Research has consistently shown that adequate HDL (“good”) cholesterol levels have a protective effect on people’s cardiovascular health. High HDL cholesterol levels are good because HDL has been shown to reverse some of the harmful effects of LDL (“bad”) cholesterol. Therefore, the more bad cholesterol a person has, the more HDL cholesterol is needed.
Research has not determined the necessary clinical HDL target levels to reduce the risk of heart attack and heart disease. There is a broad consensus, however, that higher HDLs are cardioprotective. The National Heart, Lung and Blood Institute considers HDL cholesterol levels of below 40 milligrams/deciliter (mg/dL) to be a risk factor for heart disease. Thus, people are frequently advised to keep HDL levels above 40 md/gL.
HDL levels above 60 mg/dL are considered a "negative risk factor" and will reduce the 10-year risk of suffering a heart attack, according to the coronary risk score designed by the Framingham Heart Study.
HDL levels are also used to help diagnose metabolic syndrome, a cluster of risk factors that is known to increase risk of heart attack. For a diagnosis of metabolic syndrome, men need to have HDLs less than 40 mg/dL, and women need to have HDLs less than 50 mg/dL, along with the presence of other risk factors including obesity, elevated triglycerides, insulin resistance and high blood pressure.
In light of research showing that women are at increased risk of heart attack after menopause, the American Heart Association encourages women to keep their HDL cholesterol level at 50 mg/dL or higher. Studies have shown that healthy HDL levels in the elderly can help preserve function of brain cells and protect against mental decline and low HDLs are linked with a higher risk of death from coronary artery disease and stroke.
There are a number of strategies for increasing the level of HDL cholesterol and taking full advantage of its protective effect.
Fats that increase HDL
Whereas saturated fat (found in butter, cheese, etc.) can increase a person's level of “bad” LDL cholesterol, monounsaturated fat can increase the level of “good” HDL cholesterol. Monounsaturated fat can also reduce levels of LDL cholesterol and triglycerides. The net effect of eating monounsaturated fat (in moderation) is a lower risk of heart disease.
Foods that contain monounsaturated fats include:
Olive oil
Other vegetable oils
Nuts (for people who are not allergic)
Avocados
The American Heart Association recommends that people consume less than 30 percent of their daily calories from any type of fat and choosing monounsaturated fat over saturated fat or trans fat is generally helpful when working to improve cholesterol levels.
Impact of triglycerides on HDL
Research has shown a strong inverse relationship between HDL cholesterol and fat in the blood called triglycerides, which have been linked to increased risk for heart attack and heart disease. If a person's triglyceride level is high, the HDL cholesterol level is usually low. If the triglyceride level is low, the HDL cholesterol level is usually high. Therefore, lowering the triglyceride level can help to improve the HDL cholesterol level.
The National Heart, Lung and Blood Institute classifies triglyceride levels as “normal” if they are below 150. Strategies for reducing triglyceride levels include:
Decrease the amount of saturated fat in the diet.
Eat a balanced, heart-healthy diet in which carbohydrates are eaten in proportion to proteins, vitamins and minerals, essential fatty acids and fiber.
Favor the complex carbohydrates over simple carbohydrates. Simple carbohydrates, such as sugar, are absorbed quickly and can cause a sudden rise in insulin production (which in turn can increase triglycerides). Complex carbohydrates include bran and oats, as well as potatoes, pasta and bread.
Limit use of alcohol. Generally, men should limit their alcohol intake to two drinks per day, while women should drink no more than one drink per day.
Start a regular exercise program.
Achieve and maintain and a healthy weight.
Control diabetes.
Control high blood pressure.
If these strategies are unsuccessful, a physician might prescribe nicotinic acid, certain fibrates (e.g., fenofibrate) or other types of cholesterol-reducing drugs.
Impact of phytosterols on HDL
Phytosterols are vegetable fats or “plant” cholesterol. They are found only in plants and have a similar chemical structure to human cholesterol. A number of studies over the past two decades have suggested that intake of phytosterols lowers LDL cholesterol levels, although scientists are still trying to understand exactly how this occurs. This discovery has led to the creation of several phytosterol-enhanced food items (usually in the form of butter alternatives) that claim to lower cholesterol levels.
One phytosterol-rich food that has received a great deal of attention is soy. Researchers have learned that soy contains chemical compounds called isoflavones, which have a significant impact on cholesterol levels. Soybeans (and flaxseed) also contain phytoestrogens, which are natural compounds that mimic the effects of estrogen in the body (e.g, raising HDL levels).
However, a woman with a personal or family history of estrogen-dependent health problems (e.g., breast cancer) should speak with her physician before consuming large amounts of phytoestrogen-rich foods such as soy – particularly if she is already taking estrogen in birth control pills or hormone replacement therapy. Also, although the benefits of foods containing soy have been well documented, other studies have shown that soy supplementation does not have the same range of benefits.
Soy products include:
Soy milk (available in regular and nonfat forms)
Chocolate made from soy milk instead of dairy milk
Tofu or textured soy as meat alternatives
Soy flour that can be used for baking
A soy version of peanut butter
Other foods in which phytosterols occur naturally include:
Sesame, corn, sunflower and canola oils
Sesame seeds
Sunflower seeds
Peanuts
Rice bran
Green peas
Other strategies for increasing HDL
In addition to the dietary strategies involving types of fats, phytosterol intake or reducing triglyceride levels, there are several other strategies that can help increase HDL cholesterol levels:
Quit smoking. Stopping smoking can dramatically increase HDL cholesterol levels.
Start a regular exercise program.
Maintain a healthy weight.
Drink alcohol in moderation (one serving daily for women or two drinks daily for men). Moderate alcohol use - especially red wine - may increase HDL cholesterol levels. However, individuals who do not drink alcohol are urged not to begin drinking for the supposed health benefits. Large quantities of alcohol have the opposite effect to moderate alcohol use and can cause damage to the heart muscle.
Increasing intake of soluble fiber. Soluble fiber (oatmeal, citrus fruits, beans) lowers LDL (bad) cholesterol and is also thought to raise HDL cholesterol. However, the American Heart Association (AHA) advises that people eat both soluble and insoluble fiber as part of a heart healthy diet.
Studies of postmenopausal women have found that calcium supplements (calcium citrate) can increase HDL levels. This effect is attributed to calcium’s effect on the introduction of saturated fats into the bloodstream. Calcium is seen to enhance the release of these fats from the body as waste products. However more research in this area is needed before calcium can be recommended to increase HDL cholesterol levels. Always check with a physician first to see whether a particular over-the-counter drug or supplement is appropriate and safe to take.
If these strategies are unsuccessful, a physician may recommend medications that have shown to raise HDL levels, such as fibrates, nicotinic acid or some other cholesterol-reducing drugs, including statins.
Recent studies of medications specifically designed to raise HDL cholesterol have been disappointing. For example, one study with a drug called torcetrapib was shown to significantly increase HDL cholesterol, but, surprising, was also associated with an increased risk of cardiovascular events.
Questions for your doctor on good cholesterol
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about increasing good cholesterol:
What are my cholesterol levels?
What should my HDL level be?
What happens if I do not have enough HDL?
How can I raise my HDL level?
Which fats are good and which are bad?
Is it possible to have too much HDL cholesterol?
How often should I have a cholesterol test?
Are there any medications that can help increase my good cholesterol?
Are there any lifestyle changes I can make to increase my good cholesterol?
