Eggs, cholesterol and heart disease
~ March 2013 No.247 ~
For many, the question has not been "Which came first, the chicken or the egg?" but rather "If I am worried about heart disease, should I stop eating eggs?" Eggs are a very popular food item, and so there has been much concern for those wanting to eat healthier. The relation between egg consumption and heart health has recently been reviewed and the conclusion is good news for those who were worried.
As a food, eggs are an inexpensive source of protein and minerals. When compared to other protein sources, the cost of eggs is relatively low and has remained stable over time. Eggs, depending on how they are cooked, are also relatively low in calories. But yes, one large egg contains about 210 mg of cholesterol, making eggs one of the chief sources of cholesterol in many people's diets. Other foods high in cholesterol include shrimp, liver, kidney, and caviar. However, a fact that is often forgotten is that, for most people, dietary sources of cholesterol supply only a small part of the amount of cholesterol our bodies need to function. Our liver is actually the main source of cholesterol that is circulating in the blood. Cholesterol is found in every cell in the body; cholesterol contributes to cell membrane permeability and is also a building block included in some hormones, bile acids and vitamin D. Our bodies need cholesterol, but not too much.
High serum cholesterol has been shown to be a risk factor for cardiovascular disease. Many scientific studies have been published that show this. As a result, one of the most common blood tests that is given to people during their annual medical check-up is a measure of their blood cholesterol levels. As with many things, the cholesterol story is a little bit more complicated. It turns out that there are several types of cholesterol in our bodies, and not all cholesterol is "bad." Today we can measure total cholesterol, and several fractions such as LDL often referred to as bad cholesterol and HDL which is called good cholesterol. People with "cholesterol problems" want to reduce their blood total cholesterol levels, lower their LDL cholesterol levels, and maintain or raise their HDL levels. This can be done with drugs, changes in the diet, and changes to lifestyle (smoking, exercise). So, should eggs be targeted, if cholesterol and cardiovascular disease are concerns?
In a recent paper that reviewed eight previously published articles describing nine studies of coronary heart disease (using 3,081,269 person years of data) and eight studies looking at stroke (4,148,095 person years of data), the researchers concluded that "higher consumption of eggs (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke." The research team did caution that "increased risk of coronary heart disease among diabetic patients and reduced risk of hemorrhagic stroke associated with higher egg consumption in subgroup analyses warrant further studies."
These results should reassure most people that they can continue eating eggs.
Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies