HDL: Good and Brainy
The "good" cholesterol particle may help fend off strokes and dementia in addition to preventing heart disease, so it's time to pay it some mind.
High-density lipoprotein (HDL) is the "good" cholesterol particle. Under the right conditions, HDL scoops up cholesterol from macrophages that have infiltrated artery walls and deposits it in the liver, which then excretes the scavenged cholesterol harmlessly into the small intestine as bile salts. And HDL's benefits may go well beyond cholesterol removal. Studies suggest that it may retard inflammation, inhibit the formation of blood clots, and prevent oxidation of lipids, a central event in the artery-damaging atherosclerotic process. If HDL does all that, calling it the "good" cholesterol hardly seems adequate.
The main consequence of having high HDL levels is a lower risk of heart disease. A small but growing number of studies suggest that high levels might also ameliorate stroke and dementia risks. Late in 2007, for example, a re-analysis of data from the Vitamin Intervention for Stroke Prevention study showed that people with high HDL levels were more likely to fully recover from a mild or moderate stroke. Other studies have found that high HDL lowers people's chances of having certain kinds of strokes. And there's some interest in experimenting with HDL levels to treat strokes.
Hopes that high HDL might fend off dementia are pinned primarily on studies that have identified a correlation between low HDL levels and dementia. Of course, picking out correlations is miles away from proof of cause and effect. Still, there is some evidence that HDL may hinder the development of the beta-amyloid plaques that many experts believe are a primary cause of Alzheimer's disease.
For better or worse, statins (Lipitor, Zocor, other brands) have gotten Americans used to taking medicine to change their cholesterol levels. Drug company plans to cash in on a huge market for HDL boosters were dealt a setback in 2006 when a clinical trial of Pfizer's HDL drug, torcetrapib, was found to increase cardiovascular "events" (strokes, heart attacks, etc.) — and deaths from any cause — compared with treatment with just a statin. The experimental drug had these effects even though it increased HDL levels by 72%. It's not clear why. Torcetrapib may produce the wrong kind of HDL, or reductions in potassium levels might be to blame. Another theory is that aggressive removal of cholesterol from fat-laden plaques makes them more likely to rupture and cause heart attacks.
The chart below provides a few quick reminders of ways to increase HDL levels.
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How you can increase your HDL
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Without pills
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With pills
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Getting exercise, drinking moderate amounts of alcohol, or losing weight all ramp up HDL levels. These actions probably have some benefit for everyone, although the effect on HDL may be strongest in people who already have high levels.
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Niacin in large doses (1 to 2 grams per day) can increase HDL by 20% to 30%. Taking aspirin 30 minutes or so before niacin can prevent flushing, a sudden reddening of the skin that can be very uncomfortable. Most doctors prefer patients to take prescription niacin because it's regulated by the FDA, so there's more certainty that pills contain the amount of niacin advertised.
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Trans fat lowers HDL, so you can nudge your levels in the right direction by avoiding it. Trans fat (identifiable in ingredient lists as partially hydrogenated oil) is disappearing from the American food supply, so dodging it is getting easier.
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Fibrates (clofibrate, fenofibrate, gemfibrozil) are more effective at lowering triglycerides than raising HDL, but that makes them a good choice if you have high triglycerides (200 to 499 mg/dL) as well as low HDL (40 mg/dL or lower). Side effects are a worry: taking both a fibrate and a statin increases the risk of muscle weakness. Fenofibrate (Antara, Tricor, other brands) is the best fibrate to take with a statin.
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Some varieties of nuts increase HDL levels, presumably because of the polyunsaturated fat content. But the fat content also means that they are high in calories, so don't overdo it unless you want to gain weight.
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LDL-lowering statins also increase HDL, but the effect varies with the statin and is most pronounced at high doses. Rosuvastatin (Crestor) seems to be more effective at boosting HDL than simvastatin (Zocor), and simvastatin may be more effective than atorvastatin (Lipitor).
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The Dietary Approaches to Stop Hypertension (DASH) trial showed that an eating plan emphasizing fruits, vegetables, and low-fat dairy products can increase HDL levels. Mediterranean-style diets (large amounts of olive oil, whole grains, fruit, and vegetables) are also HDL boosters.
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Statin-niacin combinations have been shown to increase HDL by 18% to 21%, and the addition of the niacin doesn't seem to increase the risk of muscle-weakening side effects. One combination pill, Advicor (niacin and lovastatin), is already on the market.
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