Asian Ginseng and Guarana Improve Cognition

Asian Ginseng and Guarana
Improve Cognition

Commonly paired herbal extracts enhance performance in
mental tasks and alleviate mental fatigue
By Dr. Edward R. Rosick

lthough the mainstream medical establishment may be trying to ignore it, complementary and alternative medicine (CAM) is quietly becoming part of the actual mainstream of American medical culture. Studies have shown that at least 50% of people use some type of holistic medicine—vitamins, herbs, acupuncture, etc.—with most of the cost (40 billion dollars annually, by some estimates) being paid out-of-pocket. Why is this so? Why are so many people willing to shell out their hard-earned money on treatments that many in the establishment call quackery?

One of the main reasons, according to many of my patients, is that establishment medicine can do little, if anything, for many chronic health problems. Take mental fatigue, for instance: can you name one prescription medicine—one that doesn’t have significant side effects, anyway—thats marketed as being able to help with this debilitating problem, which seems to be affecting more and more people? Although I can’t think of one, I can name more then a few natural supplements with which I’ve had great success in my medical practice. One of them is an herb—Asian ginseng—that has been used for thousands of years.

Ginseng—Ancient Herb for Modern Times

Ginseng (Panax ginseng)
Asian ginseng (Panax ginseng) has long been a mainstay of medical practice in China, Korea, and other areas of the Orient, where it is also known as Chinese ginseng, Korean red ginseng, etc.). Chinese characters that represent this remarkable herb have been found inscribed on bones and tortoise shells dating as far back as 3000 B.C. For at least the last 5000 years, Asian ginseng (which we’ll call ginseng for short) has been used to increase stamina, decrease mental and physical fatigue, and give a boost to the libido (see “Firm Up Your Sex Life with Korean Red Ginseng” in the February 2003 issue). In traditional Chinese medicine, ginseng is said to have primarily yang energy.*

*This concept comes from Chinese dualistic philosophy, in which yang and yin represent the opposing forces of the universe. Yang is the male power, characterized as hot, bright, hard, active, etc. Yin is the female power, characterized as cool, dark, soft, passive, etc. The two are regarded as complementary and equally necessary and worthy.

Whether or not you pay much heed to tradition, you should know that modern research on ginseng lends credence to ancient claims regarding its medicinal properties. The major active constituents of ginseng are chemical compounds called ginsenosides, which are members of a larger class of compounds called saponins. Thus far, at least 30 ginsenosides have been identified, and the various pharmacological effects of ginseng have been attributed to different groups of these compounds.

Ginseng Improves Memory

There is an extensive scientific literature of both animal and human studies on ginseng. A review published in 2003 examined numerous such studies, whose cumulative record is impressive.1 One study discussed in the paper was a randomized, double-blind, placebo-controlled crossover trial in which researchers tested ginseng’s effects on the subjects’ ability to perform various mental tasks, using the Cognitive Drug Research (CDR) computerized assessment battery.

The CDR is a standardized test that has been used in over 500 clinical trials to assess both the enhancement and impairment of human cognitive functions (such as speed of attention, speed of memory, accuracy of attention, and working memory) in a clinical setting. Among the CDR tasks are logical reasoning, sentence verification, serial-3s and serial-7s subtraction tasks (in which the subject must mentally subtract the number in question from a large 3-digit number, repetitively and under time pressure), and subjective mood measurements to gauge alertness, calmness, and contentedness.

During the study in question, 20 subjects took a baseline CDR test and then took the supplement—200, 400, or 600 mg of a standardized ginseng extract or placebo. They were then retested several more times over a 6-hour period. Compared with placebo, all three doses of ginseng improved the subjects’ secondary memory factor, which was comprised of percentage accuracy scores from four memory tasks. Interestingly, the 400-mg dose, not the 600-mg dose, produced the best results.

Ginseng and Guarana Work Well Together

Recent studies have confirmed the positive effects of ginseng on a variety of cognitive functions. One study has shown that extracts of ginseng and the South American herb guarana (see the sidebar), both alone and in combination, can enhance cognitive function.2 In this double-blind, placebo-controlled trial, 28 healthy young men and women aged 18–24 were given one of four formulations: 200 mg of a standardized ginseng extract called G115, 75 mg of guarana extract, a combination of the two (in those same amounts), or a placebo. As in the previous study, cognitive function was assessed using the CDR.

Guarana—A Boost from Brazil

Ever heard of guarana? Neither had I until 1996, when I led a team of medical and dental students down the Amazon River, treating indigenous tribespeople. When our group would happen upon a settlement that had electricity—and therefore refrigeration—we would stock up on cold drinks, since drinking warm Amazon water (filtered, of course!) was no treat.

The one cold beverage all the villages seemed to have in ample supply was guarana, which, I learned, was the number one soft drink in Brazil. During my 3-week journey, I consumed gallons of the stuff. The locals teased me that guarana was a potent aphrodisiac—not that I was able to verify this claim, since my wife was thousands of miles away in Los Angeles—but it was tasty and gave a noticeable mental lift. After working 18-hour-long days in 100-degree heat, this pleasant side effect of guarana proved quite welcome.

