Decreasing, null and increasing effects of eight popular types of ginseng on acute postprandial glycemic indices in healthy humans: the role of ginsenosides

Background: It is unclear whether other ginseng sources can replicate the glycemic-lowering efficacy observed previously with American ginseng and whether ginsenosides are mediators. We assessed the effect of eight popular ginseng types on postprandial plasma glucose (PG) and insulin (PI) indices, linking effects to ginsenoside profiles. Methods: Using a double-blind, randomized, multiple-crossover design, 12 healthy participants (gender: 6M:6F, age: 34 ± 3 y, BMI: 25.8 ± 1.2 kg/m2) received 10 3g treatments: American, American-wild, Asian, Asian-red, Vietnamese-wild, Siberian, Japanese-rhizome, and Sanchi ginsengs and two placebos. Each treatment was given 40-minutes before a 75g-oral-glucose-tolerance-test (75g-OGTT) with blood drawn at -40, 0, 15, 30, 45, 60, 90, 120-minutes. HPLC-UV analysis quantified seven principal ginsenosides. Results: Two-factor analysis showed the main effects of ginseng-type and time were significant for PG and PI, with an interaction for PG (p < 0.05). Subsequent one-factor analysis showed an effect of ginseng-type on 90-min-PG and 90-min-PI (p < 0.05). This was reflected in effects on peak-PG, area under the curve (AUC)-PG and AUC-PI (p < 0.05). But the effect on 90-min-PI and AUC-PI were significant (p < 0.05) only in overweight participants (BMI > 25 kg/m2, n = 6). Planned comparisons with placebo showed a tendency for American ginseng and Vietnamese ginseng to lower 90-min-PG (p < 0.06), while Asian ginseng raised peak-PG and AUC-PG, American-wild ginseng raised 120-min-PG, and Siberian ginseng raised 90-min-PG, 120-min-PG, and AUC-PG (p < 0.05). Stepwise-multiple-regression assessed the protopanaxadiol:protopanaxatriol (PPD:PPT)-ginsenoside ratio as the sole predictor (p < 0.05) for 90-min-PG (β = -0.43, r2 = 0.072), AUC-PG (β = -0.25, r2 = 0.06), 90-min-PI (β = -0.26, r2 = 0.065), AUC-PI (β = -0.20, r2 = 0.04). Conclusions: Ginseng has variable glycemic effects, in which the PPD:PPT-ginsenoside ratio might be involved. But the low variance explained suggests the involvement of other unmeasured ginsenoside or non-ginsenoside components.