Bulbine natalensis is a succulent plant native to South Africa that has gained interest in the supplement market for its purported effects on testosterone levels. The traditional use of this plant has included various applications in folk medicine, but its reputation as a testosterone booster is primarily based on recent animal studies rather than long-standing traditional practices.

Scientific evidence supporting Bulbine natalensis for testosterone support is limited and mostly confined to preclinical research. A handful of studies in rats have shown that extracts of Bulbine natalensis can increase serum testosterone levels, sometimes accompanied by increases in luteinizing hormone, and may have effects on sexual behavior. For example, a study by Yakubu and Afolayan (2010) found that Bulbine natalensis extract increased testosterone in male rats, but also noted potential adverse effects at higher doses, including liver and kidney toxicity.

There are no published human clinical trials investigating its effects on testosterone levels, libido, or related endpoints. Therefore, while the ingredient is justified for use based on preliminary scientific studies in animals, there is currently insufficient evidence to support its effectiveness or safety in humans. The overall quality and quantity of evidence is low, justifying a moderate-to-low evidence rating.