Asian Ginseng and Guaraná May Sharpen Mental Function

Ancient Remedies Offer Modern Benefits

Asian Ginseng and Guaraná
May Sharpen Mental Function

Herbs from the Orient and the Amazon improve some
aspects of cognitive function in healthy young adults
By Will Block

emember the movie Rain Man, starring Dustin Hoffman as the dysfunctional but oddly talented Raymond Babbitt? The story had Raymond performing prodigious mental feats, such as doing complex arithmetical calculations in his head in seconds, identifying the day of the week for any given date in the past or future, and memorizing staggering amounts of mostly trivial data.

We’ve all heard about such extraordinary people—intellectually disabled yet gifted with phenomenal memories and seemingly magical abilities in a few highly specialized areas, such as mathematics or music. They’re usually called idiot savants. In Rain Man, though, Raymond was portrayed not as mentally retarded but as an autistic savant, i.e., a man with both autism and the savant syndrome.*

*In real life, the savant syndrome occurs in about 10% of cases of autism, but in only about 0.06% of cases of mental retardation. The latter condition is far more common than autism, however, and the total numbers of idiot savants and autistic savants are about equal.

What many savants have in common is a brain like a computer—not intelligent in the usual sense, but able to store vast amounts of data and to calculate unerringly with lightning speed. Savants are, unfortunately, somewhat like computers in another way: their typical demeanor is flat and emotionless, and they tend to avoid any expressions of affection—a very sad way to live.

Ready . . . Set . . . Subtract!

It’s a safe bet that you’re not a savant of either of the above kinds. Count your blessings. Perhaps, however, you’re a savant in the traditional sense of being a very scholarly and learned person. If so, count higher, for you are blessed with knowledge, and knowledge is power.

Speaking of computing and counting, how good are you at arithmetic? Specifically, how good would you be at starting with a large number and mentally subtracting 7 from it—not once, but repeatedly, for several minutes at a stretch, while under pressure to perform quickly and accurately, without faltering, and knowing that you would be graded on your performance?

Raymond could probably have accomplished this stressful task with ease, but you probably could not, because you’re an intelligent person, with feelings. Not having a computerlike brain, you would soon make a mistake. And when you did, you would feel annoyed and a little embarrassed—not a good recipe for your ongoing attempts at quickness and accuracy as you navigated down the chain of unseen numbers. Your stress level would build up …

Asian Ginseng—An Ancient Heritage

Physiologists use the “serial-7s subtraction test,” and others, to gauge the effects of psychological stress on blood chemistry (the effects can be rapid and dramatic). And psychologists use such tests to observe the effects of altered blood chemistry on cognitive function. How does one alter blood chemistry for this purpose? By ingesting a drug or nutritional supplement that can be expected to make a difference (for the better, one hopes).

One supplement that is believed to improve cognitive function is Asian ginseng (Panax ginseng), a perennial herb whose history of use as a general tonic goes back at least 5000 years. Asian ginseng is also called Chinese ginseng or Korean ginseng (they’re the same species); it should not be confused with American ginseng (a different species) or Siberian ginseng (a different genus). It has traditionally been used for combating physical and mental fatigue, increasing stamina, and boosting libido. Modern science suggests that it may help improve cognitive function by sharpening some of our mental faculties.

A Surprising Result . . .

A group of British researchers has published a study on the effects of Asian ginseng administered both with and without glucose (blood sugar) to healthy young adults who had fasted overnight.1 In a previous study done without supplemental glucose, they had determined that single doses of ginseng lowered glucose levels and improved cognitive performance in mentally demanding tasks, such as the serial-7s subtraction test; ginseng also reduced mental fatigue associated with sustained mental exertion.2 (See “Asian Ginseng and Guarana Improve Cognition” in the September 2005 issue.)

The combination of glucose reduction and cognitive enhancement in that study came as a surprise, because it had long been known that blood glucose levels are positively, not negatively, correlated with cognitive function. In particular, it was known that even moderately reduced glucose levels—low but not low enough to be classified as hypoglycemia—can impair cognitive function. Conversely, ingesting a glucose drink, which causes a temporary spike in blood glucose levels, is known to enhance cognitive function.

The authors speculated that the ginseng had increased the brain’s uptake of glucose. This could account for both the reduced blood levels of glucose and the performance improvements in the cognitive tests—although they noted that there was no correlation between changes in blood glucose and changes in cognitive performance following the treatments.

