The egg is a remarkable achievement of nature. It contains everything needed to make a chicken, and has long been considered one of the healthiest foods available.
Nutritionally, eggs are a very good source of protein and the trace mineral selenium, a good source of phosphorus, riboflavin and vitamin B12 and high in nutrients important for the eyes and brain, but high in saturated fat and very high in cholesterol.
In fact, a single medium-sized egg contains 62 per cent of the recommended maximum daily intake. After many years of criticism and bad publicity, eggs are again accepted in nutritional circles, and it is generally agreed that up to 3 whole eggs can be safely eaten each day, and 2 to 6 of the cholesterol-rich yolks a week.
What if you want to eat more than 3 eggs a day, and more than 6 yolks a week?
An 88-year-old man who had eaten 20 to 30 soft-boiled eggs a day for at least 15 years was reported in 1991 (1). He reported no adverse effects from eating the eggs throughout the day, had kept careful records of the eggs consumed and was thought to have done this because of a psychological compulsion.
Whatever the reason for this remarkable record of egg-eating, his health was excellent and his cholesterol level was normal and had been so for years.
Eating more than the recommended number of eggs and egg yolks apparently caused him no problems, and there is in fact little evidence to support any restriction of egg eating on account of cholesterol content.
Related: An EGG-ceptional Superfood Backed by Science
The Truth Behind The Cholesterol Myth
Cholesterol is associated in most people’s minds with heart attack and stroke, but it is an important part of the cell membrane, and of the sheath that surrounds nerve fibers and allows them to conduct electricity.
Cholesterol is also necessary for the production of the adrenal gland hormones cortisol and aldosterone, and of the sex hormones estrogen and testosterone. It is made into bile in the liver and may protect other cells as an antioxidant.
A certain amount of cholesterol is necessary, and it is produced in the liver if it cannot be obtained in the diet.
If cholesterol is taken in from eggs and other foods, production by the liver is dialed back or shut down [2], so that the total amount of cholesterol obtained from diet and produced by the liver stays about the same(3).
This has led to the suggestion that the recommended limitation of cholesterol intake, from eggs and otherwise, should be reconsidered(4).
HDL Vs. LDL Cholesterol
There is more to cholesterol than just the blood level, however. There are several different subtypes of cholesterol, mainly HDL (high-density lipoprotein) LDL (low-density lipoprotein).
- LDL is the “bad” cholesterol that contributes to atherosclerosis, the deposition of fats and calcium in blood vessel walls that leads to their blockage and results in heart attack and stroke.
- HDL is the “good” cholesterol that helps to remove these deposits and has a protective effect against heart attack and stroke(5).
Several large studies have confirmed that the “good” HDL cholesterol is increased with egg consumption(6), that eggs increase the beneficial effect on “good” cholesterol of a restricted-carbohydrate diet(7) and that whole eggs are more effective in raising “good” cholesterol levels than egg whites(8).
LDL Subtype Cholesterol
Total cholesterol levels generally do not change with egg consumption(9), but there is sometimes an increase in LDL cholesterol(10).
About 30 per cent of people respond to eating whole eggs with a slight increase in LDL cholesterol, but there is no association between egg consumption and heart disease(11).
This is apparently because small dense LDL particles are the ones associated with heart and blood vessel disease, and larger LDL particles are not necessarily “bad” cholesterol.
The rise in LDL cholesterol in some people who consume eggs is due to an increase in the large LDL subtype(12), and this kind of cholesterol is not associated with the risk of heart attack and stroke(13).
High cholesterol and excessive “bad” LDL cholesterol is often combined with depletion of insulin and the development of elevated blood sugar, and eventually of diabetes.
The combination of central obesity, the apple or pear shape that is characteristic of overweight men, high blood pressure, decreased HDL and increased LDL cholesterol and resistance to the effects of insulin was first recognized in the 1950s and has been called syndrome X, insulin resistance syndrome, cardiometabolic syndrome and CHAOS (coronary artery disease, hypertension, atherosclerosis, obesity, stroke) syndrome.
The term metabolic syndrome is now generally applied, and the condition now affects about one-third of the U.S. population and is increasing(14).
Eggs and Diabetes
There has been some concern about the effects of eggs in people with diabetes.
A number of studies, some of them very large, have shown that people who eat eggs do not have an increased risk of heart disease or stroke(15).
In some studies the risk of stroke is actually lower with egg consumption(16).
The risk of heart disease is greater in diabetics who eat eggs, however, although it is not clear in these studies whether this is due to the eggs or to other factors like diet, exercise or severity of the diabetes(17).
If people with diabetes follow a low-carbohydrate diet, eating eggs is associated with a decrease in risk factors for heart disease(18) and improvement of the metabolic syndrome(19).
Eggs have several other health benefits. They are rich in the antioxidants lutein and zeaxanthin, which reduce the risk of cataracts and macular degeneration, the leading causes of visual loss with aging(20).
They also supply choline, a brain nutrient and precursor of the memory neurotransmitter acetylcholine, which may be deficient in the diet of as many as 90 per cent of people in the United States (21).
Eggs are a rich source of high-quality protein, which is increasingly important with age in maintaining bone health (22) and muscle mass(23).
They have also been shown to increase satiety and facilitate weight loss with dieting(24), and to enhance the loss of body fat(25).
How many eggs a day can you safely eat? Apparently, as many as you want, if you pay attention to your total calorie intake and are careful about carbohydrate intake.
If you have diabetes, you can safely eat eggs too, but will need to be particularly attentive to carbohydrates and blood sugar control.