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Comparing Effects of 3 Sources of Garlic on Cholesterol Levels

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ClinicalTrials.gov Identifier: NCT00056511
Recruitment Status : Completed
First Posted : March 18, 2003
Last Update Posted : August 18, 2006
Office of Dietary Supplements (ODS)
Information provided by:
National Center for Complementary and Integrative Health (NCCIH)

March 14, 2003
March 18, 2003
August 18, 2006
May 2002
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LDL-cholesterol; measured at baseline, once a month, and post-intervention
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Complete list of historical versions of study NCT00056511 on ClinicalTrials.gov Archive Site
  • HDL-cholesterol; measured at baseline, once a month, and post-intervention
  • Triacylglycerols; measured at baseline, once a month, and post-intervention
  • Blood pressure; measured at baseline, once a month, and post-intervention
  • Platelet aggregation; measured at baseline, once a month, and post-intervention
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Comparing Effects of 3 Sources of Garlic on Cholesterol Levels
Comparing Effects of 3 Sources of Garlic on Serum Lipids
The purpose of this study is to determine whether fresh garlic can positively affect cholesterol in adults with moderately high cholesterol levels. This study will also determine whether the same effects can be found for two main types of garlic supplements: a dried powdered garlic (designed to yield the same effect as fresh garlic) and an aged garlic extract preparation.

Garlic supplements are the most consumed herbal products in the United States. The most common health claim made for garlic supplements is cholesterol lowering activity. This claim has not been supported by recent clinical trials and meta-analyses. However, data suggest that it is not necessarily the garlic that has been ineffective, but rather the particular garlic preparations being used. To date, the predominant type of garlic preparation used in these clinical trials has been dried garlic powders. A few clinical trials have reported beneficial lipid effects using an aged garlic extract, and only a small number of inconclusive uncontrolled trials have used fresh garlic. A rigorous trial directly comparing different types of garlic preparations for their effects on serum lipids is needed.

Adults with moderately elevated low density lipoprotein cholesterol (LDL-C) will be randomized to one of four groups for 6 months: fresh garlic, dried powdered garlic tablets, aged garlic extract tablets, or placebo control. The fresh garlic will be provided to patients with "study sandwiches"; all other groups will receive the same study sandwiches without the garlic. All patients will take daily study tablets, but the tablet assignment will be double-blind. Patients will pick up study sandwiches twice a week and study tablets once every 2 weeks for 28 weeks. Blood samples will be taken once a month, with additional blood draws at the start and end of the study.

Phase 2
Phase 3
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double
Primary Purpose: Treatment
Drug: Fresh garlic or garlic supplements
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Gardner CD, Lawson LD, Block E, Chatterjee LM, Kiazand A, Balise RR, Kraemer HC. Effect of raw garlic vs commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial. Arch Intern Med. 2007 Feb 26;167(4):346-53.

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
April 2005
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Inclusion Criteria:

  • LDL-C 130-190 mg/dL (fasting single sample)
  • BMI (body mass index) 19-30 kg/m2 (42-66 lb/m2)
  • Weight stable for last 2 months
  • Not actively on a weight loss plan
  • Ethnicity representative of local population
  • No plans to move from the area over the next 9 months

Exclusion Criteria:

  • Pregnant, lactating, within 6 months postpartum, or planning to become pregnant in the next year
  • Diabetes (type I or II) or history of gestational diabetes
  • Heart disease
  • Active neoplasms
  • Renal or liver disease
  • Hyperthyroidism or hypothyroidism
  • Lipid lowering medications (known to affect lipid metabolism, platelet function, or antioxidant status)
  • Blood pressure medications
  • Excessive alcohol intake (self reported, more than 3 drinks/day)
  • Currently under psychiatric care or severely clinically depressed
Sexes Eligible for Study: All
30 Years to 65 Years   (Adult)
Contact information is only displayed when the study is recruiting subjects
United States
R01AT001108-01( U.S. NIH Grant/Contract )
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National Center for Complementary and Integrative Health (NCCIH)
Office of Dietary Supplements (ODS)
Principal Investigator: Christopher D. Gardner, Ph.D. Stanford Center for Research in Disease Prevention
National Center for Complementary and Integrative Health (NCCIH)
August 2006

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP