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| Date: 01-13-2017 | HC# 121631-560 |
Ho XL, Tsen SY, Ng MY, Lee WN, Low A, Loke WM. Aged garlic supplement protects against lipid peroxidation in hypercholesterolemic individuals. J Med Food. 2016;19(10):931-937.
Although the health benefits of raw garlic (Allium sativum, Amaryllidaceae) consumption have been well studied, little is known about the effects of aged garlic intake. The organosulfuric and phenolic compositions of garlic are significantly altered during the aging process; the resultant differences in phenolic and organosulfur profiles may influence the biological activities, if any, of aged garlic preparations. Studies of the effects of aged garlic extract (AGE) on serum cholesterol concentrations have yielded mixed results. These authors conducted a randomized, placebo-controlled, parallel-arm, double-blind trial to simultaneously examine and compare the blood lipid-lowering and antioxidant effects after acute and extended intakes of AGE and raw garlic extract (RGE). The aged and raw garlic powders were prepared and encapsulated by Defu Foodstuff Pte Ltd. (Singapore, Singapore). The raw and aged garlic cloves were slow-heat dried, powdered, and packed into capsules.
The 13-week study was conducted at Nanyang Polytechnic in Singapore, Singapore. Inclusion criteria were Asian ethnicity, age between 21 and 60 years, high blood cholesterol level (between 197.2 mg/dL and 309.4 mg/dL), and body mass index (BMI) between 20 and 30 kg/m2. Forty-one patients who met the criteria and who were normotensive and normoglycemic were enrolled in the study.
The patients were randomly assigned to consume either 1 AGE capsule containing 1080 mg organic fermented aged garlic or 1 RGE capsule containing 1080 mg raw garlic, at baseline for the acute treatment, and then daily for 13 weeks. Baseline clinical information, including age, gender, medical history, weight, and height, was recorded for each patient. The 20 patients assigned to the RGE group and the 21 patients in the AGE group were similar in age, weight, height, BMI, and blood pressure before and after the study.
At baseline, fasting whole blood and spot urine samples were collected from each patient, after which the acute treatment phase of the study was conducted over a 15-minute period. Three hours later, a second set of blood and spot urine was taken and blood pressures were reassessed. Each patient was then instructed to consume the assigned garlic supplements daily for 13 weeks and to maintain weight and activity levels along with usual garlic consumption. After 13 weeks, another set of fasting whole blood and urine was collected and blood pressures were recorded.
Total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, fasting glucose, and high-sensitivity C-reactive protein (hs-CRP) concentrations were measured. Other measured markers of oxidative stress and inflammation included F2-isoprostanes measured in blood plasma and urine, creatinine and urea concentrations determined in urine, lipid hydroperoxides measured in plasma, and serum myeloperoxidase enzyme activity.
The authors report that blood glucose and serum hs-CRP concentrations did not change significantly throughout the study. The clinically high concentrations of blood cholesterol, LDL, and triglycerides were not affected by either the aged or raw garlic supplementation acutely or after 13 weeks. "Until the exact garlic components contributing to the potential hypolipidemic effects of aged and unaged garlic have been identified, and the possible mechanisms by which these molecules exert their effects have been elucidated, we cannot explain, in full, the lack of hypolipidemic actions in our two garlic preparations," write the authors.
F2-isoprostane and lipid hydroperoxide concentrations were significantly decreased after 13 weeks in the AGE group (P<0.05 for all) but not acutely at 3 hours after the 1-time consumption. Acute and extended treatment with RGE did not influence F2-isoprostane or lipid hydroperoxide concentrations. After 13 weeks, serum myeloperoxidase activity was significantly lower in the AGE group but was not changed in the RGE group. The serum myeloperoxidase activity was not affected by acute AGE intake. The total phenolic content of the 2 extracts was determined, and the amount of S-allylcysteine, which reportedly contributes to garlic's antioxidant activity, was measured in the 2 extracts. Significantly greater amounts of phenolic compounds and S-allylcysteine were found in the AGE compared with the RGE.
Antioxidant effects of garlic preparations, both aged and unaged, have been reported in numerous in vitro and human studies. Most of those studies, however, have not explained the possible mechanisms involved in the antioxidant properties garlic extracts exert. "The greater antioxidant activity of the aged garlic may be attributed to its comparatively higher phenolic contents," state the authors. The authors conclude that the results of their study "demonstrated that 13-week treatment with aged garlic, but not its raw garlic precursor, significantly decreased oxidative stress and alleviated lipid peroxidation in hypercholesterolemic subjects." More studies are needed to identify the specific phenolic compounds in aged garlic responsible for its antioxidative activity. Defu Foodstuff Pte Ltd. rendered advice and support for this study. One of the authors (A. Low) is an employee of the company.
—Shari Henson
