Editor’s Note: Each month, HerbalEGram highlights a conventional
food and briefly explores its history, traditional uses, nutritional profile,
and modern medicinal research. We also feature a nutritious recipe for an
easy-to-prepare dish with each article to encourage readers to experience the
extensive benefits of these whole foods. With this series, we hope our readers
will gain a new appreciation for the foods they see at the supermarket and
frequently include in their diets.
The basic materials for
this series were compiled by dietetic interns from Texas State University in
San Marcos and the University of Texas at Austin through the American Botanical
Council’s (ABC’s) Dietetic Internship Program, led by ABC Education Coordinator
Jenny Perez.
We would like to acknowledge Perez, ABC Special Projects Director Gayle Engels,
and ABC Chief Science Officer Stefan Gafner, PhD, for their contributions to
this project.
By Hannah Baumana and Laura Bakerba HerbalGram Assistant Editor b ABC Dietetics Intern (TSU, 2014)
History and Traditional Use
Range and Habitat
Cucurbita
pepo is a species in the gourd family which
includes many varieties of winter squash and summer squash. Any round and
orange fruit yielded by any variety or cultivar (there are many cultivars) of
the species is usually called a pumpkin, even though the word has no real
botanical meaning.1,2 The species
is characterized by sprawling, coarse vines and climbing tendrils that are
flexible, hollow, and prickly to the touch with large, oval-shaped leaves.3
Cucurbita pepo flowers are bright
yellow or orange with rounded lobes that angle outwards.
The species can produce a wide variety of fruits of different shapes, sizes,
and colors, but pumpkins are spherical in shape, covered by a firm, ribbed,
thick layer of orange or yellow skin. Inside the skin, the fleshy part of the
pumpkin is mildly sweet and grainy. Each fruit contains a large quantity of
seeds, which are flat and ovate-elliptical shaped, dark green in color and
enclosed in a creamy white husk. The seed has a fibrous texture with a subtle
sweetness and nuttiness. Pumpkins range in size from less than a pound to over
1,000 pounds, but average 7-10 pounds.4 Cucurbita pepo is native to Central America, and evidence of
cultivation and use dates back to 5500 BCE.5 The United States is
the top producer of pumpkins, followed by Mexico, India, and China, respectively.6 Phytochemicals and Constituents
Several bioactive constituents in pumpkin exhibit medicinal properties, such as
anti-diabetic, anti-fungal, anti-bacterial, anti-inflammatory, hypotensive, and
antioxidant actions.3,7 The pumpkin
fruit is low in fat and has protein-rich seeds, which make it a nutrient-dense
food. Specific peptides and proteins found in pumpkin
seeds have demonstrated broad-spectrum antimicrobial activity.7 For
example, two of these proteins, alpha-moschin and beta-moschin, have exhibited
inhibitory activity against fungal infections caused by Botrytis cinerea, Fusarium
oxysporum, and Mycosphaerella
arachidicola. Additionally, pumpkin proteins display a synergistic effect
with antibiotics for the inhibition of the fungus Candida albicans, which can cause mucous membrane infections, such
as thrush, in humans.
