Pumpkin Seed
Cucurbita pepo
Evidence Rating
C Moderate
Confidence Level
Moderate
Medium
Traditions
Western
Last Updated
2/9/2026
Summary
Pumpkin seed (Cucurbita pepo) is a well-tolerated European phytotherapeutic approved by Commission E for irritable bladder and BPH stages I-II. The landmark GRANU study (n=1,431) demonstrated clinically relevant IPSS reduction vs. placebo over 12 months. Its mechanism involves anti-androgenic, anti-inflammatory, and cholesterol metabolism effects. Exceptionally safe for long-term use, it occupies a unique niche as a mild, food-grade BPH treatment that patients can incorporate into their diet as whole seeds or take as standardized extracts.
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Drug Interactions
This herb has significant drug interactions. Do not use if you are taking medications without consulting a healthcare provider first. See detailed interaction information below.
Regulatory Status
| Regulatory Body | Status |
|---|---|
| Commission E (Germany) | âś“ Approved |
| ESCOP (European) | âś“ Approved |
| EMA/HMPC (EU) | âś“ Approved |
Metadata
| Field | Details |
|---|---|
| Common Names | Pumpkin Seed (EN), Kuerbissamen (DE) |
| Botanical Name | Cucurbita pepo L. |
| Plant Family | Cucurbitaceae (Gourd/Squash family) |
| Part Used | Seed (semen) and seed oil |
| Drug Name | Cucurbitae semen |
| Evidence Quality Rating | Moderate |
Approved Indications
Commission E (Germany)
- Approved (first published 1985, revised 1991):
- Irritable bladder (Reizblase)
- Micturition complaints associated with prostate adenoma stages I and II
- Note: Commission E states “This remedy brings about only relief of the symptoms of the prostate adenoma without reducing the enlargement of the prostate”
ESCOP
- Approved: Symptomatic treatment of micturition disorders:
- Painful urination
- Frequent urination
- Nocturnal urge to urinate
- Urinary retention and residual urine formation
- In connection with BPH stages I-II or irritable bladder
EMA/HMPC
- Traditional Use: Based on long-standing use for relief of LUTS related to BPH and for irritable bladder
- Community herbal monograph published on Cucurbita pepo L., semen
Agreement/Disagreement
- Good agreement between Commission E, ESCOP, and EMA/HMPC on therapeutic scope
- All European bodies acknowledge symptomatic relief only (no effect on prostate size)
- US: Not widely recognized; limited awareness compared to saw palmetto
- Evidence rated lower than saw palmetto but higher than birch leaf or horsetail
Conditions Treated
- Benign prostatic hyperplasia (BPH) stages I-II — symptomatic relief
- Irritable bladder (overactive bladder symptoms)
- Lower urinary tract symptoms including:
- Nocturia
- Pollakisuria
- Dysuria
- Urinary retention
- Residual urine formation
Mechanism of Action
Primary Mechanisms
-
Anti-Androgenic Activity
- Inhibition of 5-alpha-reductase enzyme activity
- Reduction in DHT-mediated prostate cell proliferation
- Delta-7-sterols (specific to Cucurbita species) may compete with DHT at receptor level
-
Alteration of Cholesterol Metabolism
- Phytosterols (particularly delta-7-sterols unique to pumpkin seeds) interfere with cholesterol metabolism in prostate tissue
- May reduce prostate cell membrane cholesterol content
-
Anti-inflammatory Effects
- Inhibition of inflammatory cascades in prostate tissue
- Reduction of prostaglandin synthesis
-
SHBG Modulation
- Decrease in available sex hormone-binding globulin (SHBG)
- May alter free testosterone/DHT ratios
-
Smooth Muscle Relaxation [UNCERTAIN]
- Some evidence for relaxation of bladder neck and prostate smooth muscle
- May explain efficacy in irritable bladder beyond BPH
Key Bioactive Compounds
- Delta-7-sterols: Delta-7-stigmastenol, delta-7-avenasterol (unique to Cucurbita species; proposed key active compounds)
- Phytosterols: Beta-sitosterol, campesterol
- Essential fatty acids: Linoleic acid, oleic acid (in seed oil)
- Tocopherols: Vitamin E (particularly gamma-tocopherol)
- Zinc: High zinc content (potentially relevant to prostate health)
- Selenium: Trace mineral content
- Carotenoids: Including lutein
Clinical Evidence Summary
GRANU Study (German Research Activities on Natural Urologicals)
- Design: Randomized, partially blinded, placebo-controlled trial
- Sample Size: n=1,431 men (ages 50-80)
- Duration: 12 months
