High density lipoproteins are important for the transport of cholesterol (collectively known as HDL-C) to the liver for breakdown and removal. In clinical practice, HDL cholesterol, rather than HDL particle structure or function, is used to risk stratify patients. Because these molecules transport cholesterol away from the arteries to the liver, HDL-C is commonly viewed as 'good' cholesterol and has been associated with reduced risk of coronary heart disease.
Low serum HDL-C can occur as sole lipid abnormality or, more often, in association with hypertriglyceridemia or elevated LDL particles or apolipoprotein B levels. These abnormalities are seen in people who have metabolic syndrome — a cluster of conditions that include obesity, increased blood pressure and high blood sugar levels.
Although low levels of high-density lipoprotein (HDL) cholesterol are associated with an increased risk of cardiovascular disease (CVD) events and high levels with a decreased risk, this does not mean that low HDL cholesterol causes coronary artery disease. The difficulty in demonstrating improved outcomes with therapies to raise HDL cholesterol is one argument in supporting lack of causality. Trials testing such drugs were halted early because no clinical benefit was seen in patients. So, it remains unknown whether efforts to raise HDL-cholesterol improves the risk for developing heart disease and what is the best way to do it.
HDL cholesterol is turning out to be a much more complex substance than we once believed. The absolute level may not be as important as the ‘quality’ and a deeper understanding of the genes controlling the production and the ‘quality’ of the HDL-cholesterol to perform it’s protective role is the focus of ongoing research.
If you are at increased risk for atherosclerotic ‘plaque’ (for instance, because of high blood pressure, diabetes, or smoking), or if you already have significant plaque in the arteries of your heart and brain, you should try to increase your HDL levels, if they are low. Lifestyle measures include doing regular exercise, e.g. half an hour of brisk walking, at least five days per week, maintaining a healthy weight, smoking cessation and a diet low in saturated fats.
Foods which enrich HDL cholesterol include beans and legumes, whole grains (bran, cereals, and brown or wild rice), olive oil, avocados, berries and oily fish which have a high content of omega-3 fatty acids, like salmon, mackerel, herring, lake trout, sardines, and albacore tuna.