Ask Doctor K: Niacin out of favor treating cholesterol

DEAR DOCTOR K: For years I’ve taken niacin to raise my HDL cholesterol. Now my doctor wants me to stop. Why?

DEAR READER: When we talk about cholesterol, we’re generally referring to low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol.

LDL is also known as “bad” cholesterol. When there is more LDL than necessary in the bloodstream, the LDL cholesterol burrows inside blood vessel walls. It slowly forms plaques of atherosclerosis. When those plaques rupture and block blood flow, they cause heart attacks and strokes.

Sixty years ago, drugs to lower cholesterol were introduced. One of these was niacin – also called vitamin B3. Niacin slightly lowered LDL cholesterol, but tended to raise HDL cholesterol (also known as “good” cholesterol). HDL cholesterol removes cholesterol from artery walls. People with higher levels of HDL in the blood have a lower risk of heart disease.

Once statins came along, they became the first-choice treatment to lower LDL. They are much more potent in lowering LDL cholesterol than niacin. But doctors continued to prescribe niacin to raise HDL in people with low HDL levels. The idea was that raising HDL could ward off heart attacks and strokes.

It was a very reasonable theory but has fallen out of favor.

First, several recent studies have shown that raising HDL by taking niacin does not protect patients from heart attack or stroke. Even worse, we are learning that niacin also has many risks.

A rapidly absorbed and metabolized form of niacin is called crystalline niacin. It must be taken two or three times a day. This form may cause itching, facial flushing and headaches. It may also trigger gout or cause gastrointestinal bleeding or liver damage. Finally, it may trigger diabetes in people who have borderline-high blood sugar.

Niacin is still useful as an add-on therapy in people whose LDL is not lowered enough by statins alone. And it is a good alternative when statins are not effective.