Because cholesterol and certain types of fat in the diet raise levels of fat in the blood, and high blood fat levels may raise the risk of coronary heart disease, the U.S. Department of Agriculture's Dietary Guidelines for Americans set a limit on the amount of cholesterol healthy people should get from their diet each day.
Significance
Dietary cholesterol is just one factor that may contribute to the development of clogged arteries that can lead to heart disease or stroke, but it is one people can control by limiting the amount of cholesterol-containing foods they include in their diets. Cutting back on cholesterol means cutting back on animal foods that are high in total fat and saturated fat, which are also associated with raised cholesterol, especially damaging forms of low-density lipoproteins, LDL cholesterol, in the blood.
Limits
One of the key recommendations of the Dietary Guidelines for Americans is for healthy people to consume no more than 300mg of cholesterol each day. For people who have heart disease, or those with LDL cholesterol levels higher than 100mg/dL, the American Heart Association recommends limiting dietary cholesterol to less than 200mg each day.
Sources
Cholesterol is only found in animal foods, such as meat, poultry, eggs, milk and dairy products. Although fat and cholesterol occur separately in food, the lower the fat content of the food, especially in the case of dairy foods, the less cholesterol it contains. For example, 1 cup of whole milk contains 33mg of cholesterol, and 1 cup of skim milk contains only 4mg. The differences in cholesterol levels in leaner cuts of meat compared to fattier cuts are not as dramatic. For instance, 3 1/2 oz. of beef short ribs contain 94mg of cholesterol, while 3 1/2 oz. of beef sirloin, which is much lower in fat, still contains 89mg of cholesterol. Some foods that are very low in fat, such as shrimp and squid, each of which contain only 1g of fat in a 3 1/2-oz. serving, are especially high in cholesterol. A serving of shrimp contains 194mg of cholesterol and a serving of squid contains 231mg.
Considerations
Dietary cholesterol does not have a huge effect on blood cholesterol levels in most people, according to Harvard School of Public Health. A subset of patients known to clinicians as "cholesterol responders" do experience sharp rises and falls in their blood cholesterol in relation to food, however, and these people have to be more careful about how many grams of cholesterol they consume in a day.
Theories/Speculation
A review of clinical studies and available data pertaining to the association between cholesterol in the diet and risk of coronary heart disease was published in an August 2010 issue of "Current Atherosclerosis Reports." The reviewers suggest that the guidelines limiting cholesterol to 300mg/day should be revised because there is no real evidence that dietary cholesterol increases the risk of heart disease. They point out that the presence of dietary cholesterol in the blood increases the amount of protective high-density lipoprotein, HDL particles, which helps maintain a healthy ratio of LDL-to-HDL cholesterol. In addition, dietary cholesterol reduces the levels of specific type of LDL particles in the blood that do increase the risk of cardiovascular disease.
References
- U.S. Department of Agriculture: Dietary Guidelines for American 2005
- American Heart Association: Know Your Fats
- Harvard School of Public Health: Fats and Cholesterol--Cholesterol in Food
- University of California Medical Center: Cholesterol Content of Foods
- "Current Atherosclerosis Reports"; Revisiting Dietary Cholesterol Recommendations--Does the Evidence Support a Limit of 300 mg/d?; M.L. Fernandez, M. Calle; Aug. 2010