Some of the bioactive compounds in pumpkin fruit flesh that offer beneficial
health effects are polysaccharides, para-aminobenzoic acid, oils, phytosterols
(beta-sitosterol, sitostanol and avenasterol), proteins, peptides, and lignans.3
Anti-diabetic effects are due to protein-bound polysaccharides (PBPP), which
have been shown to increase levels of insulin, decrease blood glucose levels,
and enhance glucose tolerance.7 Researchers theorize that this
happens due to antioxidant activities which are thought to prevent destruction
of pancreatic beta-cells, which produce insulin.6 Therefore, PBPP
present in pumpkin may play a role in preventing the development and
progression of diabetes.7,8
Additionally, the polyamine content of pumpkins may also play a role in
optimizing the function of the pancreas.7 Pumpkin seeds are rich in
phytoestrogen content (265 mg per 100g), specifically secoisolariciresinol.9
Secoisolariciresinol has been shown to exhibit cholesterol-lowering activity,
and produce cardioprotective effects through the formation of new blood vessels
and decreased apoptosis (programmed cell death). These effects are thought to
be the result of antioxidant properties, which inhibit cell membrane damage and
scavenge “free radicals.” Pumpkin seeds also contain beneficial compounds such
as linoleic acid, essential amino acids, and vital micronutrients. Linoleic and linolenic acids exhibit oxidative mechanisms to reduce the
production of inflammatory products, while oleic fatty acid is known to enhance
signaling pathways of vasodilation (expanding blood vessels), promote a
reduction in blood pressure levels, and reduce effects of vasoconstriction
(narrower diameter of blood vessels). Pumpkin seeds are also a good source of
trace minerals including magnesium, zinc, copper, and selenium.3
The bright orange color of pumpkin indicates elevated levels of beta-carotene,
a vital antioxidant and precursor to vitamin A, which maintains vision and the
health and function of bones, skin, and mucous membranes.4,10
Additionally, the fruit contains gamma-aminobutyric acid (GABA; a neurotransmitter that has
inhibitory effects on the nervous system) and modest
levels of carbohydrates, vitamins, and minerals.3
Historical and Commercial Uses
The name “pumpkin” originates from the Greek word pepon, which means “large melon.”4 The French modified
this name to pompon and the British
changed it to pumpion, which was
later changed by the American colonists to pumpkin.6
Pumpkin has a traditional history as a food and medicine. Some Native American
tribes dried the skins of pumpkins into strips and wove them together into
mats.4 The modern pumpkin pie has its origins in colonial New
England, where colonists cut off the top of the pumpkin, removed the seeds,
filled the fruit with milk, spices, and honey, and baked the fruit over hot
ashes.4,5 Pumpkins are highly
valued in Chiapas, Mexico, where they are combined with honey for the
preparation of the dessert palanquetas.3
Though native to Central America, the
pumpkin was one of the first foods from the “New World” to be brought back to
Europe, and cultivation spread quickly thereafter.5 Pumpkins have
been used as a medicine in several countries. For example, the former Yugoslav
Republic of Macedonia, Argentina, India, Brazil, and Mexico have traditionally
used pumpkins as a treatment for diabetes.11 In addition,7 pumpkin
seed oil from a particular variety known as the Styrian pumpkin (C. pepo subsp. pepo var. styriaca)
produced in southern Austria and Slovenia is a European Union Protected
Designation of Origin product. Nicknamed “green gold,” the dark green oil has
culinary and medicinal applications and is an integral part of the local
culture throughout Eastern Europe.12 The seeds of pumpkins have also been
used as a vermifuge for intestinal parasites and worms.
In addition to the many health benefits
offered by pumpkin, it also is used as an ornamental decoration during the US
holidays Halloween and Thanksgiving and has recently become a crop of interest
in agritourism (defined broadly, agritourism is the act of visiting any
agricultural operation or business in order to be educated or entertained).13
Currently, pumpkin farms in California are considered to be one of the most
popular and lucrative agritourism attractions, commonly offered in conjunction
with pony rides and corn mazes.
Modern Research
Current research on the medicinal possibilities of C. pepo focuses heavily on pumpkin seeds and pumpkin seed oil
(PSO). Studies show that pumpkin seeds have therapeutic potential for a variety
of conditions, including benign prostatic hyperplasia (BPH), urinary tract
infections associated with BPH, hypertension, diabetes, and microbial
infections.
Researchers theorize that the phytosterol content of pumpkin seeds can prevent
testosterone-induced BPH by inhibiting the conversion of testosterone to
dihydrotestosterone.14 Male
rats with testosterone-induced BPH given a daily dose of pumpkin seed oil were
found to have reduced levels of hyperplasia. This further indicates that PSO
may be directly involved in prostate health.
Pumpkin seeds have been shown to be an effective alternative treatment for
lower urinary tract symptoms (LUTS) secondary to BPH.13 BPH is
characterized by an enlargement of the prostate gland, which commonly results
in the constriction of the lower urinary tract in men.15,16 Fifty
percent of men over the age of 60 report having BPH, with 15%-30% of these men
also having LUTS.16 A 12-month study of men diagnosed with BPH/LUTS
was conducted to analyze the health effects of pumpkin seeds.16
Doses of purified pumpkin seed, pumpkin seed extract, or placebo were
administered twice daily. Both treatment modalities exhibited statistically
significant improvements as measured by the International Prostate Symptom
Score screening tool (I-PSS) and quality of life (QoL) scores. Additionally,
the pumpkin seed group revealed greater improvements in IPSS-related QoL scores
than the placebo group. QoL scores were enhanced 36% for pumpkin seed,
33.4% for pumpkin seed extract, and 29.2% for the placebo
treatment group.
