Cholesterol is a waxy substance that plays an important role in the synthesis of hormones known as steroids, cell membranes and bile acids. Some forms of cholesterol can also increase your risk of developing cardiovascular problems. Conversely, other forms of cholesterol, including high-density lipoprotein, or HDL, can reduce your risk of developing cardiovascular problems.
Lipoproteins and Atherosclerosis
When cholesterol is present in the blood, it is combined with some proteins to form a complex known as a lipoprotein. One kind of lipoprotein, known as low-density lipoprotein, can promote atherosclerosis. Atherosclerosis is a condition in which cholesterol builds up in the walls of the arteries, making the arteries narrow and stiff. This can raise your blood pressure and reduce blood flow to your heart and brain. High-density lipoprotein, or HDL molecules, on the other hand, can prevent atherosclerosis by transporting cholesterol out of the blood back to the liver.
Genetics
One of the biggest determinants of your HDL levels are your genes, DiabetesHealth.com explains. The different kinds of lipoproteins are made of different proteins, so your lipoprotein levels are controlled, in part, by the amount of the different proteins your body makes. Genetics can strongly influence the amount of proteins your body makes, so if you have a family history of heart disease or low high-density lipoprotein levels, you are more likely to have low HDL levels yourself.
Diet
The foods you eat can also have a strong impact on your HDL levels. According to Go Ask Alice at Columbia University, a diet that is high in sugars and other carbohydrates can lead to low HDL levels. A high-carbohydrate diet can raise the levels of another type of fat, known as triglycerides, that can suppress HDL levels. In addition, a 2000 paper in the British Journal of Nutrition titled "Decreasing Dietary Fat Saturation Lowers HDL-Cholesterol and Increases Hepatic HDL Binding in Hamsters" found that eating lots of saturated fat could lower your HDL levels.
Weight and Exercise
Being overweight can also cause your HDL levels to be too low. If you have extra body fat, your triglyceride levels may be high, which will decrease your HDL levels. Not getting enough exercise can also depress your HDL levels, the American Heart Association explains. Thus, by cutting calories and getting more exercise, you can raise your high-density lipoprotein levels and lower your risk of having a heart attack or stroke.
