From the lower of total cholesterol by use garlic is believed to be largely due to a reduction in LDL-C, which may be due to an inhibition of hydroxymethylglutaryl-CoA reductase, by allicin. The active principle of garlic, allicin is not formed until the reaction between alliin and alliinase take place in aqueous solutions when fresh garlic is chopped or when garlic powder is dissolved in the stomach. The active alliin-alliinase system is only present in fresh garlic and in carefully dried garlic powder. The amino acid L- alliin and the enzyme alliinase are currently regarded as the marker substances for fresh garlic and powdered garlic preparations. In fresh garlic they are present in separate compartments, so that no enzymic conversion can take place.