Another 12-month study revealed similar results, with I-PSS scores
significantly enhanced after administration of 320 mg of PSO twice daily.17
This study also showed a decrease in prostate volume and a significant increase
in maximal urinary flow rate. The intervention resulted in an average increase
from 14 mL/second at baseline to 17 mL/second after taking PSO for an
improvement of 14.9% in urinary flow rate.
Pumpkin seed oil enhances cardiovascular health through its antihypertensive
and atheroprotective characteristics.6 Hypertensive rats fed either
40 mg/kg/day or 50 mg/kg/day of PSO for six weeks exhibited cardioprotective
effects.18 The study showed that use of PSO resulted in a
significant reduction of high systolic blood pressure and proved to be as
effective as a common antihypertensive medication (amlodipine) in reducing high
blood pressure by producing close to normal levels of nitric oxide.6,18
This mechanism may be a result of the linoleic, linolenic fatty acid and/or
oleic fatty acid content of pumpkin seeds.18 PSO also exhibited
antioxidant effects by increasing low levels of nitric oxide metabolites back
to normal and significantly reduced indicators of oxidative stress known as
malondialdehydes (MDAs).
A study of post-menopausal women found that consumption of pumpkin seeds
increased levels of high-density lipoprotein (HDL) cholesterol by 16% and
decreased diastolic blood pressure by 7%.6,9 These effects may be
attributed to the high content of the phytoestrogen secoisolariciresinol, which has been shown to exhibit
cardioprotective properties through its antioxidant content.9 Subjects also experienced a decrease in severity of hot flashes,
decreased occurrence of headaches, and reduced joint pain. These findings
provide supporting evidence of PSO supplementation for improved cardiovascular
health.
Pumpkin seeds
traditionally have been used for their anti-diabetic properties and are a
promising area of research in diabetes treatment. Due to the hypoglycemic
activities observed in animal and human studies, PSO may eventually be
considered as an alternative modality of treatment. Hypoglycemic effects are
due to bioactive constituents such as polysaccharides, para-aminobenzoic acid,
oils, sterols, proteins, peptides, and macromolecules such as trigonelline,
nicotinic acid, and D-chiro-inositol. D-chiro-inositol is
classified as an insulin sensitizer and plays a vital role in the anti-diabetic
properties of pumpkin.3 A study done on
diabetic rats with orally administered polysaccharides isolated from pumpkin
fruits revealed improvements in insulin regulation and glucose levels.7
These animal studies offer intriguing evidence of pumpkin’s anti-diabetic
properties, though additional research and human clinical trials are needed to
support the implementation of pumpkin as a medicinal alternative for glycemic
control.11
Pumpkin seed oil has exhibited broad spectrum antimicrobial effects in cell
culture studies with the following organisms: Acinetobacter
baumannii, Aeromonas veronii biogroup sobria, Candida albicans, Enterococcus
faecalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serotype typhimurium, Serratia
marcescens, and Staphylococcus
aureus.3,7 These findings hold a twofold benefit for developed
and developing countries: as antibiotic-resistant bacteria grow more prevalent,
scientists are working to identify plant-based compounds with antimicrobial
actions; additionally, pumpkin consumption in countries with insufficient
health care infrastructures may serve as a protection against harmful organisms
that result in infectious diseases.3 Pumpkin and PSO should be
further researched to validate these possible uses.
Nutrient Profile19
Macronutrient Profile: (Per 1 cup raw 1” cubes [approx. 116 g])
30 calories 1.16 g protein 7.54 g carbohydrates 0.10 g fat
Secondary
Metabolites: (Per
1 cup raw 1” cubes [approx. 116 g])
Excellent source
of: Vitamin A: 9,875 IU (197.5% DV)
Very good source
of: Vitamin C: 10.4 mg (17.3% DV) Potassium: 394 mg (11.26% DV)
Good source of: Iron: 0.93 mg (5.2% DV) Phosphorus: 51 mg (5.1% DV)
Also provides: Folate: 19 mcg (4.75% DV) Vitamin E: 1.23 mg (4.6% DV) Thiamin: 0.06 mg (4% DV) Magnesium: 14 mg (3.5% DV) Niacin: 0.7 mg (3.5% DV) Vitamin B6: 0.07 mg (3.5% DV) Calcium: 24 mg (2.4% DV) Dietary Fiber: 0.6 g (2.4% DV) Vitamin K: 1.3 mcg (1.6% DV)
DV = Daily Value as established by the US
Food and Drug Administration, based on a 2,000-calorie diet.
