Dietary cholesterol: Does an egg a day bring the doctor today?
It seems that nowadays all the attention concerning diet and heart disease risk centers around the consumption of fat and their effects on cholesterol levels. We know that saturated and trans fats are bad while unsaturated fats can be good for your cholesterol. Whatever happened to the relationship between eating cholesterol and your blood cholesterol level? Doesn't it seem logical that the more cholesterol you eat, the higher your blood level will be and therefore the higher your risk of a heart attack? And if so, how come we hear so much more about fat consumption and not so much about cholesterol consumption? The answers to some of these questions will seem very straightforward, but the relationship between dietary and blood cholesterol is not that simple.
Dietary cholesterol and blood cholesterol are two different types of cholesterol. Dietary cholesterol is found exclusively in animal products such as red meat, poultry, fish, eggs, and dairy products. Often times, foods high in fats will have high amounts of cholesterol such as red meat, but some foods such as nuts that are also high in fat have no cholesterol at all. Blood cholesterol is mainly produced by the liver. In fact, about ¾ of your blood cholesterol is manufactured by the liver while only ¼ is absorbed from food. Blood cholesterol is a waxy-like substance that cannot move freely throughout the body. It has to be carried in protein packages called lipoproteins. Low density lipoproteins (LDL) are the bad protein packages that carry cholesterol from the liver to the rest of the body. High levels of LDL can lead to cholesterol accumulation in arteries and subsequent heart disease. High density lipoproteins (HDL) are the good protein packages that carry cholesterol from the body to the liver where the cholesterol can then be removed from the blood. Cholesterol is an essential component of our bodies as it is crucial in the production of certain hormones, vitamins, and cell membranes.
So, is eating lots of cholesterol bad for your blood cholesterol level? The answer, not surprisingly, is yes. However, because only ¼ of your blood cholesterol is absorbed from food, the effect of dietary cholesterol on blood cholesterol is minor. And therefore, the effect of dietary cholesterol on the risk of a heart attack is also only minor at best. Studies have shown that if you increase your daily cholesterol consumption 200-400mg/day (equivalent to eating one extra egg/day), there is no significant increase in a heart attack. Remember a few years back when eggs were given such a bad rap as the cause of numerous heart attacks? Today, the restrictions of eggs in the diet have been markedly relaxed. Eggs can become a part of a heart healthy diet if consumed in moderation. They are also a great source of protein and contain vitamins such as B12 and folate that may even reduce the risk of a heart attack.
So why is it that we hear much more about fat as opposed to cholesterol consumption when talking about blood cholesterol levels? Because total fat and the type of fat consumed have a much greater impact on blood cholesterol and subsequent heart disease risk than dietary cholesterol. Not to say that dietary cholesterol is not important, but when compared to the effects of dietary fat on blood cholesterol, dietary cholesterol takes a back seat.