American ginseng improves glycemia in individuals with normal glucose tolerance: Effect of dose and time escalation

Objective: We studied the effect of escalating the dose and administration time of American ginseng (AG, Panax quinquefolius L.) in nondiabetic individuals to achieve further improvements in glucose tolerance seen previously when 3g of AG was taken 40 minutes before a 25g glucose challenge. Methods: Ten nondiabetic individuals (6M:4F; mean +/- STD: age = 41 +/- 13 years, BMI = 24.8 +/- 3.5 kg/m(2), FBG = 4.5 +/- 0.1 mmolL(-1)) on 12 separate occasions, randomly received 0 (placebo). 3, 6 or 9g of ground AG root at 40, 80, or 120 minutes before a 25g oral glucose challenge. Capillary blood glucose was measured prior to ingestion of AG or placebo capsules and at 0, 15, 30, 45, 60 and 90 minutes from start of challenge. Results: Compared with the placebo, 3, 6 and 9g of AG reduced (p<0.05) postprandial incremental glucose at 30, 45 and 60 minutes; also, 3 and 9g of AG did so at 90 minutes. At 60 minutes, 9g of AG reduced incremental postprandial glucose relative to 3g of AG (p<0.05). All AG doses reduced (p<0.05) area under the incremental glucose curve (3g, 26.6%; 6g, 29.3%: 9g, 38.5%). AG taken at different times did not have an additional influence on postprandial glycemia. Conclusions: In nondiabetic individuals, 3, 6 or 9g of AG taken 40, 80 or 120 minutes before a glucose challenge similarly improved glucose tolerance.