CHICAGO – Garlic doesn't do much for the breath and it stinks for lowering cholesterol. That's the conclusion of the most rigorous, head-to-head study of raw garlic and popular garlic supplements, despite promoters' claims to the contrary.
Whether it was eaten raw in heart-healthy sandwiches, or in pills made of powdered or aged garlic, the strong-smelling herb had no effect on cholesterol in people whose levels were already elevated, the government-funded study found.
"If garlic was going to have a chance to work, it would have worked in this study," said researcher Christopher Gardner. But it didn't.
Garlic is a longtime folk remedy for a variety of ills, including heart disease, cancer, infections and even mosquito bites. Scientific research on its purported benefits has had conflicting results. Some previous studies suggested garlic might help lower risks for digestive and prostate cancers, or might reduce blood pressure and cholesterol levels; others found no benefit.
Health benefits have been thought to come from a sulfur-containing substance called allicin that is released when raw garlic is chopped or crushed. In lab tests, it can be applied directly to cells and has been shown to prevent cholesterol production.
But any direct benefits to the body from allicin may be diluted when garlic is eaten, said Gardner, an assistant professor of medicine at Stanford University.
Still, Gardner, a garlic lover, was optimistic when he and colleagues began their study. He called the results disappointing but said it's still possible garlic might improve cholesterol when eaten in bigger doses or by people with more severe cholesterol problems. Also, garlic could have characteristics other than influencing cholesterol that might benefit the heart, he said.
The study appears in Monday's Archives of Internal Medicine.
An Archives editorial agreed and said "the jury is still out" on whether garlic might prevent cardiovascular disease.
The study involved 192 adults aged about 50 on average with moderately elevated levels of LDL cholesterol, the bad kind that contributes to heart disease. The average LDL level was 140 milligrams per deciliter of blood, or in the borderline-high range. Below 100 is considered ideal.
Participants were randomly assigned to eat the equivalent of an average clove of garlic in either raw form or garlic pills, or dummy pills, six days weekly for six months.
Raw garlic was mixed into salsa, fat-free mayonnaise or other condiments spread on portobello mushroom sandwiches, chicken quesadillas and other specialty sandwiches. Participants in the garlic pill and dummy pill groups also got sandwiches, but without garlic.
Bad breath and body odor were reported by more than half the raw garlic eaters, and a handful of people in the supplement groups reported flatulence, but there were no major side effects. There also was virtually no effect on cholesterol levels in any of the groups.
Blood samples were taken monthly to detect any changes in cholesterol readings but found none that were statistically significant. Diet and exercise levels also were monitored to detect any changes that could affect cholesterol levels.
Robert Borris, a scientist with the Council for Responsible Nutrition, a trade group for nutritional supplement makers, said the study doesn't answer whether garlic might help regulate cholesterol levels in healthy people.
The results also don't refute scientific evidence suggesting that garlic can reduce the tendency of blood platelets to build up and form clots that could block arteries, Borris said.
"I certainly would not give up on garlic," he said.