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Department of Nutritional Sciences, Faculty of Medicine, University of Toronto (J.L.S., L.A.L., V.V.)
Risk Factor Modification Centre, St. Michael’s Hospital (J.L.S., M.D., L.A.L., V.V.), Toronto
Department of Biology, Faculty of Science, University of Ottawa, Ottawa (J.T.A.), CANADA
Department of Food and Nutrition, Sookmyung Women’s University, Seoul (M.S.)
Korea Ginseng Manufacturing Plant, National Agricultural Cooperative Federation, Chung-buk (K.S.L.)
Korean Ginseng and Tobacco Research Institute, Daejeon (K.Y.N.), KOREA
Address reprint requests to: Vladimir Vuksan, PhD, Clinical Nutrition and Risk Factor Modification Centre, St. Michael’s Hospital, #6 138-61 Queen Street East, Toronto, Ontario, M5C 2T2, CANADA. E-mail: v.vuksan{at}utoronto.ca
Background: Fractionation of a ginseng source to produce differences in the ginsenoside profile might influence its effect on postprandial glycemia. To explore this possibility and identify an efficacious ginseng for a longterm study, we conducted a preparation-finding study of different Korean red ginseng (KRG) root fractions followed by a dose-finding study of the most efficacious fraction.
Methods: A double-blind, randomized, within-subject design was used in both studies. In the preparation-finding study, 7 healthy subjects (sex: 3m:4f, age: 32 ± 4 y, BMI: 24 ± 2 kg/m2) received 6 g placebo and KRG-rootlets, -body, and -H2O extract 40 min before a 50 g-OGTT with finger-prick blood samples at –40-, 0-, 15-, 30-, 45-, 60-, 90-, 120-min. In the dose-finding study, 12 healthy subjects (sex: 9M,3F, age: 29 ± 3 y, BMI: 22.5 ± 1 kg/m2) received 0 g (placebo), 2 g, 4 g, and 6 g of the most efficacious root fraction following the same protocol. Ginsenosides were analyzed using HPLC-UV.
Results: In the preparation-finding study, a wide variation in the ginsenoside profiles was achieved across the 3 KRG fractions. This variation coincided with differential effects. The main effects of KRG-rootlets (p = 0.050) and time (p < 0.001) and their interaction (p < 0.1) were significant. This was reflected in a 29% reduction in area under the curve (AUC) by KRG-rootlets compared with placebo (p = 0.052). Conversely, neither KRG-H2O extract nor KRG-body affected glycemia. Stepwise-multiple regression models identified Rg1 as the sole predictor of mean- and AUC postprandial blood glucose. In the dose-finding study, KRG-rootlets were tested as the most efficacious fraction. A significant effect of KRG-rootlets treatment (mean of 3 doses) but not dose was found. The mean of 3 doses decreased AUC by 17% compared with placebo (p = 0.057).
Conclusions: Together the studies indicate 2 g KRG-rootlets is sufficient to achieve reproducible reductions in postprandial glycemia. But the longterm sustainability of KRG selected using this approach remains to be tested.
Key words: Complementary and Alternative medicine, ginseng, ginsenosides, postprandial glycemia, OGTT
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