Wednesday January 9 2013
Ginseng extract is alleged to be an aphrodisiac
“Forget Viagra, a tablet made from ginseng could boost a man's love life” is the excitable, but misleading headline, in the Daily Mail.
The headline was based on a randomised control trial which compared two groups of 59 men with mild-to-moderate erectile dysfunction, one group was given a ginseng extract pill for eight weeks and the other a placebo pill for the same period.
The study actually found that ginseng did not improve sexual dysfunction more than placebo across the vast majority of areas tested, which included:
- erectile function
- intercourse satisfaction
- orgasmic function
- sexual desire
- overall sexual satisfaction
The only exception was ejaculation function (the ability to adequately delay ejaculation during sexual intercourse), which was statistically better than placebo, but the improvement was still very modest – just a one to two point improvement on a 0 to 20 scale.
Also, it was not clear whether this small improvement was either important clinically or to the men themselves.
Similarly, as the study recruited only men with erectile dysfunction and aimed to treat them, measuring ejaculation dysfunction was of secondary interest.
While the study itself was well designed (a double-blinded, placebo controlled, randomised control trial – the ‘gold standard’ of medical research), the researchers’ overstated the implications of their results
Unfortunately, the media then repeated these claims unchecked. This should remind readers that media claims relating to health research often do not stand up to scrutiny.
Where did the story come from?
The study was published in the peer-reviewed International Journal of Impotence Research.
The study was carried out by researchers from South Korea and was funded by a grant from the Korean Ministry for Health and Amorepacific – a manufacturer of health and beauty products, including some containing ginseng. While there were no conflicts of interest declared by the study authors, there is a clear potential conflict of interest between Amorepacific’s commercial interests and the impartial nature of the research.
However, the involvement of the company in the research was not described; consequently it is not possible to assess the degree to which the research may have been biased by the commercial interests, if at all.
The Mail’s coverage did not question the overly positive reporting of the study results by the research authors it merely repeated it.
Similarly, its statement that “men with erectile dysfunction improved their performance in the bedroom after taking the tablets for just a few weeks” is misleading as both groups – those given ginseng and those given placebo – improved. In fact, ginseng was shown to be no more effective than the dummy pill for erectile dysfunction.
What kind of research was this?
This was a multi-centre, placebo-controlled, double-blind randomised control trial looking at the effectiveness and safety of using an extract of ginseng berry to treat sexual dysfunction in men.
Male sexual dysfunction covers a wide range of problems, of which the two most common are:
- erectile dysfunction
- premature ejaculation
Both conditions can have a severe impact on the quality of life for affected men. The researchers highlight that ginseng extract is particularly common and widely used in Asian countries because of its alleged properties of boosting the immune system, and of “providing vigour and enhancing sexual activity”.
A randomised control trial such as this is one of the best ways to assess whether a new medicine or extract is effective. The randomisation process ensures that other potentially influential factors are evenly balanced between the treatment and control groups.
What did the research involve?
In all, 119 South Korean men with mild-to-moderate erectile dysfunction participated in this multicentre, randomised, double-blind, parallel, placebo-controlled clinical study (though one man dropped out after study start). The men had suffered from erectile dysfunction for a period of three or more months, and were aged between 20 and 70 years old.
All the participants were married and agreed to make at least four attempts a month at sexual intercourse with their spouse.
The men were given four tablets of either standardised Korean ginseng berry (350mg ginseng berry extract per tablet), or placebo (n=59 in each group), daily for eight weeks. Placebo and ginseng tablets were identical in appearance.
Erectile dysfunction was the primary outcome and was assessed at the end of the fourth and eighth weeks using a single domain of the International Index of Erectile Function (IIEF)-15. The IIEF-15 is a questionnaire, consisting of 15 questions related to erectile function and sexual satisfaction.
The answers are then used to generate a score which can range from 15 (meaning no sexual activity is taking place due to erectile dysfunction) to 75 (meaning sexual activity is entirely, or almost entirely, unaffected by erectile dysfunction).
Other domains on this index included intercourse satisfaction, orgasmic function, sexual desire and overall satisfaction. Premature ejaculation was also assessed using a separate diagnostic tool (PEDT), which works in a similar manner to the IIEF-15. A PEDT score can range from 0 to 20 with a score of 11 or more broadly indicating men who may have a problem with ejaculating too soon during sexual activity.
Baseline parameters, cholesterol levels and hormonal status, including total testosterone and prolactin, were measured at the beginning and the end of the study. Clinical information and trial data were collected during individual interviews at 0, 4 and 8 weeks by a trained interviewer.
