In 2008 Nigerian researchers wrote about the African herb Massularia acuminata, [J Ethnopharmacol. 2008 Aug 13;118(3):508-13.] which according to Nigerian studies boosts testosterone levels. Meanwhile, four years on, Massularia acuminata is found in an increasing number of supplements. And they may well be effective, if new studies are anything to go by. In high doses.
The reason that supplements manufacturers are so interested in extracts of plants such as Massularia acuminata is the following: the market for designer steroids is under threat. For years supplements makers have trawled the biochemical literature in search of interesting but hitherto unmarketed oral anabolic steroid hormones, which they then added to their products. These were of course forbidden in the EU, but even there they found their way to adventurous consumers via the internet.
The era of the designer steroids is now over. In the US bodies such as the FDA have hunted down producers and sellers of designer steroids. So what's the alternative to designer steroids? Plant extracts, such as Massularia acuminata, which traditional healers have been using for centuries to treat impotence, reduced libido and infertility, and which according to modern research boost testosterone levels.
The 2008 animal study really only indicated that Massularia acuminata boosted testosterone levels and made the testes grow. The authors of the study, working at the University of Ilorin in Nigeria, later published a number of animal studies which showed that Massularia acuminata given to male rats stimulated sexual behaviour.
In 2011 for example, the Nigerians published the results of a study in Evidence-Based Complementary and Alternative Medicine. For this they had given male rats a daily 250, 500 or 1000 mg of Massularia acuminata extract for a period of five days. During this period the rats' testosterone level and sexual interest increased.
When the researchers introduced the male rats to sexually active females, the longer the rats had been taking supplements the often they mounted the females [Mount frequency]. They also ejaculated more frequently [Ejaculation frequency]. The effect was stronger the more Massularia acuminata the rats had had.
So it looks as though Massularia is effective. We do need to bear in mind that all animal studies on the effects of Massularia acuminata were performed by the same group of Nigerians. On the other hand, the Nigerians were not paid by a supplements manufacturer but by the IFS. [ifs.se]
If you convert the doses used into ones suitable for humans, you come up with 40-160 mg rutin per kg bodyweight per day. If you weight 80 kg, then you'd need to take between 3.2 and 12.8 g Massularia-extract per day. Using somewhat more conservative methods of calculation you arrive at 2-8 g extract per day.
Evid Based Complement Alternat Med. 2011;2011:738103.