American ginseng contains ginsenosides, which are thought to fight fatigue and stress by supporting the adrenal glands and the use of oxygen by exercising muscles.⁴ The type and ratio of ginsenosides are somewhat different in American and Asian ginseng. The extent to which this affects their medicinal properties is unclear. A recent preliminary trial with healthy volunteers found no benefit in exercise performance after one week of taking American ginseng.⁵

In a small pilot study, 3 grams of American ginseng was found to lower the rise in blood sugar following the consumption of a drink high in glucose by people with type 2 diabetes.⁶ The study found no difference in blood sugar lowering effect if the herb was taken either 40 minutes before the drink or at the same time. A follow-up to this study found that increasing the amount of American ginseng to either 6 or 9 grams did not increase the effect on blood sugar following the high-glucose drink in people with type 2 diabetes.⁷ This study also found that American ginseng was equally effective in controlling the rise in blood sugar if it was given up to two hours before or together with the drink.