Known as the good cholesterol, it is the designation for high-density lipoprotein cholesterol.
It is the cholesterol-carrying protein in your blood that acts like arterial Drano, helping to keep critical blood vessels from clogging up with circulation-impeding deposits.
While you and your doctor may be more concerned with your total cholesterol or the amount of LDL-C. (low-density lipoprotein cholesterol, the bad cholesterol) or triglycerides in your blood, a low level of good cholesterol is the most common lipoprotein abnormality in people with cardiovascular disease.
Further, said Dr. Michael Miller, who directs the Center for Preventive Cardiology at the University of Maryland Medical Center, low levels of good cholesterol best predict the risk of having a heart attack, even if total cholesterol is normal.
High-density lipoprotein transfers cholesterol from various parts of the body to the liver, where it is excreted. The low-density type, on the other hand, is the source of cholesterol that narrows the artery walls.
Most people, women as well as men, who suffer heart attacks have HDL readings below 40 milligrams per deciliter of blood serum. In the latest version of the National Cholesterol Education Program's treatment guidelines, a reading below 40 is ranked as a risk factor in heart disease.
In fact, as Miller recently noted in The Cleveland Clinic Journal of Medicine, "Several studies have shown coronary heart disease risk to be more strongly or consistently related to HDL-C. levels than to LDL-C. levels."
Vegetarians tend to have low levels of good cholesterol, Miller said. But for anyone who consumes animal-based foods that contain cholesterol or saturated fat, the higher the good cholesterol, the better.
The average ratio of total cholesterol to good cholesterol is 4.5-1 in the United States, and among those with established heart disease it is 5.5-1, Miller said. But in the Framingham Heart Study, those who were least likely to suffer heart attacks had ratios of 3-1 or better.
Let's say your total cholesterol level is 210 milligrams per deciliter of blood serum. To achieve a ratio of 3-1, you'd need an HDL of 70. But if your total cholesterol is 150, a reading of 50 in good cholesterol will suffice, and if the total is 120, a good cholesterol level of 40 is the goal.
Strategies for raising levels of good cholesterol include medications and changes in diet and habits. Let's start with weight. Overweight or obese people are more likely to have abnormal levels of blood lipids, including low levels of good cholesterol and elevated triglyceride levels.
Once the weight is lost, Miller wrote, "There is a surge in the HDL-C. level of about 1 milligram per deciliter for every 7 pounds lost."
While there is no magic for selectively raising the good cholesterol, certain diets favor a higher level. Interestingly, one of them is not low-fat. If you merely reduce dietary fat and replace it with carbohydrates without also reducing the number of calories consumed, levels of good cholesterol may fall as much as 20 percent, Miller noted.
But the kind of fats consumed can make a difference. Evidence indicates that foods rich in monounsaturated fats like canola and olive oil, most nuts and avocados can improve levels of good cholesterol without raising the total.
Polyunsaturates like corn, safflower and soybean oils tend to lower the levels of both the good and the bad.
Miller favors a Mediterranean-style diet with 30 to 35 percent of calories coming from fat. It consists of lots of vegetables and fruits, nuts and fish but little meat or high-fat dairy products. The best fish are the fatty ones, rich in omega-3 fatty acids, like Atlantic salmon and mackerel.
Even more important than diet to raising good cholesterol, however, is regular aerobic exercise, and the benefit, Miller says, is "dose-related."
In other words, the more aerobic exercise one does, the higher good cholesterol is likely to be. Those who are not star athletes will be pleased to know that duration, not intensity, is most beneficial.
Drugs can help, too, if diet and exercise are not enough. B vitamin niacin has the most potent effect on good cholesterol, Miller said, raising it as much as 30 percent. It is best taken with food and in extended-release preparations.
Statins, now the most popular heart-protective drugs, have a modest effect on good cholesterol, raising it by about 5 to 10 percent. The fibrates gemfibrozil (Lopid) and fenofibrate (Tricor) can raise good cholesterol 5 to 20 percent.
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