I've been conducting experiments on myself for the past few months. I would take only one supp before bed for a week at a time and test the morning wood.
So far, maca and avena are the only two that never let me down. But I havn't found any research on maca decreasing SHBG. (but curiously, it's been shown to stimulate the thyroid) so it's libido enhancing effects are probably working on a different pathway.It's effects seem to carry throughout the day.
However, there are several studies, albiet sketchy, that suggest Avena directly lowers SHBG. I also find that I get some acne with the avena, which also suggests more free T. The erections also seem stronger and last longer with Avena. I swear, it's like I got a baseball bat touching my chin, under my sheets. I'm sold on it but fear the price going up an the quality going down.
For futher edification, here are my conclusions regarding other pro-sexual compounds. All opinions are welcome.
Tribulus: Intensifies the rigidity of an erection, almost to the point of it being numbing, but does not increase libido or morning wood. It's doubtful that it increases T, free or otherwise.
Epimedium: Seems to stimulate desire, but this is too intangible to determine with any certainty. Has no effect on morning wood.
Arginine: Works to produce NO2, which is what Viagra does. Add 2 grams of Arginine to your normal dose of Viagrra for an extra "kick." By itself, it does nothing.
Nettles: To close to call. It lowers SHBG, but also lowers DHT, which makes it a wash in regard to a sexual aide. Also lowers prolactin, making it the ideal BPH herb. But I hate supressing DHT. It's good to me.
Pro-hormones: Total dick killers. I notice a little spike for a day or two ( probably from the boost in estrogen) , then I'm a eunich for a month. Never again.
Carao: I will giving this the acid test soon. I stopped taking it for a while so I should be clear. I have to stop the avena (sob) and I know the wake up wood will go away. (I'm 49) I will then take ONLY Carao for 2 weeks and see if my one eyed pal perks up. THis is a crude method for testing SHBG, I know, but it's pretty damn accurate -- short of monthly blood tests, both with and without the substance in your system.