I know some people here are trying to raise testosterone and have even asked Peat about it. Peat responded long the lines of "increase vitamin A and thyroid". It looks like he is right (again) about the vitamin A part. This study shows that both retinol and retinoic acid stimulated testosterone production but surprisingly retinol was more effective, whatever that may mean. I will try to get the full study tomorrow and get some numbers on dosage that can reach the in-virto concentrations used in this study.
http://www.ncbi.nlm.nih.gov/pubmed/2916988
"...Adult rat Leydig cells, purified by Percoll density gradient centrifugation, were used to determine the effect of retinol and retinoic acid on steroidogenesis. It was found that both retinoic acid and retinol stimulated testosterone production. Although retinol was less potent than retinoic acid, retinol had the greater efficacy. When these retinoids were tested in the presence of a maximal dose of LH, it was found that retinol inhibited LH-stimulated testosterone synthesis whereas retinoic acid had no similar effect. These results demonstrate for the first time that retinol and retinoic acid have a direct effect on Leydig cell steroidogenesis in culture suggesting that retinoids play a role in the maintenance and regulation of Leydig cell function."
http://www.ncbi.nlm.nih.gov/pubmed/2916988
"...Adult rat Leydig cells, purified by Percoll density gradient centrifugation, were used to determine the effect of retinol and retinoic acid on steroidogenesis. It was found that both retinoic acid and retinol stimulated testosterone production. Although retinol was less potent than retinoic acid, retinol had the greater efficacy. When these retinoids were tested in the presence of a maximal dose of LH, it was found that retinol inhibited LH-stimulated testosterone synthesis whereas retinoic acid had no similar effect. These results demonstrate for the first time that retinol and retinoic acid have a direct effect on Leydig cell steroidogenesis in culture suggesting that retinoids play a role in the maintenance and regulation of Leydig cell function."