Many people have been eating garlic or taking garlic supplements and even eating raw garlic cloves because this aromatic bulb has been widely touted to lower total and LDL cholesterol. In fact, garlic is one of the top-selling dietary supplements in this country.

Poorly designed studies had found that garlic supplements did lower LDL cholesterol. However, two small but rigorous studies published in 1998 convinced me that neither garlic oil nor garlic powder supplements improved blood lipid or lipoprotein levels. As might be expected, proponents of garlic argued that the studies did not use the right type of garlic supplements and so the promotions have continued.

One advertisement presently on the Web begins with the statement: “Attention all high cholesterol sufferers! Garlic to lower [my italics] cholesterol!” — a craftily worded statement that misleads people into thinking that the supplements being sold are proven to lower cholesterol.

Now the largest garlic clinical trial to date, conducted by researchers at Stanford University, has found that neither raw garlic nor garlic tablets improved lipid levels when compared with placebo.

At the end of the six-month trial of 192 men and women with cholesterol levels between 130 and 190 mg/dL, no significant declines were detected in triglycerides or in total and LDL cholesterol; nor were levels of protective HDL cholesterol increased. Although garlic produced no serious adverse effects, 57 percent of those in the raw-garlic group noted bad breath and body odor.

The study authors cautiously pointed out that their findings could not be generalized to include people with higher cholesterol levels and that we don’t yet know whether garlic provides other cardiovascular benefits.

I agree with the authors’ conclusions: Physicians should advise patients with moderately elevated LDL cholesterol that garlic is unlikely to lower their cholesterol or produce other lipid benefits. And I would add that patients should stop wasting their money by purchasing garlic supplements.

It’s still possible, of course, that garlic — just like cauliflower or any other food — may somehow prevent cardiovascular disease, but that possibility hardly justifies taking garlic supplements until some clinical study shows conclusively that they do prevent cardiovascular disease or heart attacks.