 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. 