Eating garlic, or taking garlic supplements, does not reduce cholesterol levels, researchers have found.

"Garlic supplements, many of which seek to package the benefits of raw garlic in more palatable forms, are promoted as cholesterol-lowering agents and are among the top-selling herbal supplements," explain lead researcher Dr Christopher Gardner, from Stanford University Medical School in California, USA, and his team.

To investigate the validity of these claims, the researchers studied 192 adults who had moderately high levels of cholesterol.

In total, 49 participants were assigned to eat raw garlic, 95 to take one of two types of garlic supplements and 48 to take a dummy supplement.

The amount of garlic consumed by the participants was equal to an average-sized garlic clove each day, for 6 days per week.

The participants' blood concentrations of cholesterol were measured each month over the course of the 3-year study.

By the end of the study, there were no significant changes in any of the participants' levels of 'good' or 'bad' cholesterol.

No serious side effects occurred, but around half the participants, unsurprisingly, reported suffering from bad breath or body odour.

"There were no statistically significant effects of the three forms of garlic on… cholesterol concentrations," Dr Gardner and colleagues conclude.

However, they add that garlic may have cardiovascular health benefits that were not assessed in their study.

The research is published in the Archives of Internal Medicine.