By Sandra Nomoto
Clinical Study Evaluated Cognitive Enhancement and Anti-Stress Effects
A study in Japan that began last year and was published earlier this year expanded on research done on animals using the leaves of Siberian ginseng or eleuthero (Eleutherococcus senticosus) and water extract of rhizomes (plant stem or rootstalk) of gu-sui-bu (Drynaria fortunei, also known as Drynaria roosii or Aglaomorpha fortunei). The first placebo-controlled, randomized, double-blind 12-week study evaluated cognitive enhancement and anti-stress effects through intake of a combined extract in healthy volunteers. The extract appeared to safely enhance a part of memory function in healthy adults.
Siberian ginseng is a species of woody shrub in the Araliaceae family. Its leaves can be used in food and beverages, and the rhizomes and roots are recorded as a treatment for neurasthenia, hypertension, chronic coughing, and ischemic heart disease in Chinese and Japanese pharmacopoeias.
The dried rhizomes of gu-sui-bu have been used in traditional medicine in mainland China, Korea, and Japan to tonify the kidneys, strengthen bones, and promote the healing of fractures.
The Study
All participants completed a basic sociodemographic and medical history questionnaire prior to the study, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was the primary neurocognitive outcome measure. Four stress responses were also evaluated: autonomic symptoms, tiredness/physical responses, anxiety/uncertainty, and depression/feeling of insufficiency. The Mini Mental State Examination (MMSE) was administered as a secondary outcome measure.
Each volunteer was given three capsules to take once daily. The combination of doses in the extracts (not placebos) was determined by previous animal studies. The RBANS analyses compared the total score, five domain scores, and 12 subdomain scores between the extract and placebo groups.
Study Results
Intaking the Siberian ginseng and gu-sui-bu extract for 12 weeks significantly enhanced the “language” domain and “figure recall” and “semantic fluency” subdomains in the RBANS test in those who took extracts.
MMSE scores did not change between groups, but the anxiety/uncertainty and depression/feeling of insufficiency stress responses were significantly reduced for those who took extracts. Interestingly, total cholesterol and HDL-cholesterol levels decreased with placebo intake.
Asians between 43 and 79 were sampled, so the results cannot be generalized to other populations. Although participants were advised not to modify their eating habits and activity patterns, daily dietary intake and physical activity levels were not examined, which may have also been factors in the study results.
In conclusion, using a potential treatment combining Siberian ginseng leaves and water extract of gu-sui-bu rhizome may enhance cognitive function in healthy human adults, without any adverse effects.
This article is based on information in the Nutrients journal by Chihiro Tohda, Mie Matsui, Yuna Inada, Ximeng Yang, Tomoharu Kuboyama, Yoshiyuki Kimbara, and Hidetoshi Watari.