Confused on Garlic Products: JAMA Study on Garlic Oil Not Applicable to Most Garlic Products in U.S.
Confused on Garlic Products:
JAMA Study on Garlic Oil Not Applicable to Most Garlic Products in U.S.
Herb experts question the conclusion of a study published in JAMA yesterday that garlic is not helpful in lowering cholesterol. The study was based on a garlic oil product that may not contain one of garlic's key therapeutically active compounds, allicin. "It's obvious that the active principle deteriorates in the steam-distilled oil preparation so they shouldn't expect any significant biological activity, unless the product is prepared fresh for each usage," said Varro Tyler, former Dean of Pharmacy at Purdue University and a trustee of the American Botanical Council.
Tyler is senior author of an herbal medicine textbook widely used in pharmacy schools, and co-author of Rational Phytotherapy: A Physician's Guide to Herbal Medicine. The book states that according to clinical studies published in Germany, where the JAMA study originates, preparations made from garlic oil are not as effective as garlic powder.
"Steam-distilled garlic oil is not chemically identical to fresh garlic or dried garlic powder," asserts Mark Blumenthal, founder and executive director of the American Botanical Council. The placebo-controlled study published in JAMA involved administration of 5 mg oil capsules twice daily, on and off for six months. Based on the study's results, the JAMA article reaches the following conclusion: "The commercial garlic preparation investigated had no influence on serum lipoproteins, cholesterol absorption, or cholesterol synthesis. Garlic therapy for treatment of hypercholesteremia cannot be recommended on the basis of this study."
"The authors draw an illogical conclusion," comments Blumenthal. "Garlic oil does not represent all garlic preparations, or even the benefits of whole garlic as a food." The leading garlic product in Europe, Kwai, manufactured by Lichtwer Pharma of Berlin, is made of a standardized garlic powder. This powder contains the chemicals alliin and alliinase which produce another compound, allicin, the focus of much of the European research on garlic. The majority of clinical studies on Kwai do suggest a cholesterol-lowering activity, especially of LDL ("bad") cholesterol.
The JAMA study's primary author, Dr. Heiner K. Berthold, claimed that the garlic oil was chemically similar to powdered garlic preparations, and included allicin. Dr. Joerg Gruenwald, head of PhytoPharm Consulting in German and former director of research at Lichtwer Pharma in Berlin, and an acknowledged expert on garlic research, said, "Products based on the steam-distilled oil of garlic do not contain the chemical alliin which is essential in forming allicin." He stressed that various garlic products contain different chemical composition and biological activity.
According to Jeanette Schubert of Lichtwer Pharma USA in Pittsburgh, "There are at least 12 clinical studies indicating beneficial cholesterol-lowering activity of Kwai, the leading European garlic product. There are a total of 46 clinical studies on all of Kwai's therapeutic effects."
A manufacturer of a leading garlic product from Japan was clear about the implications of this study. Bill Stirling, Director of Marketing at Wakunaga, makers of Kyolic garlic, said "These negative results do not apply in any way to Kyolic Aged Garlic Extract. All research on Kyolic is published in peer-reviewed journals independent of company influence and show that Kyolic consistently helps drop cholesterol levels. We would much rather talk about the positive science on Kyolic than these negative results on lesser products."
Blumenthal pointed out that this issue raises the need for responsible assessment of research on herbs. "Not all herbal products are alike. The method of preparation of various commercial herbal products has a major influence on their activity in the human body."
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