Q: "We've been told for years that raising HDL – the 'good' cholesterol – protects against heart disease. Now a large study published in The Lancet in May seems to cast doubt on this longstanding belief. Will this change the recommendations for those of us who are trying to minimize our heart risks?"
Answer provided by Melike Arslan, M.D., FACC, interventional cardiology, Providence Medical Group-Cardiology, Medford
The study has definitely created some buzz, but don't put a halt to your heart-healthy habits just yet. Multiple studies and decades of experience have shown a clear association between higher levels of HDL cholesterol and lower risk of heart disease. I would not dismiss the beneficial effects of HDL based on this single study.
We know that HDL plays several protective roles against cardiovascular disease. For one, it removes excess cholesterol from cells, including those that form the blood vessel walls. Removing this excess cholesterol is important, because when too much LDL ("bad") cholesterol builds up in the vessel walls, it can lead to atherosclerosis – vessels that become narrowed or blocked by fatty plaques. Atherosclerosis is the leading cause of heart attacks and strokes.
HDL also protects against inflammation, has antioxidant properties, helps to maintain vascular health, and has other properties that protect against atherosclerosis. For all of these reasons, we know that higher levels of HDL are associated with lower cardiovascular risk – and multiple studies have backed that up. The very famous Framingham Heart Study, for example, found that the risk of heart attack goes up when HDL levels go down. Numerous population studies also show that low HDL is more common in people who have premature coronary heart disease than in healthy people.
So how is this new study different? Acknowledging the association between high HDL and reduced heart attack risk, the researchers hoped to shed light on whether or not it is HDL, specifically, that reduces risks. The study looked at several gene variants that are associated with higher HDL levels, expecting to find that people with these genetic tendencies toward higher HDL would have lower heart risks. Surprisingly, the study showed that these people had no added protection against heart attack than the general population.
So what does this mean? It does raise the possibility that HDL is more of a marker of good heart health, rather than a protective factor in and of itself. But keep in mind that this is just one study of a few genetic markers. There are many other genes, and many other factors, that affect HDL and a person's cardiovascular risks. The one thing this study does make clear is that we still have a lot to learn about HDL.
If having genetically high HDL makes no difference in a person's heart risks, does that mean that taking medication aimed at raising HDL is unnecessary? It depends. A drug designed solely to raise HDL may be of questionable benefit. However, there are very few drugs like this, because we rarely aim to treat low HDL alone. Treatment generally focuses on other risk factors as well, which often include elevated triglycerides and LDL. Since most medications do provide other important heart benefits, it would be premature to dismiss them as ineffective. Ongoing studies continue to investigate this question.
What we do know, without doubt, is that there are numerous actions you can take that will both lower your cardiovascular risk and raise your HDL. Here are a few:
- Exercise regularly.
- Eat a healthy diet that minimizes red meat and saturated fat and maximizes vegetables, fruits and fish.
- If you are carrying extra pounds, lose weight.
- If you smoke, quit.
- Get to know your cholesterol, blood pressure and blood sugar numbers, and ask your physician what you can do to keep them within the healthy ranges.
As this study hints, good genes may not be enough to reduce your risk. So for goodness sake, keep up those behaviors that are earning the high marks.
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