Scientific Name(s): Cucurbita pepo L.
Common Name(s): Acorn squash, Butternut squash, Chilacayote, Field pumpkin, Fig-leaf gourd, Pepo, Pumpkin, Squash, Yellow summer squash, Zucchini
Medically reviewed by Drugs.com. Last updated on Nov 30, 2022.
Pumpkin seeds and pumpkin juice have been evaluated in limited clinical trials for anthelmintic, CNS, and hypoglycemic effects. Pumpkin seed extracts may be useful for managing symptoms of benign prostatic hyperplasia (BPH). However, clinical trial data are lacking to recommend use of pumpkin for any indication.
Limited high-quality clinical trials exist to support therapeutic dosing.
Contraindications have not been identified.
Information regarding safety and efficacy in pregnancy and lactation is lacking. Antinutrients (eg, oxalates, cyanide, tannin) have been identified in pumpkin seeds and leaves.
None well documented.
Clinical trials report few adverse reactions. Methemoglobinemia caused by high nitrate content has been reported in infants given zucchini soup for constipation. Immunoglobulin E (IgE)–related allergy to zucchini has been reported, as well as oral allergy syndrome, nausea, diarrhea, and pruritus. Cross-reactivity to watermelon, cucumber, and other Cucurbitaceae fruits has been demonstrated.
There have been no reports of severe toxicity with the use of Cucurbita extracts. Antinutrients, including oxalates, tannins, and cyanide, have been described in the seeds and leaves.
Pumpkin is a dicotyledonous vegetable that develops long vine-like stems with trifoliate leaves and edible large, fleshy fruits. The rapid-growing plant can climb to 5 m in length. The large, yellow flowers are eaten in some Mediterranean and Mexican cultures, and the fruits are eaten worldwide. Many cultivated varieties can be found throughout the world.(Caili 2006, Tyler 1987, USDA 2021) Other members of the genus include Cucurbita digitata, Cucurbita ficifolia, and Cucurbita maxima species.
The seeds of several species of pumpkin have been used in traditional medicine for centuries. Traditionally, the seeds of the Cucurbita species are ingested as a tea or after grinding. Pumpkin seeds have been used as a vermifuge to immobilize and aid in the expulsion of intestinal worms and parasites. In some cultures, small amounts of the seeds are consumed daily as a prophylactic against worm infections. The seeds have also been used in the treatment of prostate disorders. The fleshy pulp of Cucurbita is primarily consumed as a vegetable. Pumpkin flowers have also been added to tacos or soup as a source of protein.(Caili 2006, Sotelo 2007, Tyler 1987)
Investigational interest centers on polysaccharide and pectin content, as well as the presence of triterpenoids, cucurbitan glycosides, carotenoids (including lutein and beta-carotene), and cucurmosin (a ribosome-inactivating protein).(Arima 1990, Barua 1977, Caili 2006, Hou 2008, Jaroniewska 1997, Nayab 2006, Stoianova-Ivanova 1975, Wang 2008)
Glutamic and aspartic acid, leucine, valine, phenylalanine, and tryptophan are among the amino acids identified. Phytosterols (eg, spinasterol) have been identified, as well as trypsin inhibitors.(Itokawa 1982, Sotelo 2007, Villaseñor 1996)
Lipids comprise up to 50% of the seed; approximately 30% is protein. Pumpkin seeds can be a nutritional source of iron and potassium. Phytosterols (eg, beta-sitosterol, stigmasterol), antioxidant tocopherols, antihelminthic cucurbitin, squalene, and cardioprotective fatty acids have been isolated from the seeds and seed oil. The presence of squash inhibitors (serine protease inhibitors) is thought to confer a protective effect to the plant against pests and pathogens.(Akwaowo 2000, Caili 2006, Chiche 2004, Krauze-Baranowska 1996, Naghii 2007, Ryan 2007, Stevenson 2007, Wong 1985)
Uses and Pharmacology
Animal and preclinical data
In vitro experiments and animal studies evaluating dried seeds and extracts of pumpkin and plants of the Cucurbitaceae family have demonstrated anthelmintic action against some Schistosoma japonicum and malarial parasites, but not all parasites (eg, tapeworm).(Amorim 1991, DeAmorim 1992, Elisha 1987)
A preclinical study demonstrated an anthelmintic effect with pumpkin seed 23 g in 100 mL of water(Caili 2006); however, other more effective single-dose vermifuges are preferred.
