Garlic doesn’t lower cholesterol? That really stinks
Garlic may make your food taste good and your breath reek, but contrary to the highly touted claims of supplement makers, it does nothing to reduce cholesterol levels, Stanford University researchers reported Monday.
Whether it was raw garlic, aged garlic or garlic extract, the popular supplement had no effect on cholesterol in people with moderately high levels, according to the report in the Archives of Internal Medicine.
“It just doesn’t work,” said Christopher Gardner, a Stanford professor of medicine who led the study. “If garlic was going to work, in one form or another, then it would have worked in our study. The lack of effect was compelling and clear.”
The only significant side effect observed in the study occurred among those who consumed raw garlic. Half of them reported persistent bad breath and body odor.
In an editorial accompanying the paper in the journal, Drs. Mary Charlson and Marcus McFerren of the Weill Cornell Medical College in New York City wrote that the authors “convincingly demonstrate that raw garlic and two popularly used supplements do not reduce cholesterol.”
The study did not rule out the possibility that garlic has some other beneficial effects on the cardiovascular system, Gardner said, but those potential effects need to be studied in similar trials.
Robert Borris, a botanical scientist at the Council for Responsible Nutrition, a trade group for supplement manufacturers, said that the study was welldesigned, but that the researchers erred in treating garlic like a drug rather than a supplement that may have a wide range of benefits.
“In a multicomponent natural substance, you have to look at all the effects taken together as opposed to each one taken by itself,” he said.
Garlic has been used for a variety of medical purposes since antiquity, perhaps because of its distinctive, powerful odor.
Recent studies have shown that allicin, the active ingredient of garlic, can block the synthesis of cholesterol in test tubes and animals. Limited trials in humans have shown mixed results.
Gardner reported five years ago that garlic supplements did not lower cholesterol, but biochemist Larry D. Lawson of the Plant Bioactives Research Institute in Orem, Utah, challenged the results, arguing, “How do you know what you delivered?”
The pair, together with chemist Eric Block of the State University of New York at Albany, figured out how to quantify the amount of allicin they were giving subjects, and received $1.5 million from the National Institutes of Health for the six-month study.
“We did everything right, the way we had dreamed of doing it,” Gardner said. “It is the most satisfying study I have ever run, but the results were hugely disappointing. I thought fresh garlic would work.”
The group enrolled 192 healthy adults with moderately high levels of low-density lipoprotein, the so-called bad cholesterol. They were divided into four groups. One group received raw garlic, one received Garlicin powdered garlic, one received Kyolic aged garlic and one received a placebo.
All those receiving garlic received the equivalent of one clove of garlic for six days each week. That is two to four times the recommended dosages of the supplements.
The raw-garlic arm of the study was not blinded. There is simply no way to hide the taste of garlic or to produce a placebo that mimics its taste and smell, Gardner said.
The raw garlic was administered in “heart-healthy gourmet sandwiches” prepared by his laboratory.
Those receiving the supplements also received the sandwiches to match diets as closely as possible.
The team measured cholesterol levels monthly and saw no changes or trends in any type of cholesterol.
“We even looked separately at the participants with the highest versus the lowest cholesterol levels at the start of the study, and the results were identical,” Gardner said. “Garlic just didn’t work.”
Gardner said a healthy use of garlic would be to put it in some hummus or an Asian stir-fry and eat that instead of red meat.
That’s “a good, heart-healthy plant-based diet” that will definitely lower cholesterol, he said.