Archive for the ‘Science’ Category

American Ginseng Improves Working Memory in Middle-Aged Adults

Ginseng is widely used in herbal medicine as an ‘adaptogen,’ which is a plant that ameliorates the effects of stress. In particular, ginseng has been recognized as having substantial effects on the central nervous system, but there are few well-designed clinical trials evaluating the effects of American Ginseng (Panax Quinquefolius L.) on human neurological performance.

In a recent study, Ossoukhova et al [1] studied the effects of a single dose of a standardized extract of P. Quinquefolius on the performance of middle-aged (40-60 years old) healthy individuals on a battery of standardized cognitive tests. This same research group had previously studied the effects of single-dose P. Quinquefolius cognitive performance in younger adults [2]. Their hypothesis was that similar cognitive improvement would be observed in an older population, given the normal decline in CNS performance due to aging.

The study was a placebo-controlled, double-blinded, single center, crossover design. A total of 52 subjects were enrolled, and were assessed on 2 days a week apart after informed consent. Subjects were given either placebo or a 200 mg dose of a standardized ginseng extract. All subjects were given the Cognitive Drug Research Battery and the Computerized Mental Performance Assessment System to evaluate cognitive function at 1, 3 and 6 hours after treatment.

The 200 mg dose of ginseng was found to acutely improve overall working memory and spatial working memory at 3 hours after the dose. This study has several limitations; first is the ‘crossover’ design in which all subjects take the treatment (ginseng) and the placebo at some point in the trial. Effects due to the order of treatment (placebo or ginseng) may be present. Second, subjects may exhibit a ‘learning effect,’ in that they become more familiar with the cognitive test battery due to practice.

In summary, this study by Ossoukhova et al suggests that P. Quinquefolius may acutely improve some measures of cognitive performance in middle-aged adults.





1. Ossoukhova, A., et al., Improved working memory performance following administration of a single dose of American ginseng (Panax quinquefolius L.) to healthy middle-age adults. Hum Psychopharmacol, 2015. 30(2): p. 108-22.

2. Scholey, A., et al., Effects of American ginseng (Panax quinquefolius) on neurocognitive function: an acute, randomised, double-blind, placebo-controlled, crossover study. Psychopharmacology (Berl), 2010. 212(3): p. 345-56.



Ginger: An Overview and Summary

Ginger is the rhizome or underground stem of the plant Zingiber officinale, and has been in use as a medicinal plant for millennia in Asia and the Middle East. The plant is typically 1 meter or so high, and the flowers grow directly from the rhizomes which are the fleshy stems of the plant. The leaves are narrow and are shiny green in color. The flowers are yellow in color with red to purplish tint on the edges. The rhizome, which is actually part of the stem of the plant, grows underground and is the primary source for the active components of the plant. The rhizomes appear fleshy, thick and rootlike, and cut portions of the rhizome are yellow in appearance.

Ginger has been used medicinally to treat nausea in pregnancy [1-2], motion sickness [3], arthritis [4], and may lower cholesterol [5]. In a recent meta-analysis, Borrelli et al [2] reviewed the results of 6 double-blinded placebo controlled studies of the efficacy of ginger in relieving the pregnancy-induced nausea. Overall, 4 of the trials found that ginger was more effective than placebo; two of the trials found that ginger was as effective as vitamin B6 in treating this condition. In a double-blinded, placebo controlled trial of 1 gm of daily ginger versus placebo, Grontved et al [3] found that naval cadets on the high seas reported significantly less symptoms of nausea and vomiting in the ginger-treated group as compared with placebo. Altman et al [4] found a significant reduction in pain with standing and with walking short distances in a group of osteoarthritis patients who received ginger extract versus placebo. Finally, Fuhrman et al [5] found that daily administration of 250 µg of ginger extract significantly reduced triglyceride and LDL cholesterol levels in mice.

The active components of ginger are numerous and diverse. In addition, there are substantial chemical differences between the fresh and dried forms of ginger rhizome [6]. The odor of ginger is predominantly derived from its volatile oil which comprises 1-3% of the rhizome. The pungency of the fresh herb is due to compounds known as gingerols; the most abundant of which is [6]-gingerol (1). Dried ginger pungency is derived from the shogaols which are formed from the gingerols during the drying and dehydration process. There is evidence that the [6]-gingerol species is responsible for the triglyceride lowering effects of ginger [7]. In addition, there is some evidence that the anti-nausea properties of ginger are due to anti-serotonergic effects of [6]-gingerol, [6]-shogaol and galanolactone [8-9].




1. White, B., Ginger: an overview. Am Fam Physician, 2007. 75(11): p. 1689-91.

2. Borrelli, F., R. Capasso, and A.A. Izzo, Effectiveness and safety of ginger in the treatment of pregnancy-induced nausea and vomiting – Reply. Obstetrics and Gynecology, 2005. 106(3): p. 640-641.

3. Grontved, A., et al., Ginger root against seasickness. A controlled trial on the open sea. Acta Otolaryngol, 1988. 105(1-2): p. 45-9.

4. Altman, R.D. and K.C. Marcussen, Effects of a ginger extract on knee pain in patients with osteoarthritis. Arthritis Rheum, 2001. 44(11): p. 2531-8.

5. Fuhrman, B., et al., Ginger extract consumption reduces plasma cholesterol, inhibits LDL oxidation and attenuates development of atherosclerosis in atherosclerotic, apolipoprotein E-deficient mice. J Nutr, 2000. 130(5): p. 1124-31.

6. Ali, B.H., et al., Some phytochemical, pharmacological and toxicological properties of ginger (Zingiber officinale Roscoe): a review of recent research. Food Chem Toxicol, 2008. 46(2): p. 409-20.

7. Kadnur, S.V. and R.K. Goyal, Beneficial effects of Zingiber officinale Roscoe on fructose induced hyperlipidemia and hyperinsulinemia in rats. Indian J Exp Biol, 2005. 43(12): p. 1161-4.

8. Huang, Q.R., et al., Anti-5-hydroxytryptamine3 effect of galanolactone, diterpenoid isolated from ginger. Chem Pharm Bull (Tokyo), 1991. 39(2): p. 397-9.

9. Yamahara, J., et al., Inhibition of cytotoxic drug-induced vomiting in suncus by a ginger constituent. J Ethnopharmacol, 1989. 27(3): p. 353-5.