Benign prostatic hyperplasia
Pumpkin seed extract may have antiandrogenic and anti-inflammatory activities.(Dreikorn 2002)
A protective effect on testosterone-induced prostatic hyperplasia was observed in a study of rats fed pumpkin seed oil.(Gossell-Williams 2006)
Trials are limited, with conflicting results. A large clinical trial evaluating effects of pumpkin seed in 476 men found an improvement in symptoms associated with BPH, as determined by International Prostate Symptom Score (IPSS), but no change in objective measures (eg, prostate volume, postvoid residual urine).(Dreikorn 2002) In another clinical trial, a preparation of C. pepo (Curbicin) improved certain parameters of BPH, including urinary flow, micturition time, residual urine, and urinary frequency, versus placebo.(Carbin 1990)
In a study of men with BPH-related lower urinary tract infections (UTIs) (N=1,431) randomized to 12-month treatment with pumpkin seed 5 g twice daily, pumpkin seed extract 500 mg twice daily, or placebo, IPSS did not differ significantly between pumpkin seed extract and placebo; the difference between pumpkin seed and placebo was significant but descriptive only, as the confirmatory statistical testing strategy was stopped after the nonsignificant result for comparison between pumpkin seed extract and placebo. All individual symptoms improved in all groups; no clinically important changes in prostate volume, postvoid residual volume, or prostate-specific antigen levels were observed.(Vahlensieck 2015)
In the context of a narrative review, C. pepo seems to show efficacy in improving BPH-associated urinary symptoms (eg, gradual improvement in maximal urinary flow rate, reduction in IPSS), with mild adverse effects; however, further clinical trials are needed to confirm findings. The clinical studies analyzed in the review are based on evidence arising from experimental studies in the preclinical setting.(Damiano 2016)
In a single-arm, monocenter pilot study of 60 men with symptoms of BPH (IPSS of 14.8), the effects of a proprietary oil-free hydroethanolic pumpkin seed extract were investigated. Subjects ingested oil-free hydroethanolic pumpkin seed extract once daily (before going to bed) for 3 months. After 12 weeks of supplementation, a significant symptom reduction from baseline (average, 30.1%) was observed based on total IPSS. Symptom alleviation also had a high impact on quality of life (P<0.0001) and was significant after 8 and 12 weeks of intervention (P<0.001). Nocturia significantly decreased over time (P<0.0001), as confirmed by IPSS questionnaire and bladder diary. Postvoid residual urine volume was significantly reduced at the end of intervention (from 83.67 mL [95% CI, 58.02 to 109.3] at baseline to 63.11 mL [95% CI, 45.37 to 80.85] after 12 weeks; P=0.0394). Results indicate that the oil-free hydroethanolic pumpkin seed extract was well tolerated and provided some health benefits in BPH-related symptoms.(Leibbrand 2019)
A summary of the effect of C. pepo on IPSS and flowmetric indices from various trials is included in a review regarding nutraceutical treatment and prevention of BPH and prostate cancer.(Cicero 2019)
The European Association of Urology's 2022 updated guideline on management of non-neurogenic male lower urinary tract symptoms (LUTS), including benign prostatic obstruction, makes no specific recommendation, but references the European Union herbal monograph for the traditional use of C. pepo, semen (pumpkin seeds) for LUTS related to BPH or an overactive bladder after serious conditions have been excluded. This use is based on sufficient safety data and plausible efficacy from long-standing use and experience.(Gravas 2022)
Limited in vitro and animal experiments have demonstrated antimutagenic and inhibitory actions of pumpkin seed extract and boiled, but not fresh, pumpkin juice.(Caili 2006, Jayaprakasam 2003, Rojas 1980)
In rats, pumpkin seed oil improved the plasma lipid profile (Caili 2006, Gossell-Williams 2008) and exhibited antioxidant activity in the heart and liver.(Zuhair 2000) In these experiments, a hypotensive action was demonstrated with the oil alone, and with the oil in combination with captopril and felodipine.(Gossell-Williams 2008, Zuhair 2000)
Defatted squash seed is rich in tryptophan; limited clinical trials have been conducted comparing plant-based tryptophan with the pharmaceutical grade chemical. In studies evaluating effects of squash-derived tryptophan administered with glucose on CNS blood levels, modest improvements were demonstrated in social anxiety disorder (social phobia) and insomnia.(Hudson 2005, Hudson 2007)
The pulp and seeds of C. ficifolia have been evaluated for hypoglycemic effects on alloxan-induced diabetes in rabbits.(Caili 2006, Roman-Ramos 1995)
