American ginseng contains phytochemicals (such as ginsenosides) with the potential of health-promoting benefits, including the support of cognitive function and a positive outlook.* In a recent double-blind, randomized, placebo-controlled trial, researchers studied the effects of 200 mg of American ginseng (as Cereboost® standardized to contain 10% to 12% ginsenosides) on mood and cognition. The study included 61 predominantly female participants who were healthy young adults between the ages of 18 and 40 years who were not on any medication, other than possible oral contraceptives. The participants were randomly split into two groups. One group took 200 mg of American ginseng and the other group took a placebo.

At baseline, the participants were screened using mood and cognitive testing. This was followed by repeated testing at 2 hours, 4 hours, and 6 hours to determine the acute effects. The participants then continued to take the supplements daily for 2 weeks, after which they underwent another round of tests to determine the chronic effects of supplementation. Cognition was assessed using a computerized cognitive battery test that evaluated attention, working memory, episodic memory, and mood. The participants also provided two self-reporting questionnaires for the Manual for the Positive and Negative Affect Schedule (PANAS-X) and the Positive and Negative Affect Schedule Now (PANAS-Now) to assess each participant’s current mood and their moods for the prior 2 weeks. The researchers added a question to assess mental fatigue using a 9-point Likert scale.

The single dose of American ginseng supplement led to a significant enhancement of accuracy, faster reaction time, and performance on more cognitively challenging trials compared to a placebo. Chronic supplementation led to a significant enhancement of accuracy, mental fatigue, and mood compared to a placebo. The treatment group also had significantly better performances during postprandial test sessions compared to the placebo group. The researchers concluded that this pattern “highlighted a maintenance of executive function and working memory performance in the immediate postprandial period following Cereboost® treatment, while chronic supplementation also offered some long-term benefits to performance accuracy and to subjective measures of mood and mental fatigue.”

The researchers also tested the hypothesis that the cognitive and mood benefits from American ginseng were in some part related to positive benefits for the gut microbiota. They performed an in vitro experiment on samples from one healthy donor using the Simulator of the Human Microbial Ecosystem (SHIME®). The researchers collected samples of microbial metabolic activity three times per week to analyze levels and fecal samples once per week through quantitative polymerase chain reaction testing to assess the microbial makeup. American ginseng supplementation led to a significant increase of acetate, propionate, butyrate, and total short-chain fatty acid (SCFA) levels compared to the control period. The American ginseng supplementation also significantly reduced Firmicutes levels in all colonic areas and resulted in a significant enrichment of Lactobacillus and Akkermansia muciniphila.

Although more studies are necessary to confirm the efficacy of American ginseng on cognition and mood, along with the potential underlying mechanisms, this study shows promising effects. This study adds to the emerging research on brain and mood health benefits of herbs, such as American ginseng. It also demonstrates additional insight into some of the connections between the gut microbiome and cognitive function and mood. 

By Kendra Whitmire, MS, CNS