg parcels or vegetarian lasagna containing boiled eggs. If you have a cholesterol level less than 5mmol/l and if you have a low intake of animal fats you can have 1-2 eggs daily if you wish. If your cholesterol level is >7mmol/l or if you have diabetes or other heart disease risk factors (like hypertension or smoking) it is advisable to limit intake to 1-2 a week. Also, remember that eggs are a 'meat alternative' - this means that when you have an egg meal it counts as a 'serving of red meat' - which is great news for vegetarians.