Multiple open-label clinical studies report reduced postprandial serum and fasting glucose levels in patients with type 2 diabetes given pumpkin juice or pumpkin powder, but quality clinical trials are lacking.(Caili 2006) A small clinical trial (N=10) demonstrated decreases in fasting blood glucose levels 3 to 5 hours after consumption of the juice of fresh immature C. ficifolia fruit; 4 mL/kg of body weight of the juice was administered (100 g of crushed fruit equivalent to 75 mL of juice).(Acosta-Patiño 2001, Andrade-Cetto 2005) A cross-sectional and follow-up dietary intervention study in hemodialysis patients (n=30) documented significantly improved blood pressure, total cholesterol, triglyceride/high-density lipoprotein cholesterol ratio, serum triglycerides, glucose tolerance, serum fatty acid composition, and inflammatory markers (ie, interleukin 6, tumor necrosis factor alpha, high-sensitivity C-reactive protein) after 12 weeks of dietary supplementation with 30 g/day of a milled flax-sesame-pumpkin seed (3:1:1) mixture added to 200 mL of fat-free milk before dinner. Pruritus also improved in all patients.(Ristic-Medic 2014)
In a study of healthy nonpregnant women (20 to 37 years of age), 30 g of pumpkin seed kernels (providing 4 mg/day of iron) added to 30 g of iron-fortified cereal (providing 7.1 mg/day of iron) for 4 weeks improved iron status. Further studies to determine effects of pumpkin as a food source of iron are needed.(Naghii 2007)
Renal protective effects
In a study of rats treated with cisplatin, pumpkin seeds were found to be nephroprotective, with roasted seeds having a greater effect than raw.(Oyetayo 2020)
Limited high-quality clinical trials exist to support therapeutic dosing. C. ficifolia fruit juice 4 mL/kg of body weight (100 g of fruit equal to 75 mL of juice) was administered twice (at least 1 week apart) in a study conducted among patients with type 2 diabetes.(Acosta-Patiño 2001, Andrade-Cetto 2005) Pumpkin seed 30 g/day provides approximately 4 mg/day of iron and was administered in a clinical study of nonpregnant adults for 4 weeks to improve iron status.(Naghii 2007)
Pregnancy / Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking. Antinutrients (eg, oxalates, cyanide, tannin) have been identified in pumpkin seeds and leaves, with detrimental effects on growing rats and chickens.(Akwaowo 2000, Caili 2006)
In an experiment conducted in rats, pumpkin seed oil potentiated the hypotensive effect of captopril and felodipine.(Zuhair 2000)
Clinical trials report few adverse reactions.(Caili 2006, Carbin 1990) In one study, patients with BPH treated with capsules containing 500 mg of pumpkin seed extract did not experience adverse effects.(Dhariwala 2019)
Methemoglobinemia has been reported in infants 2 months or younger who were given zucchini soup for constipation. The adverse reaction was attributed to the high nitrate content of the vegetable.(Savino 2006) Hemolytic crisis was reported in an 8-month-old infant with undiagnosed glucose-6-phosphate dehydrogenase (G6PD) deficiency after eating pumpkin for the first time. DNA analysis of the pumpkin sample revealed it was cross-contaminated with fava bean DNA; the hemolytic reaction was attributed to substances present in fava beans that are known to trigger hemolytic crisis, especially in children with G6PD deficiency. This case underlines the importance of considering cross-contamination between foods grown in the same fields.(Zuccotti 2014)
Vitamin A toxicity with abnormal liver function tests has been reported with prolonged and excessive pumpkin consumption.(Nagai 1999)
IgE-related allergy to zucchini has been reported. Oral allergy syndrome, nausea, diarrhea, and pruritus have also been described in a number of patients. Cross-reactivity to watermelon, cucumber, and other Cucurbitaceae fruits has occurred.(Figueredo 2000, Potter 1994, Reindl 2000)
A number of pathogenic fungi causing deterioration of carved pumpkins have been identified. These fungi could cause severe infection in immunocompromised individuals.(Nagano 2006)
Severe toxicity has not been reported with the use of Cucurbita extracts. Ingestion of C. maxima seeds by rats and pigs during a 4-week period resulted in no changes in most laboratory parameters.(de Queiroz-Neto 1994) In mice, the median lethal dose of freeze-dried C. ficifolia juice was 650 mg/kg.(Andrade-Cetto 2005)
Antinutrients (eg, oxalates, cyanide, tannin) have been found in pumpkin seeds and leaves, having detrimental effects on growing rats and chickens.(Akwaowo 2000, Caili 2006) Trypsin inhibitors have been described in flowers of pumpkin varieties but are not considered antinutritional.(Sotelo 2007)
- Cucurbita digitata
- Cucurbita ficifolia
- Cucurbita maxima
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