Cholesterol describes a waxy fat-like substance found in cells and the blood. Although you usually hear that you should keep your cholesterol low, the body needs some cholesterol in order to function. In fact, the cells in the body produce about 75 percent of the cholesterol in the body with the other 25 percent ingested in foods, according to the American Heart Association. The body also requires dietary protein, a type of food that provides the body with energy. Some sources of dietary protein may cause an increase in cholesterol levels.
Cholesterol
Since cholesterol is a fatty substance, it cannot flow through the blood, made mostly of water, on its own. It therefore binds to specialized proteins known as lipoproteins. Two different proteins bind cholesterol; low-density lipoprotein, or LDL, and high-density lipoprotein known as HDL. The two types together make up the total cholesterol in the body. To maintain healthy blood vessels and a healthy heart, you should keep your total cholesterol at 200 mg/dL or less.
LDL
LDL binds the majority of cholesterol in the body and it remains in the bloodstream. As cholesterol levels increase, the amount in the blood increases, allowing it to accumulate along the walls of the blood vessels. The buildup of cholesterol forms a substance known as plaque that restricts the flow of blood and increases the risk of heart disease. Because of this, doctors refer to LDL as the "bad" cholesterol. The Heart Lung and Blood Institute recommends that for optimal health, to keep LDL cholesterol levels at less than 100 mg/dL.
HDL
HDL cholesterol functions very differently from LDL. HDL binds to LDL cholesterol and carries it to the liver, which breaks it down to be excreted from the body. Doctors therefore refer to HDL as the "good" cholesterol and encourage you to increase HDL levels as much as possible. HDL levels less than 40 mg/dL increases the risk for heart disease and you should strive to get your HDL levels to above 60 mg/dL, which can protect against heart disease.
Animal Protein
Animal-derived foods, such as meat and dairy, serve as some of the best sources of dietary protein. A 6 oz porterhouse steak provides 38 g of protein, close to the recommended daily intake of protein that the Institute of Medicine Food and Nutrition Board lists as 46 g for adult women and 56 g for adult men. That same piece of meat, however, also contains 44 g of total fat, with16 g classified as saturated fat. Because saturated fat contributes to increasing blood cholesterol, specifically increasing LDL levels, the AHA recommends consuming less than 7 percent of total calories in saturated fats.
Low-Fat Protein
To maintain a heart healthy diet that lowers LDL cholesterol levels and increases HDL cholesterol levels, choose low-fat sources of proteins. Choosing fish over red meat decreases the fat intake while still providing protein. In addition, fish contains omega-3 fatty acids, which the University of Maryland reports may help to increase HDL levels. Choosing low-fat dairy products also helps to lower cholesterol levels while still serving as a good protein source. Some vegetable foods naturally low in fat also contain protein, including dried peas and beans, nuts and whole grains.
References
- American Heart Association: About Cholesterol
- National Heart Lung and Blood Institute: High Blood Cholesterol
- American Heart Association: Know Your Fats
- Institutes of Medicine Food and Nutrition Board: Dietary Reference Intakes
- University of Maryland Medical Center: Omega-3 Fatty Acids
- Harvard School of Public Health: Protein