All participants, investigators, pharmacists and study personnel were blinded to treatment allocation.
The statistical analysis was appropriate and used intention to treat data where possible.
What were the basic results?
On average, erectile function improved slightly in the ginseng group from a baseline score of 17.17 (standard deviation [SD]±2.57) to 18.59 (SD±5.99) by the eighth week, which was a statistically significant increase (p=0.046). However, the placebo group also improved and the difference in improvement between the ginseng and placebo groups was only borderline significant (p=0.501). This means there may be no significant advantage of using ginseng over placebo for erectile function.
The premature ejaculation score improved in the ginseng group from 9.14 (SD±4.57) to 7.53 (SD±4.26) after eight weeks. Unlike all the other results, this on eto two point improvement was significantly better than the effect seen in placebo which improved from 10.46 (SD±4.79) to 9.66(SD±4.57) during the same period (p=0.017).
Other areas of sexual function
All other individual areas tested (intercourse satisfaction, orgasmic function, sexual desire and overall satisfaction) improved by small amounts in the ginseng group, all of which were statistically significant increases. However, none of the improvements seen using ginseng were significantly different from those seen using placebo. This suggests taking ginseng was no better than taking the dummy pill.
No significant changes in hormones, cholesterol levels in the blood, or other blood chemistry measures to assess safety were observed in either of the groups or between the start and end of the study.
This suggests that any observed effect may not be related to hormones or cholesterol levels.
How did the researchers interpret the results?
The researchers concluded that “oral administration of the SKGB [ginseng] extract improved all domains of sexual function. It can be used as an alternative medicine to improve sexual life in men with sexual dysfunction.” They also stated that “Korean ginseng berry treatment was both efficacious and well tolerated in men with mild-to-moderate ED [erectile dysfunction]”.
This randomised control trial comparing 59 men taking ginseng extract pills to 59 men taking placebo pills for eight weeks found that ginseng did not improve sexual dysfunction more than placebo across a range of areas (erectile function, intercourse satisfaction, orgasmic function, sexual desire and overall sexual satisfaction). Those taking ginseng showed a small but significant improvement in erectile dysfunction score compared to those on a placebo dummy pill.
The research authors’ conclusions put an overly positive spin on the results of this well designed study. They concluded that “oral administration of the SKGB [ginseng] extract improved all domains of sexual function” but neglect to mention that in all domains, barring premature ejaculation, this improvement was no better than taking a dummy placebo pill. This is a very crucial and arguably disingenuous omission.
As is often the case with studies using scales and scores to assess a condition, it is difficult to assess the magnitude of the impact this has on a person’s life.
For instance, do the men registering the small one or two point improvement in ejaculation function actually notice their condition has improved, do they feel more confident, or is this change too small to notice? A one to two point improvement, in terms of the PEDT diagnostic tool, could represent only a very modest improvement, such as moving from being extremely frustrated due to premature ejaculation to being very frustrated due to premature ejaculation.
Answering this question would require more information about the men’s perceptions of their condition and that is difficult to establish using this published research alone.
To be fair, the researchers recognised this point, describing how a “1.5-point change could be considered clinically dubious for recommending SKGB [ginseng] as a drug”.
One of the strengths of this trial was that it detailed precisely the ginseng strength and type used to make the pill. However, readers should not assume that all ginseng extracts are the same or will have similar effects (or lack of effect). Complementary medicines can often vary in what they contain, despite having similar or identical names; this will affect their potential medicinal properties and safety.
Sexual satisfaction or dissatisfaction is a multi-faceted and complex area that has both social and physical components. This study primarily tested the effect of taking ginseng pills for eight weeks in Korean men with mild to moderate erectile dysfunction. Using different strengths of ginseng, treating the men for different periods, treating different severities of erectile dysfunction and men of different ethnicities may influence the findings if they were repeated in other groups and situations. Similarly, no specifically social aspects of sexual dysfunction were assessed in this study, which may have influenced the results if considered.
Based on this study alone we can reasonably conclude that the ginseng pill tested was no better than placebo at improving most domains of sexual dysfunction (including erectile dysfunction) in men given it for eight weeks.
The exception was ejaculation function which improved by a small amount, that was statistically better than placebo, but this was not the primary condition for which men were enrolled.
It is debatable whether the modest improvement seen in ejaculation function would be more effective than current conventional treatments for premature ejaculation. No direct comparison of current treatments for premature ejaculation versus ginseng tablets was attempted in this study.
Further research will need to replicate this study to confirm or refute these findings.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.