Dietary supplements for cholesterol: Are any worth a try?

Various herbs and other supplements have been touted for their ability to improve cholesterol levels. Here's what the research shows — and doesn't show — about some of the best-known products.

Hawthorne. The leaves, berries, and flowers of this plant are used to make medicine that was traditionally used to treat cardiovascular diseases. It may lower cholesterol by increasing the excretion of bile and decreasing the body's production of cholesterol. Verdict: It may possibly help.

Red yeast rice. This Chinese medicine has been marketed in the United States as a supplement that's said to lower cholesterol levels. Some red yeast rice products contain a chemical that's identical to the active ingredient in the cholesterol-lowering drug lovastatin. But an independent analysis of 12 red yeast rice products found that although all claimed to have 600 milligrams (mg) of the active ingredient in each capsule, the actual content varied between 0.1 mg and 10.9 mg. In addition, one-third of the products were contaminated with a potentially toxic compound called citrinin, which can cause kidney failure. This cautionary tale illustrates the potential pitfalls of taking dietary supplements, which are virtually free of the testing and manufacturing requirements that apply to pharmaceutical drugs. Verdict: It may possibly help, but purity remains a problem.

Garlic. Some preliminary studies suggested that garlic might lower blood cholesterol levels slightly. But one study on the safety and effectiveness of three garlic preparations (fresh garlic, dried powdered garlic tablets, and aged garlic extract tablets) found no effect on cholesterol levels. Verdict: Save your money.

Fish oil. Oil from fatty fish such as salmon and sardines contains omega-3 fatty acids. Omega-3s have several heart-healthy effects: they lower heart rate and blood pressure and improve the health of blood vessels. Several studies have shown that eating fatty fish lowers heart risks for people with heart failure or a previous heart attack. Fish oil supplements alone might not have the same impact, however. A 2013 study in The New England Journal of Medicine found that fish oil supplements don't lower heart attack or stroke risk in people at high risk of heart disease. High doses of fish oil can lower triglycerides, but at the same time, they cause a small increase in LDL (the "bad" cholesterol). Verdict: Eat fish instead.

To learn more about the use of supplements for improving cholesterol levels, their effectiveness, and how they affect you, buy Managing Your Cholesterol, a Special Health Report from Harvard Medical School.