Effects of black and white garlic supplements on the lipid biochemistry profile in mildly hypercholesterolemic individuals
School of Chemical & Life Sciences
A randomized, placebo-controlled, parallel-arm, double-blinded trial involving 41 hypercholesterolemic individuals was conducted to simultaneously examine and compare the blood lipid lowering and antioxidant effects after acute and extended exposures to aged and raw garlic supplements (1080mg daily). Aged and raw garlic did not affect blood lipids concentrations in these hypercholesterolemic participants after acute and 13-week supplementation. The plasma and urinary F2-isoprostanes concentrations were significantly decreased after 13-week aged garlic treatment. Aged garlic supplementation over 13 weeks significantly also reduced serum lipid hydroperoxides concentrations and myeloperoxidase activity. Raw garlic treatments over 13 weeks did not affect the F2-isoprostanes concentrations in blood plasma and urine, and lipid hydroperoxides in blood sera. Acute effects on the measured parameters were absent for both aged and raw garlic treatments. In separate in vitro experiments, aqueous methanolic extract of aged garlic inhibited F2-isoprostanes formation and myeloperoxidase activity in freshly isolated human neutrophils to a greater extent than the raw garlic extract and S-allylcysteine at equivalent dosing concentrations. The aged garlic preparation was found tocontain significantly higher total phenolic and S-allylcysteine contents than the raw garlic precursor. Our data showed that aged garlic, not its raw garlic precursor, supplementation reduced oxidative stress and alleviated lipid peroxidation, possibly via the inhibition of myeloperoxidase. The differential antioxidant actions of the aged and raw garlic may be related to their different total phenolic contents and, to a lesser extent, their S-allylcysteine contents.