Fenugreek (Trigonella foenum-graecum) has published evidence for free testosterone support via 5α-reductase inhibition. Complete guide to the evidence and correct dose.
Fenugreek seed extract at 500-600mg daily has published evidence for supporting free testosterone levels. The mechanism involves inhibition of aromatase and 5α-reductase — enzymes that convert testosterone to oestrogen and DHT respectively. Published RCTs confirm increases in free testosterone in healthy men.
Fenugreek (Trigonella foenum-graecum) contains protodioscin — a steroidal saponin that appears to inhibit aromatase and 5α-reductase activity, reducing the conversion of testosterone to oestrogen (aromatase) and DHT (5α-reductase). This preserves free testosterone rather than increasing total testosterone production.
Wilborn et al. (2010) found fenugreek extract at 500mg daily significantly increased free testosterone and maintained total testosterone in resistance-trained men over 8 weeks, compared to placebo which showed decreases. A separate study (Steels et al., 2011) found significant improvements in libido and wellbeing alongside testosterone support.
Testosil® contains fenugreek seed extract at 600mg — at or above the doses used in published trials — as part of its comprehensive testosterone support formula.