This trial is active, not recruiting.

Condition healthy
Treatments crushed garlic clove, garlic powder tablet
Phase phase 0
Sponsor Silliker, Inc.
Collaborator National Center for Complementary and Alternative Medicine (NCCAM)
Start date April 2009
End date April 2011
Trial size 12 participants
Trial identifier NCT00874666, 1R21 AT004236-01, R21 AT004236, R21AT004236


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.

United States No locations recruiting
Other countries No locations recruiting

Study Design

Allocation non-randomized
Endpoint classification bio-availability study
Intervention model crossover assignment
Masking open label
Primary purpose basic science
(Active Comparator)
Positive control with 100% allicin bioavailability
crushed garlic clove Allium sativum
1 gram crushed garlic in gelatin capsules, one dose once every 2-16 weeks
garlic powder tablet
garlic powder tablet Kwai, Garlique
tablets, dose to contain 1 gram of garlic powder, consume one dose once every two weeks for up to 52 weeks

Primary Outcomes

Breath allyl methyl sulfide
time frame: 1-32 hours

Eligibility Criteria

Male or female participants from 18 years up to 72 years old.

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

Additional Information

Official title Allicin Bioavailability of Garlic Products
Principal investigator Larry D Lawson, Ph. D.
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.
Trial information was received from ClinicalTrials.gov and was last updated in November 2009.
Information provided to ClinicalTrials.gov by Silliker, Inc..