Effects of Herbal Preparation on Libido and Semen ... [Reprod Domest Anim. 2010] - PubMed result

There are many positive research results about tongkat ali: but mostly on male rats. Here is a study on boars.
Although boars are still not human, boars are much more similar to human than rats especially in size. Among all mammals, boars are also similar to men in sense of sex frequency. It's much easier to estimate libido and semen volume on boars than on men.

Anyway, the result is, boars which took herbs got a 20% boost in libido (boars are horny creatures already) and about 30% increase in semen volume, also less abnormal sperms.