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Aged Garlic Supplement Protects Against Lipid Peroxidation in Hypercholesterolemic Individuals

Ho, Xing Lin, Tsen, Shin Yih, Ng, Mei Yen, Lee, Wei Ni, Low, Aileen, Loke, Wai Mun
Journal of medicinal food 2016 v.19 no.10 pp. 931-937
acute effects, antioxidant activity, blood lipids, blood serum, garlic, humans, hydroperoxides, hypercholesterolemia, in vitro studies, lipid content, lipid peroxidation, lipids, myeloperoxidase, neutrophils, oxidative stress, urine
The health benefits of raw garlic intake has been extensively studied, but little is known about the biological effects of aged garlic consumption. 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 (1080 mg daily). Aged and raw garlic did not affect blood lipid concentrations in these hypercholesterolemic participants after acute and 13-week supplementation. The plasma and urinary F₂-isoprostanes concentrations were significantly decreased after 13 weeks of aged garlic treatment. Aged garlic supplementation over 13 weeks also significantly decreased serum lipid hydroperoxide concentration and myeloperoxidase activity. Raw garlic treatments 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 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 to contain significantly higher total phenolic and S-allylcysteine contents than the raw garlic precursor. Our data showed that supplementation with aged garlic, not its raw garlic precursor, 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.