Benefits
Testosterone support in men with low levels
In a 12-week placebo-controlled trial in 105 men aged 50 to 70 with testosterone below 300 ng/dL, 200 mg a day of the Physta extract raised total testosterone more than placebo at weeks 4, 8 and 12, and 100 mg a day did so at week 12. Free testosterone did not differ from placebo. The maker funded the trial.
Stress and cortisol modulation
In a 4-week placebo-controlled trial in 63 moderately stressed adults (32 men and 31 women), 200 mg a day of the Physta extract lowered salivary cortisol by 16% and raised salivary testosterone by 37%, with lower tension, anger and confusion scores. The trial was small, short and funded by the extract maker.
Energy and well-being
In the 12-week trial in men aged 50 to 70, fatigue and ageing male symptom scores improved more than with placebo. In a 12-week trial in men aged 30 to 55, the physical functioning part of a quality of life survey improved more than with placebo. Both outcomes were self-reported, and the maker funded both trials.
Erectile function scores
In a 12-week placebo-controlled trial in 109 men aged 30 to 55, most with no or mild erectile dysfunction, 300 mg a day of Physta raised the erectile function score more than placebo, from about 25.4 to 26.8 points. Mean libido scores did not differ from placebo at any visit, though they rose more between weeks 6 and 12. A pooled analysis of two trials (139 men) found no significant overall effect.
Strength with and without exercise training
In a 6-month placebo-controlled trial in 45 men around age 48 with symptoms of low androgen levels, knee strength rose with exercise training alone (14%) and with training plus the extract (17%), but not with the extract alone. Symptom scores fell only in the two exercise groups. In a maker-funded trial in men aged 50 to 70, strength rose more than placebo with 200 mg a day but not 100 mg.
Semen quality
Semen analysis in 36 men from a 12-week placebo-controlled trial found no significant difference from placebo in volume, count, motility or shape. A subgroup with low starting motility improved. No cited study measured pregnancy, so there is no evidence here that tongkat ali helps fertility.
Mechanism of action
SHBG and free testosterone
One proposal is that root compounds loosen how tightly SHBG (sex hormone-binding globulin) holds testosterone. This comes from laboratory work. In the 12-week human trial, SHBG did not change and free testosterone did not differ from placebo, while total testosterone rose.
Signals from the pituitary (LH)
A second proposal is that the plant's compounds prompt the pituitary to release luteinizing hormone, which signals the testes to make testosterone. None of the cited human studies measured luteinizing hormone, so this pathway is unconfirmed in people.
Enzymes that convert testosterone
Laboratory work has looked at whether the extract slows the enzymes that turn testosterone into DHT and estradiol. This has not been shown in the cited human trials.
Clinical trials
Randomized, double-blind, placebo-controlled trial of Physta 200 mg/day versus placebo for 4 weeks, funded by the extract maker (Talbott et al. 2013, J Int Soc Sports Nutr).
63 moderately stressed adults analyzed, 32 men and 31 women.
Tension (-11%), anger (-12%) and confusion (-15%) improved, salivary cortisol exposure fell 16% and salivary testosterone rose 37% compared with placebo. The trial was small and short, men and women were mixed, and one author worked for the maker.
Randomized, double-blind, placebo-controlled multicentre trial of Physta 100 mg or 200 mg/day versus placebo for 12 weeks, funded by the extract maker (Chinnappan et al. 2021, Food Nutr Res).
105 men aged 50 to 70 with total testosterone below 300 ng/dL.
Total testosterone rose more than placebo at weeks 4, 8 and 12 with 200 mg (P<0.001 at week 12) and at week 12 with 100 mg. Free testosterone rose within groups but did not differ from placebo, and SHBG did not change. Fatigue and ageing male symptom scores improved more than placebo. Back, leg and chest strength, a secondary outcome, rose more than placebo with 200 mg (P=0.01) but not with 100 mg. No safety concerns.
Randomized, double-blind, placebo-controlled 6-month trial with four groups: control, Eurycoma longifolia alone, concurrent exercise training, and training plus the extract (Leitão et al. 2021, Complement Ther Clin Pract).
45 men (mean age 47.6) with androgen deficiency of the aging male.
Knee extension strength rose in the training (14%) and training plus extract (17%) groups; knee flexion strength rose only with training plus extract. Symptom scores fell in the two training groups. The extract-alone group showed no significant gains.
Randomized, double-blind, placebo-controlled parallel trial of Physta 300 mg/day versus placebo for 12 weeks, funded by the extract maker (Ismail et al. 2012, Evid Based Complement Alternat Med).
109 men aged 30 to 55, most with no or mild erectile dysfunction at baseline.
SF-36 physical functioning improved versus placebo (P=0.028 at week 12). The erectile function score rose more than placebo (P<0.001), from 25.4 to 26.8. Mean libido scores did not differ from placebo at any visit, though the libido score rose more than placebo between weeks 6 and 12 after an early dip in both groups. Semen analysis in 36 men showed no between-group differences. Safety tests were similar to placebo.