Benefits
Prostate and urinary comfort in men
In a 12-month double-blind trial in 47 men with an enlarged prostate, 320 mg a day of pumpkin seed oil lowered prostate symptom scores and raised urine flow versus baseline, but not significantly more than placebo. In a one-year trial of 1,431 men, whole pumpkin seed gave more responders than placebo, while a seed extract did no better than placebo.
Urinary frequency and bladder comfort
In an uncontrolled 12-week study of 45 adults with overactive bladder, 10 g a day of oil from a different species, Cucurbita maxima, lowered bladder symptom scores. A 12-week observational study in 117 women used pumpkin seed oil combined with fragrant sumac and hop extracts, so it does not isolate pumpkin seed oil.
Hair growth in men with pattern hair thinning
In a 24-week randomized, double-blind, placebo-controlled trial of 76 men with mild to moderate androgenetic alopecia, 400 mg a day of pumpkin seed oil raised mean hair count by 40 percent versus 10 percent with placebo, and men rated their improvement higher. Side effects did not differ from placebo. It is one trial.
Mechanism of action
5-alpha-reductase activity (animal data)
In rats with testosterone-driven prostate enlargement, a sterol fraction from hull-less pumpkin seed oil, made up mostly of delta-7 sterols, reduced prostate enlargement and lowered 5-alpha-reductase and androgen receptor expression. This has not been measured in people taking the oil.
Plant sterol content
Pumpkin seed oil supplies plant sterols, mainly delta-7 sterols in hull-less seed, along with beta-sitosterol. These sterols are the compounds usually proposed to explain its prostate and hair effects, but human mechanism studies are lacking.
Clinical trials
Randomized, double-blind, placebo-controlled trial of 400 mg/day pumpkin seed oil or placebo for 24 weeks (Cho et al. 2014, Evid Based Complement Alternat Med)
76 men with mild to moderate androgenetic alopecia
Mean hair count rose 40% with pumpkin seed oil versus 10% with placebo (P < 0.001), and self-rated improvement and satisfaction scores were higher than placebo. Adverse effects did not differ between groups.
Randomized, double-blind, placebo-controlled 12-month trial with four arms: placebo, pumpkin seed oil 320 mg/day, saw palmetto oil 320 mg/day, or both (Hong et al. 2009, Nutr Res Pract)
47 Korean men with benign prostatic hyperplasia (average age 53.3) and prostate symptom scores above 8
In the pumpkin seed oil group, prostate symptom score fell from 20.7 to 8.7 and peak urine flow rose from 14.8 to 17.0 mL/s over 12 months versus baseline. The authors report no statistically significant differences between groups for any measure at any time point, so the trial did not show a benefit over placebo.
Randomized, partially blinded, placebo-controlled 12-month trial of whole pumpkin seed 5 g twice daily, pumpkin seed extract capsules 500 mg twice daily, or placebo (Vahlensieck et al. 2015, Urol Int)
1,431 men aged 50 to 80 with lower urinary tract symptoms from benign prostatic hyperplasia
The responder rate (a drop of 5 or more points in prostate symptom score) did not differ between seed extract and placebo. Whole seed gave 58.5% responders versus 47.3% with placebo, which the authors call descriptively significant and say needs confirmation. The trial tested seed and an extract, not the oil.
Uncontrolled single-group study of 10 g/day oil from Cucurbita maxima seeds for 12 weeks (Nishimura et al. 2014, J Tradit Complement Med)
45 adults with overactive bladder
Overactive Bladder Symptom Score fell significantly at 6 and 12 weeks versus baseline. There was no placebo group, and the oil came from a different species than Cucurbita pepo.