When it comes to HDL cholesterol, high numbers are usually the goal. HDL is the "good" type of cholesterol that sweeps the "bad" artery-clogging LDL cholesterol out of your blood vessels and to your liver. Your liver then breaks it down and removes it from your body.
How much of this good cholesterol do you need then? Health experts say that men should aim for an HDL level of 40 to 60 milligrams (mg) per deciliter (dL), and women should aim for 50 to 60 mg/dL to protect against heart disease and stroke.
If having high HDL is good, are higher numbers even better?
Not necessarily. When it comes to HDL cholesterol, you can have too much of a good thing.
How High Is Too High?
Very high HDL cholesterol levels not only don't protect you more, but they might be harmful. In one study, people who had HDL cholesterol levels above 60 mg/dL were nearly 50% more likely to have a heart attack or die from heart disease than people whose HDL levels were between 41 and 60 mg/dL.
Why might higher HDL levels be harmful? Researchers don't know for sure, but they have some ideas.
Very high HDL levels could slow the process of clearing LDL cholesterol from your arteries. When LDL cholesterol builds up in these blood vessels, it forms clumps called plaques that slow or block blood flow. Eventually a chunk of plaque can break free and form a clot, which could lead to a heart attack or stroke.
What Causes High HDL Levels?
A few things can push your HDL level above 60 mg/dL. You can control some of these factors. Others you can’t.
Your genes. Certain genes make you more likely to have high HDL cholesterol. Inherited high HDL sometimes protects against heart disease, but sometimes it increases the risk.
For example, people with a change in the gene SCARB1 have larger than normal HDL cholesterol particles in their blood that increase their heart disease risk.
Some people of Japanese descent inherit genes that make them produce too little of the protein CETP, which helps carry cholesterol around the body. Having low CETP leads to high HDL levels in your blood, but it doesn't seem to increase the risk for heart disease.
If you have high HDL and close relatives like your parents or siblings have had heart disease, a heart attack, or a stroke, your doctor might send you to a genetic counselor or cardiologist for more testing.
Your diet. Foods that are high in unsaturated fats, such as fish, nuts, and green leafy vegetables raise HDL in a good way. Other foods increase HDL cholesterol too much. They are some of the same foods that also raise unhealthy LDL cholesterol, like:
- Red meat
- Cream and other full-fat dairy products
- Cookies, cakes, and other baked goods
- Fried foods
Drinking too much alcohol can also raise HDL levels.
Medications. Medicines like these can increase HDL levels:
- Statin drugs and other medications you take to lower LDL cholesterol and triglycerides
- Birth control pills
- Hormone replacement therapy for menopause
- Drugs to prevent seizures
Menopause. While “the change” doesn’t cause a spike in HDL, it does make this good cholesterol less good. Early in life, women tend to have higher HDL than men, which protects them from heart disease. The female hormone, estrogen, seems to boost HDL levels. Lower estrogen levels after menopause change the way HDL cholesterol works in the body, making it less protective against heart disease.
Thyroid problems. Thyroid hormones help your body make and break down cholesterol. People whose thyroid gland is underactive, a condition called hypothyroidism, have higher levels of both HDL and LDL cholesterol.
Treating High HDL Cholesterol
If you don't have any symptoms or other heart disease risks, you might not need any treatment for high HDL cholesterol. You may be able to lower your HDL by drinking less alcohol and eating a low-fat diet. It might also help to change your medication if you take a statin or another drug that raises HDL levels.
Stay on top of your cholesterol levels with regular blood tests. Ask your doctor how often you need cholesterol screening based on your risks.