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Allicin Bioavailability From Garlic Supplements and Garlic Foods

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified November 2009 by Silliker, Inc..
Recruitment status was:  Active, not recruiting
National Center for Complementary and Integrative Health (NCCIH)
Information provided by:
Silliker, Inc. Identifier:
First received: April 1, 2009
Last updated: November 18, 2009
Last verified: November 2009

This study will measure the bioavailability of allicin, the main active compound of garlic, from garlic supplements and garlic foods (raw, cooked, processed) so that

  • supplement manufacturers and clinical investigators know how supplements need to be made and consumed to obtain high bioavailability
  • consumers can know how garlic can be prepared to obtain any established health benefits of garlic.

Condition Intervention Phase
Healthy Other: crushed garlic clove Dietary Supplement: garlic powder tablet Early Phase 1

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Allicin Bioavailability of Garlic Products

Resource links provided by NLM:

Further study details as provided by Silliker, Inc.:

Primary Outcome Measures:
  • Breath allyl methyl sulfide [ Time Frame: 1-32 hours ]

Estimated Enrollment: 12
Study Start Date: April 2009
Estimated Study Completion Date: April 2011
Estimated Primary Completion Date: April 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: 1
Positive control with 100% allicin bioavailability
Other: crushed garlic clove
1 gram crushed garlic in gelatin capsules, one dose once every 2-16 weeks
Other Name: Allium sativum
Experimental: 2
garlic powder tablet
Dietary Supplement: garlic powder tablet
tablets, dose to contain 1 gram of garlic powder, consume one dose once every two weeks for up to 52 weeks
Other Name: Kwai, Garlique

Detailed Description:

The bioavailability of allicin, the main active compound of garlic, from garlic supplements and garlic foods is highly questionable and unpredictable from in vitro tests, due to dependence upon alliinase activity under conditions that challenge alliinase activity (heat, gastric acid, intestinal proteases). It is likely that garlic supplement manufacturing procedures and coatings, meal conditions when supplements are consumed (high or low protein), and garlic food preparation conditions (temperature, surface area) will greatly affect allicin bioavailability. Such variability may account for some of the many conflicts seen in clinical trials on cardiovascular disease risk factors.

To resolve these issues, this study will determine the actual bioavailability of allicin from several types of garlic supplements and garlic foods under various conditions. Bioavailability will be determined by measuring the area under the 32-hour curve for breath concentrations of allyl methyl sulfide, the main metabolite allicin.


Ages Eligible for Study:   18 Years to 72 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • in good health (self-judged)
  • BMI (body mass index): 19-32 kg/m2
  • not planning to move out of the area in the next year
  • willing to abstain from consuming garlic and onion and foods that contain them for two days prior to and during each test (diet restrictions)
  • able to deliver bags of breath to the research facility five times in two days
  • willing to eat whole wheat tuna sandwiches

Exclusion Criteria:

  • known serious health problems: diabetes, heart disease, active neoplasms, renal or liver disease, hyper- or hypothyroidism, breathing disorders, gastroesophageal reflux disease (GERD), gastrointestinal disease (absorption interference)
  • known allergy to garlic or wheat
  • tobacco user
  • excessive alcohol intake (³2 drinks/day, self-reported)
  • unable to speak English well
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00874666

United States, Utah
Silliker, Inc.
Orem, Utah, United States, 84058
Sponsors and Collaborators
Silliker, Inc.
National Center for Complementary and Integrative Health (NCCIH)
Principal Investigator: Larry D Lawson, Ph. D. Silliker, Inc.
  More Information

Responsible Party: Larry D. Lawson, principal investigator, Silliker, Inc. Identifier: NCT00874666     History of Changes
Other Study ID Numbers: R21AT004236 ( U.S. NIH Grant/Contract )
1R21AT004236-01 ( U.S. NIH Grant/Contract )
Study First Received: April 1, 2009
Last Updated: November 18, 2009

Keywords provided by Silliker, Inc.:
allyl methyl sulfide
healthy persons

Additional relevant MeSH terms:
Anti-Infective Agents
Hypolipidemic Agents
Molecular Mechanisms of Pharmacological Action
Lipid Regulating Agents
Protective Agents
Physiological Effects of Drugs
Hypoglycemic Agents
Free Radical Scavengers processed this record on September 21, 2017