. . . Leads to Another Study . . .

The ambiguity of those results inspired the new study, using ginseng separately (200 mg of a standardized extract called G115), glucose separately (25 mg), and the two in combination (same amounts), as well as a placebo for reference.1 Thus the four possible treatments were ginseng/placebo, glucose/placebo, ginseng/glucose, and placebo/placebo.

In the new study, 27 healthy young adults who had fasted overnight were given a 10-minute cognitive test battery consisting of serial-3s and serial-7s subtraction tasks, a test to evaluate rapid visual information processing (using sequences of numbers flashing on a computer screen), and a subjective evaluation of the mental fatigue induced by taking those tests. Immediately afterward, they were given either ginseng or placebo in capsule form, followed 30 minutes later by a drink containing either glucose or a saccharin placebo. After waiting another 30 minutes, they again took the 10-minute test battery, six times in a row during the ensuing hour.

Throughout this protocol, the researchers monitored the subjects’ blood glucose levels, which rose whenever glucose was taken, either alone or in combination with ginseng. When ginseng was taken alone, however, blood glucose levels dropped (as in the previous study). This suggests that, although ginseng does have a hypoglycemic effect (in the fasting state, when glucose levels are not elevated), the effect is not strong enough to overcome a modest glucose load, such as would occur after a meal.

. . . And a Modest Conclusion

In the serial-3s subtraction test, the subjects showed a small but significant improvement after taking either ginseng alone or glucose alone; oddly, however, there was no improvement when they took the two in combination. And there were no significant improvements of any kind in the more difficult serial-7s subtraction test. (In the previous study, the results with ginseng were the opposite: improvement in serial-7s but not in serial-3s.) In the test of rapid visual information processing, there were significant improvements with glucose, either alone or with ginseng. And the evaluation of mental fatigue showed small improvements with glucose alone or ginseng alone, but not with the combined treatment.

Although these results were ambiguous and confusing, they were similar to those of the previous study with regard to the positive cognitive effects of ginseng when administered alone in the fasting state. They provided no support, however, for the researchers’ specific hypothesis regarding ginseng’s possible role in glucose metabolism. Indeed, they suggest that ginseng may have opposite effects when administered with glucose or without glucose.

The authors concluded, “These results confirm that Panax ginseng may possess glucoregulatory properties and can enhance cognitive performance.” Not surprisingly, though, they emphasized the need for further research to try to clarify the situation.

Guaraná—From the Amazon Jungle

Another potentially valuable supplement for enhancing cognitive function is guaraná (Paullinia cupana), a climbing shrub native to the Amazon Basin. We know little of its history of use, because the Amazon Indians have no recorded history. We do know, however, that the roasted seeds of guaraná’s small red fruit have long been used in Brazilian folk medicine for a variety of ailments, including fatigue, headaches, and impotence.

Guaraná is also the key ingredient in Brazil’s most popular soft drinks, which are known not just for their refreshingly fruity taste but also for their stimulant effect. This effect is attributed largely to a chemical compound often called guaranine, which is actually caffeine—they’re identical molecules. It constitutes about 2 1/2–5% of guaraná’s dry weight.

Guaraná Is Tested for Cognitive Benefits . . .

Members of the same research team that conducted the experiments on Asian ginseng have also recently investigated the properties of guaraná.3 As with the Asian ginseng study discussed above, this guaraná study was also a follow-up to a previous study by the same group.4 (See the September 2005 article cited earlier.) That study entailed the use of both guaraná and ginseng, as a matter of fact, and the authors had concluded that both of these agents, alone and in combination, enhanced cognitive function in healthy young adults.

In the new study, the researchers again used a standardized test called the Cognitive Drug Research (CDR) computerized assessment battery, which can measure both enhancement and impairment of cognitive function in a clinical setting.3 It consists of many individual tests, in five general categories: speed of attention, speed of memory, accuracy of attention, secondary memory, and working memory. A mood-rating scale was also used, providing subjective evaluations in three categories: alertness, contentedness, and calmness.

Four different doses of guaraná were used in the new study: 37.5, 75, 150, and 300 mg (the earlier study had used only a 75-mg dose). These were extracts of guaraná, containing 11–12% caffeine by weight; thus, assuming 12%, the amounts of caffeine in the four samples were still very low: 4.5, 9, 18, and 36 mg, respectively (only the last of these is considered to be within caffeine’s psychoactive range). By comparison, a typical cup of coffee (brewed, not instant) contains about 100–150 mg of caffeine.