As I’ve learned since then, guarana (Paullinia cupana) is a woody, evergreen, climbing vine native to the Amazon Basin. Its roasted seeds (which have an odor reminiscent of chocolate) are used for a variety of ailments in Brazilian folk medicine, including fatigue, headaches, and impotence. Although there have been few human studies examining the myriad reported effects of guarana, scientists have identified many of the chemical constituents of this plant, including the alkaloids caffeine, theophylline, and theobromine, as well as various saponins and tannins, the last two being potent antioxidants.1

Guarana (Paullinia cupana)
A number of animal studies have been done using guarana, and most have shown that this herb is safe and nontoxic. In one such study, guarana’s effects on rodents were examined following both acute and chronic (2 years) administration, and these effects were compared to those produced by ginseng, with which guarana is commonly combined.1

The researchers found that guarana has potent antioxidant activity, as indicated by its ability to decrease lipid peroxidation significantly. Regarding any toxic effects, the authors concluded, “In this study, it was possible to observe both in mice and rats that guarana, in the same way as ginseng, did not exert toxic effects. This was demonstrated after acute administration of high doses of these products as well as in chronic treatment at low doses.”

  1. Mattei R, Dias RF, Espinola EB, et al. Guarana (Paullinia cupana): toxic behavioral effects in laboratory animals and antioxidant activity in vitro. J Ethnopharmacol 1998;60:111-6.

Speed-of-memory test scores, showing improvements produced by ginseng, guarana, and their combination. Negative values indicate faster responses. From Ref. 2.
The subjects took the test on five different days, spaced seven days apart in order to ensure adequate washout periods between them. On the first day, there was no treatment—they took the test simply to become familiar with the CDR protocol. On days 2 through 5, a baseline test was immediately followed by the treatment, and the subjects were then retested 1, 2 1/2, 4, and 6 hours later.

Compared with placebo, both ginseng alone and guarana alone, as well as the two combined, improved the subjects’ scores across the CDR test spectrum. Specifically, speed of attention was improved, with guarana producing the best results. Both ginseng and guarana improved the speed of memory factor, the secondary memory factor, sentence-verification time, and performance on the serial-3s and serial-7s subtraction tasks.

Long-Term Use May Be Better

Although there did not appear to be a synergistic effect of the two herbs in this study, the authors stated,

… on the basis of their saponin contents and observations from animal studies, guarana and ginseng might both be classed as ‘resistogens’ or ‘adaptogens’ (i.e., offering protection against the physiological effects of physical or psychological stressors). If this is the case, then the effects of both may increase with chronic dosage, and the possibility exists for a synergistic relationship between their components, which would confer an added advantage over time, potentially both in terms of general health and cognitive performance.

So how did this potent herbal combination improve cognitive function in healthy human subjects? Although the benefits of guarana have generally been ascribed primarily to its caffeine content, the authors concluded that caffeine’s role was probably not significant, because the extract contained only 11–12% caffeine (8–9 mg of caffeine per 75-mg dose, versus, e.g., 100–150 mg in a cup of coffee). Regarding ginseng, they stated, “… while ginseng would appear to exert a wide range of physiological and cognitive effects, the mechanisms underlying them are complex and, to date, poorly understood.”

Ginseng Lowers Blood Glucose Levels

In a subsequent study by the same research group, it was found that ginseng had a hypoglycemic effect (lowering of blood glucose levels), that it enhanced cognitive performance in a mentally demanding task, and that it reduced mental fatigue associated with sustained mental exertion.3 This study, conducted with 30 healthy young adults, used a 10-minute cognitive test battery consisting of serial-3s and serial-7s subtraction tasks, a rapid visual information-processing task, and a subjective test of mental fatigue using a visual analogue scale.

Following a baseline test, the subjects were immediately given 200 or 400 mg of standardized ginseng extract (G115) or placebo. Then, starting 1 hour later, they were given the same 10-minute test six times in succession, for a total of 60 minutes of testing. Their blood glucose levels were measured just before the ginseng was administered, 1 hour later (just before the 1-hour test period began), halfway through the test period, and again after the test was completed.

With regard to cognitive performance, the only significant effect of ginseng was seen in the most difficult test, the serial-7s subtraction task. This occurred with the 200-mg dose (but not the 400-mg dose), which was also associated with slight but significant improvements in the subjective evaluation of mental fatigue.

Both the 200- and 400-mg doses, however, produced significant decreases in blood glucose levels. These results suggest that the cognitive benefits may derive from increased glucose metabolism through enhanced glucose transport into the cells (which lowers the blood levels), but the authors admit that this idea is speculative and could be wrong.

Ginseng and Guarana Can Help Lift the Fog of Mental Fatigue

Modern medicine has made great strides in many areas of healing, such as antibiotics for infection control, sophisticated surgical techniques for repairing all kinds of damage, and now even gene therapy for attacking disease at the most fundamental molecular level (see the article of page 4 of this issue).

In our rush to embrace the latest, greatest (and usually very expensive) prescription medications, however, we should not overlook traditional herbal medicines whose worth has been proved over centuries or even millennia of use. Herbs such as ginseng and guarana, which have long been used by indigenous peoples, can offer real hope for many ailments, such as mental fatigue, that continue to baffle even the most technologically advanced medical system the world has ever known.


  1. Kennedy DO, Scholey AB. Ginseng: potential for the enhancement of cognitive performance and mood. Pharmacol Biochem Behav 2003;75:687-700.
  2. Kennedy DO, Haskell CF, Wesnes KA, Scholey AB. Improved cognitive performance in human volunteers following administration of guarana (Paullinia cupana) extract: comparison and interaction with Panax ginseng. Pharmacol Biochem Behav 2004;79:401-11.
  3. Reay JL, Kennedy DO, Scholey AB. Single doses of Panax ginseng (G115) reduce blood glucose levels and improve cognitive performance during sustained mental activity. J Psychopharmacol 2005;19(4):357-65.

Caution: If you have diabetes, do not take any supplement that may affect your blood sugar levels without first consulting your physician. Diabetes is a serious disease requiring careful professional management.

Dr. Rosick is an attending physician and clinical assistant professor of medicine at Pennsylvania State University, where he specializes in preventive and alternative medicine. He also holds a master’s degree in healthcare administration.

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