- Groups:
- Pumpkin seed (5g twice daily)
- Pumpkin seed extract capsule (500mg twice daily, Granu Fink prosta forte)
- Placebo
- Results:
- Pumpkin seed group: 58.5% response rate
- Placebo group: 47.3% response rate
- Clinically relevant IPSS reduction vs. placebo over 12 months
- Both whole seed and extract forms showed benefit
- Significance: Largest trial of pumpkin seed for BPH; statistically significant but modest effect
- [Source: Urol Int. 2015;94(3):286-95]
Pumpkin Seed Oil vs. Tamsulosin
- Design: Single-blind randomized clinical trial
- Result: Pumpkin seed oil relieved BPH symptoms with no side effects, but was not as effective as tamsulosin
- Dose: 360mg pumpkin seed oil twice daily
- [Source: BMC Urology, 2021]
Combination Studies
- Pumpkin seed oil + saw palmetto oil studied in Korean men with BPH (Park et al., 2009)
- Pumpkin seed extract + soy germ extract for overactive bladder (double-blind RCT)
- Generally positive results in combination contexts
Evidence Limitations
- The GRANU study, while large, showed modest effect sizes
- Few large-scale confirmatory RCTs
- Heterogeneity in preparations studied (whole seeds vs. oil vs. dry extract)
- Standardization challenges across products
European vs US/Anglophone Consensus
| Aspect | European Position | US/Anglophone Position |
|---|---|---|
| Regulatory status | Commission E approved; EMA traditional use | Dietary supplement only |
| Clinical use | Commonly recommended by urologists/GPs; widely used in Germany | Limited awareness; not commonly recommended |
| Products | Granu Fink (leading German brand); pharmaceutical quality | Various supplements; less standardization |
| Cultural status | ”Steirisches Kuerbiskernoel” (Styrian pumpkin seed oil) is a culturally valued food-medicine in Austria/Southern Germany | Pumpkin seeds known as health food but not specifically for prostate |
| Evidence perception | Accepted based on Commission E + GRANU study | Considered insufficient; “more research needed” |
Safety Profile
Contraindications
- No specific contraindications identified
- Known hypersensitivity to Cucurbita species (rare)
Drug Interactions
- Lithium: May decrease lithium excretion due to potential diuretic effect; dose adjustment may be needed
- No other significant drug interactions documented
- Exceptionally safe in terms of drug-interaction profile
Side Effects
- Very rare: Mild gastrointestinal discomfort
- Essentially food-safe: Pumpkin seeds are a common food item with an excellent safety record
- No serious adverse effects reported in clinical trials
- The GRANU study confirmed good tolerability over 12 months
Pregnancy/Lactation
- No specific contraindication at food-level doses
- Medicinal doses: Insufficient data; standard precautionary avoidance recommended
- Whole pumpkin seeds are generally consumed freely during pregnancy as food
Clinical Dosage
Standardized Dosage Forms
| Form | Dosage | Notes |
|---|---|---|
| Whole pumpkin seeds | 10g daily (5g twice daily) | Used in GRANU study; can be incorporated into diet |
| Pumpkin seed extract capsules | 500-1000 mg daily | Granu Fink prosta forte uses 500mg b.i.d. |
| Pumpkin seed oil | 320-480 mg daily (in divided doses) | Soft gelatin capsules |
| Combination products | 480mg oil + saw palmetto | Various formulations |
Key Standardized Products
- Granu Fink Kuerbiskerne (Omega Pharma, Germany): 10g whole purified pumpkin seeds daily
- Granu Fink prosta forte (Omega Pharma, Germany): 500mg pumpkin seed extract capsules b.i.d.
- Prosta Fink forte (GSK, Germany): Pumpkin seed extract
- Curbicin (combination pumpkin seed + saw palmetto)
Duration of Treatment
- Minimum 3 months for initial assessment
- Suitable for long-term/indefinite use given food-grade safety profile
- No maximum duration established
Sources
- EMA Assessment Report on Cucurbita pepo semen
- EMA Community Herbal Monograph on Cucurbita pepo
- GRANU Study — Urol Int. 2015 (PubMed)
- Pumpkin Seed Oil vs. Tamsulosin (BMC Urology)
- Cucurbita pepo and BPH — Narrative Review
- Altmeyers Encyclopedia — Cucurbitae semen
- Effects of Oil-Free Pumpkin Seed Extract on BPH (J Med Food)
Connections
- See Saw Palmetto for the strongest-evidence BPH herb (often combined)
- See Nettle Root for another BPH combination partner
- See Pygeum for an alternative BPH herb with different mechanism