Though garlic is touted for heart health, new research suggests that garlic supplements have no effect on several heart disease risk factors.

In a study of 90 overweight smokers, European researchers found that those who took a garlic powder supplement for three months showed no changes in their cholesterol levels or several other markers of heart disease risk.

The study, published in the American Journal of Clinical Nutrition, adds to the conflicting evidence on garlic and heart health. A number of studies have found that garlic supplements may help lower blood cholesterol, and possibly blood pressure, but other studies have failed to find such benefits.

In the new study, researchers looked at whether a garlic supplement could affect heart risk factors other than the usual suspects of high cholesterol and high blood pressure.

Along with blood cholesterol, they measured participants' levels of C-reactive protein (CRP) and other blood proteins that indicate the degree of inflammation in the arteries. They also measured several blood substances that reflect how well the blood vessel walls are working.

Both of these factors -- inflammation and blood vessel function -- are believed to be key in heart disease risk. However, the study found that garlic may have no effect on them.

After three months, men and women who were assigned to take the garlic supplement showed no changes in either these measures or their cholesterol levels. In contrast, those given the cholesterol drug atorvastatin (Lipitor) showed a drop not only in cholesterol, but also in levels of CRP and another inflammation marker called TNF-alpha.

This makes it "unlikely" that garlic can protect the heart by combating high cholesterol or inflammation, write the researchers, led by Dr. Martijn B.A. van Doorn of the Center for Human Drug Research in Leiden, the Netherlands.  

Of the 90 adults they followed, a third were randomly assigned to take 2 grams of the garlic supplement each day. Another third took 40 milligrams of Lipitor per day, and the rest were given inactive placebo pills.

Compared with the placebo group, the Lipitor group had, on average, a 53 percent drop in "bad" LDL cholesterol, a 20 percent dip in CRP levels and a 42 percent decline in TNF-alpha. In contrast, the garlic group showed no clear differences from the placebo group, the study found.

The findings, van Doorn's team concludes, suggest that garlic powder -- and probably garlic in general -- "has no relevant place" in preventing or treating high cholesterol or the inflammation that marks artery damage.

SOURCE: American Journal of Clinical Nutrition, December 2006.