On each of five different days, the volunteers (26 healthy young adults) took one of these guaraná doses, or a placebo, immediately after a baseline test of cognitive function and mood. Saliva samples were obtained at the outset of each day’s testing to ensure that the subjects had complied with the study’s take-no-caffeine rule (it turned out that five had not complied, so their data were discarded, leaving 21 data sets). The researchers tested the volunteers again 1 hour, 3 hours, and 6 hours after the treatment.

. . . Which Are Probably Not Due to the Caffeine

The results showed a significant improvement in only one of the five domains of cognitive function: secondary memory (which consisted of delayed word recognition, delayed picture recognition, immediate word recall, and delayed word recall tasks). Interestingly, improvements were seen only for the two lowest doses of guaraná. By contrast, the results for alertness in the mood-assessment test showed a significant improvement only for the highest dose. For contentedness, there were improvements with all four doses, and for calmness, there were none.

This mixed bag of results led the researchers to one primary conclusion: whatever it was in guaraná that was causing the modest improvements in cognitive function and mood, it was probably not the caffeine, because the amounts were not high enough to account for the effects observed. Other components are probably responsible, at least in part. Again, the call was for further research, preferably including tests with decaffeinated guaraná.

Practice, and Supplement

Quick—what day of the week was September 25, 1948? What, you can’t figure that out in your head in a couple of seconds? Don’t despair—you don’t really need that skill. You may never be a Raymond Babbitt at arithmetic, but you can improve the skills you do have by practicing them and, perhaps, by taking a few nutritional supplements that can give your mind an extra edge.

(It was a Saturday—I had to look it up.)


  1. Reay JL, Kennedy DO, Scholey AB. Effects of Panax ginseng, consumed with and without glucose, on blood glucose levels and cognitive performance during sustained ‘mentally demanding’ tasks. J Psychopharmacol 2006 [online preprint].
  2. 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.
  3. Haskell CF, Kennedy DO, Wesnes KA, Milne AL, Scholey AB. A double-blind, placebo-controlled, multi-dose evaluation of the acute behavioural effects of guaraná in humans. J Psychopharmacol 2006 [online preprint].
  4. Kennedy DO, Haskell CF, Wesnes KA, Scholey AB. Improved cognitive performance in human volunteers following administration of guaraná (Paullinia cupana) extract: comparison and interaction with Panax ginseng. Pharmacol Biochem Behav 2004;79:401-11.

Phosphatidylserine Boosts Exercise Capacity

One might not expect that a supplement known for its ability to enhance memory and reduce mental and emotional stress could also boost physical energy. That, however, seems to be the case with phosphatidylserine, a fatty compound found mainly in our cell membranes, along with phosphatidylcholine and a few other phospholipids.

Although the phosphatidylserine (PS) molecule is found in the cell membranes of all tissues, it is most concentrated in organs with high metabolic activity, such as the brain, heart, skeletal muscles, and liver. There it plays a variety of physiological roles that have the potential to influence certain enzymatic functions in our mitochondria, the tiny biochemical “powerhouses” where cellular energy metabolism occurs. This realization led a group of researchers in Wales and Ireland to study the effects of PS supplementation on exercise capacity in 14 healthy young men.1

Under controlled laboratory conditions, the men exercised at various set levels of effort (as measured by the percentage of their maximal oxygen uptake) on stationary exercise bikes rigged to measure work output. With placebo, there was no change in exercise capacity from the baseline test to the treatment test (16 days apart, with 10 days on placebo). With a 750-mg dose of phosphatidylserine, however, the men’s time to exhaustion at 85% of maximal oxygen uptake (very heavy exercise) increased significantly, from 7.9 minutes at baseline to 9.9 minutes 16 days later (with 10 days on PS)—a 25% increase.

The researchers concluded,

This is the first study to report improved exercise capacity following phosphatidylserine supplementation. These findings suggest that phosphatidylserine might possess potential ergogenic properties.

(Ergogenic means tending to increase work output.)


  1. Kingsley MI, Miller M, Kilduff LP, McEneny J, Benton D. Effects of phosphatidylserine on exercise capacity during cycling in active males. Med Sci Sports Exerc 2006;38:64-71.

Will Block is the publisher and editorial director of Life Enhancement magazine.

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