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.

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.

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