11-Ketotestosterone (11-KT) is a potent androgen primarily found in fish and some non-mammalian vertebrates. In these species, it is a key hormone for male sexual development and reproductive function, often surpassing testosterone itself in its androgenic effects. In humans, 11-KT is present at low levels and is considered a metabolite of adrenal androgens. Its physiological role in humans is less clear, but recent scientific research has begun to uncover its significance in specific contexts.

Studies have shown that 11-KT can activate the human androgen receptor with similar potency to testosterone. It has been investigated as a biomarker for certain disorders of androgen excess, such as congenital adrenal hyperplasia and polycystic ovary syndrome (PCOS). However, its direct use as a supplement or treatment to support or enhance the testosterone system in humans is not established practice and is not approved for clinical use. Research in fish models has validated its importance for male reproductive health, but the translation of these findings to human supplementation or therapy remains scientifically limited.

In summary, 11-Ketotestosterone has a scientifically validated role as an androgen, particularly in non-human species, and evidence supports its biological activity in humans. Nevertheless, direct scientific evidence supporting its supplementation to enhance or support the testosterone system in humans is currently limited, and more research is needed to clarify its potential utility.