In the most rigorous study to date, researchers found no evidence that wild garlic or garlic supplements lower levels of LDL (bad) cholesterol. The findings published in the February 26 Archives of Internal Medicine will disappoint fans of the pungent herb.
Researchers from Stanford University Medical School in California took 192 adults with modestly elevated LDL (bad) cholesterol levels and randomly assigned them to take 1 of 4 treatments 6 days a week for 6 months: Garlicin pills (4 per day), a supplement made from garlic powder; Kyolic tablets (6 per day), a supplement made from aged garlic extract; dummy pills (4 to 6 per day); or wild garlic (4 grams daily) consumed in heart-healthy sandwiches. The pill poppers were also given identical sandwiches without garlic.
At the end of the study, there was no difference in levels of total, LDL (bad), HDL (good) cholesterol, or triglycerides between the 4 groups. Indeed cholesterol levels barely budged in any of the groups during monthly tests.
Although the participants were not told which treatment they were getting, most of the raw garlic group correctly guessed—not surprising, since 57% reported having bad breath or body odor “often” or “almost always”. Only half of those taking garlic or dummy pills correctly guessed which one.
A criticism of previous negative studies on garlic pills is that the products tested did not produce enough allicin, the presumed active ingredient. Allicin is formed when garlic supplements are dissolved or when wild garlic is cut or crushed. The Stanford researchers ran lab tests for 1 year to make sure that the potential active ingredients of all 3 types of garlic would be stable under study conditions. They also used much higher doses of garlic supplement than prior studies (1.5 to 3 times the recommended dose).
Early research in test tubes and animals held promise that garlic may help lower cholesterol levels, but previous studies in people had mixed results. This is the largest and most rigorous test so far for the humble herb.
In October 2000, the Agency of Healthcare Research and Quality in the US Department of Health and Human Services reviewed the research on garlic and concluded that it may have small, short-term effects on cholesterol, but that there was not enough good evidence to support a long-term term cholesterol-lowering benefit.
Unlike drugs, dietary supplements are not reviewed by the Food and Drug Administration (FDA) for safety and effectiveness before being sold. Dietary supplements cannot carry claims to treat or prevent a disease—only approved drugs can do that. However, they can make certain health claims if the product label includes the disclaimer that the FDA has not evaluated the claims.
The authors of the latest study note that garlic might still have other heart or general health benefits, but that these too should be subject to scientific scrutiny.
Source: Archives of Internal Medicine 2007;167:346-353. Reprinted from HealthyWomen.gov
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