Pumpkin

October 2009

Cucurbita pepo L. Family: Cucurbitaceae.

Chilacayote , acorn squash , butternut squash , field pumpkin , fig-leaf gourd , pepo , pumpkin , squash , yellow summer squash , zucchini

Uses

Pumpkin seeds, seed oil, and pumpkin pulp have been evaluated in limited clinical trials for medicinal actions, including anthelmintic, hypotensive, and hypoglycemic activity. The extracts may also be useful for managing symptoms of benign prostatic hyperplasia and anxiety-related disorders, although limited clinical trial information is available.

Dosing

Limited high-quality clinical trials exist to support therapeutic dosing. Pumpkin seed 30 g daily has been used as a source of supplemental iron in nonpregnant adults.

Contraindications

Contraindications have not been identified.

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.

Interactions

An increased anticoagulant effect of warfarin has been reported during concurrent ingestion of a combination preparation of cucurbita, saw palmetto, and vitamin E. Causality of cucurbita was not proven.

Adverse Reactions

Clinical trials report few adverse reactions. Methemoglobinemia caused by high nitrate content has been reported in infants given zucchini soup for constipation. IgE-related allergy to zucchini has been reported, as well as oral allergy syndrome, nausea, diarrhea, and pruritus. Cross-reactivity to watermelon, cucumber, and pumpkin was demonstrated.

Toxicology

There have been no reports of severe toxicity with the use of cucurbita extracts. Antinutrients have been described in the seeds and leaves, including oxalates, tannins, and cyanide.

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. 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. ^1, , ^2, , ³ 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. They have been used to immobilize and aid in the expulsion of intestinal worms and parasites. In some cultures, small amounts of the seeds are eaten on a daily basis as a prophylactic against worm infections. The seeds also have been used in the treatment of prostate disorders. Pumpkin flowers are sometimes added to tacos or soup as a source of protein. ^2, , ^3, , ⁴

The fleshy pulp of Cucurbita is primarily consumed as a vegetable. 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. ^3, , ^5, , ^6, , ^7, , ^8, , ^9, , ^10, , ¹¹

The pumpkin flower is a source of protein. Glutamic and aspartic acid, leucine, valine, phenylalanine, and tryptophan are among the amino acids identified. Phytosterols, such as spinasterol, have been identified, as well as trypsin-inhibitors. ^4, , ^12, , ¹³

Lipids comprise up to 50% of the seed and around 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. ^3, , ^14, , ^15, , ^16, , ^17, , ^18, , ^19, , ²⁰

Anthelmintic activity

Animal data In vitro experiments and animal studies have demonstrated anthelmintic action of dried seeds and extracts against some Schistosoma japonicum and malarial parasites, but not all parasites (eg, tapeworm). ^21, , ^22, , ²³

Clinical data A preclinical study demonstrated an anthelmintic effect with pumpkin seed 23 g in 100 mL water; however, cucurbitin has been generally supplanted by more effective single-dose vermifuges. ³

Benign prostatic hyperplasia (BPH) Pumpkin seed extract may have antiandrogenic and anti-inflammatory activity. ²⁴

Animal data A protective effect on testosterone-induced prostatic hyperplasia was seen in rats fed pumpkin seed oil. ²⁵

Clinical data Trials are limited and the results conflict. A large clinical trial (N = 476) found an improvement in symptoms associated with BPH as determined by the International Prostate Symptom Score, but no change in objective measures, such as p-vol or post-void residual urine. ²⁴ Another clinical trial found that a preparation of C. pepo (curbicin) improved certain parameters of BPH, including urinary flow, micturition time, residual urine, and urinary frequency versus placebo. ²⁶

Cancer Limited in vitro and animal experiments have shown antimutagenic and inhibitory actions of pumpkin seed extract and boiled, but not fresh, pumpkin juice. ^3, , ^27, , ²⁸

Cardiovascular effects In rats, pumpkin seed oil improved the plasma lipid profile ^3, , ^29, and exhibited antioxidant activity in the heart and liver. ^30, In these experiments, a hypotensive action was demonstrated by the oil alone, and in combination with captopril and felodipine. ^29, , ³⁰

CNS Defatted squash seed is rich in tryptophan. ^31, , ^32, Limited clinical trials have been conducted comparing plant-based tryptophan with the pharmaceutical grade chemical. Modest improvements were demonstrated in social anxiety disorder (social phobia) and insomnia when squash-derived tryptophan was administered with glucose to improve CNS blood levels. ^31, , ³²

Diabetes

Animal data The pulp and seeds of C. ficifolia have been evaluated for hypoglycemic action in alloxan-induced diabetic rabbits. ^3, , ³³

Clinical data 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. ³ 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 crushed fruit was equivalent to 75 mL of juice). ³⁴

Limited high-quality clinical trials exist to support therapeutic dosing. Fresh pumpkin juice 4 mL/kg of body weight was administered in a study conducted among patients with type 2 diabetes. ^34, However, it would take 100 g of crushed fruit to equal 75 mL of juice. ^35, Pumpkin seed 30 g provide approximately 4 mg of iron. When administered to nonpregnant adults for 4 weeks, iron status improved. ^14, Pumpkin seed 23 g per 100 mL was used in a study of anthelmintic action. ³

Information regarding safety and efficacy in pregnancy and lactation is lacking. Anti-nutrients (eg, oxalates, cyanide, tannin) have been identified in pumpkin seeds and leaves, with detrimental effects on growing rats and chickens. ^3, , ¹⁹

In an experiment conducted in rats, pumpkin seed oil potentiated the hypotensive effect of captopril and felodipine. ³⁰ Two men stabilized on warfarin experienced an increase in the international normalized ratio (INR) after taking an herbal combination containing Cucurbita , saw palmetto, and vitamin E. ³⁶ In both patients, the INR returned to previous values when the herbal product was discontinued. Although neither Cucurbita nor saw palmetto can be ruled out as the cause of the INR increase, it is more likely that vitamin E interfered with vitamin K-dependent clotting factors, adding to the anticoagulant effects of warfarin. ³⁶

Clinical trials report few adverse reactions. ^3, , ²⁶

Methemoglobinemia has been reported in infants 2 months of age or younger who were given zucchini soup for constipation. The adverse reaction was attributed to the high nitrate content of the vegetable. ³⁷

Vitamin A toxicity, with abnormal liver function tests, has been reported with prolonged and excessive pumpkin consumption. ³⁸

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 pumpkin has occurred. ^39, , ^40, , ⁴¹

A number of pathogenic fungi causing the deterioration of carved pumpkins have been identified. These fungi could cause severe infection in immunocompromised individuals. ⁴²

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. ⁴³ The median lethal dose of freeze-dried C. ficifolia juice in mice was 650 mg/kg. ³⁵

Antinutrients (eg, oxalates, cyanide, tannin) have been found in pumpkin seeds and leaves, having detrimental effects on rats and chickens. ^3, , ^19, Trypsin inhibitors have been described in flowers of pumpkin varieties, but were not considered antinutritional. ⁴

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