Statin drugs are credited with a significant reduction of cardiovascular disease over the past 20 years. However, even when LDL (low-density lipoprotein cholesterol) has been properly reduced, heart attacks still occur. Additional targets besides LDL-lowering must be explored, such as HDL.
HDL (high-density lipoprotein cholesterol), when elevated, is associated with a lower incidence of heart attacks, strokes and death. HDL protects the heart. Low levels of HDL are associated with higher risk of heart disease and mortality. HDL promotes the removal of excess lipid material from the arteries. Low HDL can be due to smoking and to genetic disease. Statin drugs cannot compensate for the risk resulting from low HDL. Low HDL levels help define metabolic syndrome.
The minimum level of HDL thought to be heart protective is 35 to 40 mg/dL. The desirable level for men is 40 mg/dL and for women is 50 mg/dL. Thirty-five percent of men are below 40 and 39% of women are below 50.
Lipoproteins, made of fats and proteins, are the carriers of HDL and LDL in the blood. HDL is a small structure part protein and part lipid. The lipid portion contains phospholipid, cholesterol, cholesterol esters and triglycerides.
Raising HDL levels should be a goal in the management of arteriosclerosis and a number of pharmaceutical agents are being developed for the condition. Nicotinic acid is used for isolated HDL deficiency. Smoking cessation should be promoted, as should weight management. Increased physical activity and elimination of medications known to lower HDL are beneficial, as is diabetes control.
Dietary attempts to increase HDL include reducing saturated fats intake to less than 7% of total caloric need. Total cholesterol should be less than 200 mg/day, and trans fats should be at a minimum. Polyunsaturated fats should be 10% of total energy intake, while monounsaturated fats should be 20% of total energy intake. Carbohydrates should be 50 to 60% of total energy intake, while protein intake should be 15% of total energy intake. People should consume 20 to 30 g/day of fiber.
CONCLUSION: Normalizing HDL levels is not sufficient to eliminate the risk of cardiovascular disease. Now we know that it is necessary to raise low HDL levels also. Dietary guidelines are listed above.
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