Capsaicin keeps your testosterone level up

A low-calorie diet drives testosterone production down, a real nuisance for natural athletes who not only want to decimate their fat reserves but also maintain their lean body mass. Supplementing with capsaicin – and perhaps analogues too – may offer hope, according to a Turkish animal study.

Researchers at the University of Uludag in Turkey have been studying the effects of capsaicin (the compound which gives peppers their hot taste) on hormonal regulation for a number of years. The researchers discovered that chickens’ sex organs develop faster if they are given capsaicin in their feed. [Phytother Res. 2005 Jun;19(6):501-5.] This may be because the animals start to make more LH and FSH, the Turkish researchers discovered, but it may also be that there is a direct effect on the sexual organs. [J Food Agr Envir 2006;4:119–23.] In mice it also seems that injections of 1 mg capsaicin per kg bodyweight stimulates the development of sperm. [Veterinarski Arhiv 01/2009;79:509-516.]

Capsaicin attaches itself to VR1 receptors, which are located in the brain, but are also found in hormone producing cells in the testes. In the animal study that the Turks are about to publish in Biotechnic and Histochemistry, they test the theory that capsaicin sabotages the effect of the hormone ghrelin.

The stomach and the pancreas produce ghrelin if we eat little or nothing. Ghrelin is a ‘hunger hormone’, which is released in large quantities during a weight-loss diet. It stimulates the secretion of growth hormone through the growth hormone secretagogue receptors, but also inhibits the secretion of testosterone. This happens partially via a ghrelin receptor in the testes. The researchers wanted to know whether capsaicin could diminish ghrelin’s inhibitory effect on testosterone.

And you find studies that tell you what you already knew: that you recover faster from a weight training session if you build it up in the correct way, only starting on heavy sets once you’ve prepared your body. [J Sports Sci. 1997 Oct;15(5):477-83.]

They gave 40-day-old adolescent male mice and 75-day-old adult mice food consisting of 0.02 percent capsaicin. In the adult mice in particular capsaicin raised the concentration of testosterone in the blood, as you can see in the graph below on the right. The ghrelin concentration rose too, as shown below on the left.

But in the testosterone producing Leydig cells in the testes of the mice that had been given capsaicin the researchers found less ghrelin. Apparently capsaicin suppresses the uptake – and thus the effect – of ghrelin in those cells.

So capsaicin may be a candidate for a testosterone booster during a slimming diet. The dosage may be a bit of a problem. According to our most conservative estimate, the human equivalent of the doses the Turks used would be several hundred milligrams per day. That’s too high for a normal human. Luckily there are also capsaicin analogues which have fewer side effects, and which according to a Japanese study also interact with the same receptor. One is dihydrocapsiate. Now, if this works as well as capsaicin…

A second alternative might be evodiamine. This compound also interacts with the same receptor as capsaicin does.

Capsaicin, capsiate and evodiamine all help weight loss by the way, so they’re also interesting if you’re following a weight-loss diet.