A new US research study shows that garlic does not lower cholesterol, contrary to popular belief.
The study is published in the Archives of Internal Medicine.
The scientists, led by Dr Christopher Gardner at the Stanford Prevention Research Center, California, tested raw garlic and two well known garlic supplements in adults with moderately elevated levels of LDL or “bad” cholesterol.
They found that despite the widespread claims, none of the three forms of garlic lowered cholesterol.
Dr Gardner said that the only way to lower bad cholesterol is to maintain a good diet. Pills and herbs can’t undo the damage of unhealthy eating.
Previous studies on the efficacy of garlic have given conflicting results. Some claim it lowers cholesterol, others say it has no effect.
The Stanford researchers used raw garlic and two kinds of garlic supplement because the phytochemical composition of garlic varies widely.
Phytochemicals are compounds in edible plants that are not essential nutrients for the body to function but have a beneficial effect, particularly for relieving symptoms of illness and fighting disease.
Garlic contains the chemical compound alliin which on crushing becomes allicin, a non-essential amino acid, with antibiotic and antifungal properties that has been shown to dissolve cholesterol in test tubes.
Allicin is unstable and degrades on cooking, which is one reason garlic is often available as supplements.
Gardner and colleagues recruited 192 adults with slightly elevated LDL cholesterol levels, classed as “moderate hypercholesterolemic”. The concentrations of LDL in their blood ranged from 130 to 190 mg/dL. Patients with higher LDL levels would be on cholesterol-busting drugs like statins.
The participants were randomly assigned to one of four groups. One group was tested with raw garlic, another with powdered garlic supplement, a third with aged garlic extract supplement, and the fourth group took a placebo.
The garlic consuming participants took a dose equivalent to an average 4 gram clove of garlic for 6 days a week for 6 months. In the raw garlic group the garlic was in a sandwich.
Their blood was tested every month for LDL and HDL cholesterol and triglycerides, as was the chemical stability of the study materials, which was maintained at a high level throughout the trial.
The study showed no statistically significant effect of any of the 3 forms of garlic at the stated doses on any of the cholesterol or triglyceride readings.
LDL stands for low density lipoprotein, a cholesterol and triglyceride transporter that has been linked to cardiovascular disease. It is not the cholesterol itself that is bad, but the way it is moved around the body that causes problems. LDL delivers cholesterol to arteries which can get clogged up by too much LDL.
HDL stands for high density lipoprotein. HDL also carries cholesterol but mainly from various parts of the body to the liver. It is labelled “good” cholesterol because it transports it away from arteries to the liver.
Cholesterol is essential for healthy cells, it keeps cell membranes pliable which helps nutrients, hormones and waste products to pass in and out of cells.
“Effect of Raw Garlic vs Commercial Garlic Supplements on Plasma Lipid Concentrations in Adults With Moderate Hypercholesterolemia: A Randomized Clinical Trial.”
Christopher D. Gardner, Larry D. Lawson,Eric Block, Lorraine M. Chatterjee, nAlexandre Kiazand, Raymond R. Balise, and Helena C. Kraemer.
Arch Intern Med. 2007;167:346-353.
Vol. 167 No. 4, February 26, 2007.
Click here for information on cholesterol and health (BBC). (resource no longer available at www.bbc.co.uk)
Written by: Catharine Paddock
Writer: Medical News Today