American ginseng (Panax quinquefolius L.) attenuates postprandial glycemia in a time-dependent but not dose-dependent manner in healthy individuals.
BACKGROUND
We previously showed that 3 g American ginseng administered 40 min before an oral glucose challenge significantly reduces postprandial glycemia in subjects without diabetes. Whether this effect can be replicated with doses <3 g and administration times closer to the oral glucose challenge is unclear.


OBJECTIVE
Our objective was to study the dosing and timing effects of American ginseng on postprandial glycemia.


METHODS
In a random crossover design, 12 healthy individuals [X +/- SEM age: 42 +/- 7 y; body mass index (BMI; in kg/m2): 24.1 +/- 1.1] received 16 treatments: 0 (placebo), 1, 2, or 3 g American ginseng at 40, 20, 10, or 0 min before a 25-g oral glucose challenge. Capillary blood was collected before administration and at 0, 15, 30, 45, 60, and 90 min after the start of the glucose challenge.


RESULTS
Two-way analysis of variance showed that the main effects of treatment and administration time were significant (P < 0.05). Glycemia was lower over the last 45 min of the test after doses of 1, 2, or 3 g ginseng than after placebo (P < 0.05); there were no significant differences between doses. The reductions in the areas under the curve for these 3 doses were 14.4 +/- 6.5%, 10.6 +/- 4.0%, and 9.1 +/- 6%, respectively. Glycemia in the last hour of the test and area under the curve were significantly lower when ginseng was administered 40 min before the challenge than when it was administered 20, 10, or 0 min before the challenge (P < 0.05).


CONCLUSIONS
American ginseng reduced postprandial glycemia in subjects without diabetes. These reductions were time dependent but not dose dependent: an effect was seen only when the ginseng was administered 40 min before the challenge. Doses within the range of 1-3 g were equally effective.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto. v.vuksan@utornto.ca
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V
Vuksan
J L
JL
Sievenpiper
J
J
Wong
Z
Z
Xu
U
U
Beljan-Zdravkovic
J T
JT
Arnason
V
V
Assinewe
M P
MP
Stavro
A L
AL
Jenkins
L A
LA
Leiter
T
T
Francis
D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D005894:Panax / Q000627:therapeutic use*; D008517:Phytotherapy; D010946:Plants, Medicinal; D019518:Postprandial Period; D013997:Time Factors; D016896:Treatment Outcome
D001786:Blood Glucose