American ginseng (Panax quinquefolius L) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes mellitus

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.

DESIGN

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.

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 3 g of AG was taken 40 minutes before a 25 g glucose challenge.

METHODS

Ten nondiabetic individuals (6M:4F; mean +/- STD: age = 41 +/- 13 years, BMI = 24.8 +/- 3.5 kg/m2, FBG = 4.5 +/- 0.1 mmol L(-1)) on 12 separate occasions, randomly received 0 (placebo), 3, 6 or 9 g of ground AG root at 40, 80, or 120 minutes before a 25 g 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 9 g of AG reduced (p<0.05) postprandial incremental glucose at 30, 45 and 60 minutes; also, 3 and 9 g of AG did so at 90 minutes. At 60 minutes, 9 g of AG reduced incremental postprandial glucose relative to 3 g of AG (p<0.05). All AG doses reduced (p<0.05) area under the incremental glucose curve (3 g, 26.6%; 6 g, 29.3%; 9 g, 38.5%). AG taken at different times did not have an additional influence on postprandial glycemia.

CONCLUSIONS

In nondiabetic individuals, 3, 6 or 9 g of AG taken 40, 80 or 120 minutes before a glucose challenge similarly improved glucose tolerance.

DNA identification of commercial ginseng samples

An investigation was performed with the objective of developing a DNA-based protocol for the identification of commercial samples of the herbal compound ginseng. There are currently two major herbal products referred to as ginseng. They are Korean or Chinese ginseng (Panax ginseng) and American ginseng (Panax quinquefolius). The market for ginseng in the United States is estimated to be approximately $300 million annually. Current tests for ginseng species identification rely on expert botanical identification of fresh plant/root specimens or on biochemical characterization of active and marker compounds (e.g., ginsenosides). For the determination of the feasibility of ginseng identification by DNA analysis, a strategy based on the direct DNA sequence analysis of the nuclear ribosomal internal transcribed spacer region was developed. Other genetic tests included sequence analysis of the chloroplast ribulose 1,5-bisphosphate carboxylase large subunit gene and DNA fingerprinting by the rapid amplification of polymorphic DNA technique. To confirm the results, each ginseng sample was identified using high-performance liquid chromatography. All methods were successful in distinguishing American from Korean ginseng. In addition, the protocol was improved for the isolation of genomic and plastid DNA from commercial ginseng preparations by incorporating an impact homogenization step into the standard column chromatography purification procedure.