Recipe: Pumpkin-Shiitake Risotto
Ingredients:
- 4-5
cups vegetable stock
- 2
tablespoons olive oil
- 1
medium yellow onion, finely chopped
- 2
cups shiitake mushroom caps, sliced
- 2
garlic cloves, minced
- 1
cup uncooked Arborio or other short-grain rice
- ½
cup dry white wine
- ½
teaspoon kosher salt
- 1
cup fresh or canned unflavored pumpkin puree
- 2
tablespoons fresh chives, chopped
Directions:
- In a medium
saucepan, heat the broth until simmering. Reduce heat to low and keep warm.
- In a large nonstick
pan, heat the oil over medium heat until shimmering. Add the onions, mushrooms,
and garlic and cook, stirring occasionally, until softened, about 6-7 minutes.
- Add the rice to the
pan and cook, stirring constantly, until the rice is lightly toasted and coated
in oil, about 1 minute. Add the wine and reduce until nearly evaporated.
- Ladle 1 cup of the
warm broth into the rice and stir constantly until the rice absorbs most of the
liquid. Reduce heat, if necessary, to maintain a simmer.
- Continue adding the
broth in 1-cup increments, each time waiting for the rice to absorb most of the
liquid, approximately 20-30 minutes. The rice will slowly become creamy and
cooked, with tender grains and a loose sauce.
- Reduce heat to low.
Stir in the salt and pumpkin puree and heat through. Garnish with chives and
serve immediately.
References
- What
is the difference between pumpkins, squashes and gourds? Missouri Botanical
Garden website. Available here. Accessed October
15, 2015.
- Cucurbita
pepo. Missouri Botanical Garden website. Available here. Accessed October
15, 2015.
- Yadav M, Jain S, Tomar R, Prasad GB, Yadav H.
Medicinal and biological potential of pumpkin: An updated review. Nutr Res
Rev. 2010;23(2):184-190.
- Pumpkins and More. University of Illinois Extension
website. Available here. Accessed September 16, 2015.
- Barksdale
N. The History of Pumpkin Pie. History website. November 21, 2014. Available here. Accessed
September 16, 2015.
- Gamonski W. The true potency of the pumpkin seed. Life
Extension. 2012;18(10):95-98.
- Caili F, Huan S, Quanhong L. A review on
pharmacological activities and utilization technologies of pumpkin. Plant
Foods Hum Nutr. 2006;61(2):70-77.
- Quanhong L, Caili F, Yukui R, Guanghui H, Tongyi C.
Effects of protein-bound polysaccharide isolated from pumpkin on insulin in
diabetic rats. Plant Foods Hum Nutr. 2005;60(1):13-16.
- Gossell-Williams M, Hyde C, Hunter T, et al.
Improvement in HDL cholesterol in postmenopausal women supplemented with
pumpkin seed oil: Pilot study. Climacteric. 2011;14(5):558-564.
- Weil
A, Becker B. Supplements and Herbs: Facts about Vitamin A. Andrew Weil, MD
website. October 29, 2012. Available here. Accessed
September 23, 2015.
- Adams GG, Imran S, Wang S, et al. The hypoglycemic
effect of pumpkin seeds, trigonelline (TRG), nicotinic acid (NA), and
D-chiro-inositol (DCI) in controlling glycemic levels in diabetes mellitus. Crit
Rev Food Sci Nutr. 2014;54(10):1322-1329.
- Košťálová Z,
Hromádková Z, Ebringerová A. Chemical evaluation of seeded fruit biomass of oil
pumpkin (Cucurbita pepo L. var. Styriaca). Chemical Papers. 2009;63(4):406–413.
- Aegerter B, Smith R, Natwick E, Gaskell M, Rilla E.
Pumpkin Production in California. Richmond, CA: University of California
Vegetable Research and Information Center; 2013. Available here. Accessed September 16, 2015.
- Gossell-Williams
M, Davis A, O'Connor N. Inhibition of testosterone-induced hyperplasia of the
prostate of sprague-dawley rats by pumpkin seed oil. J Med Food. 2006;9(2):284-286.
- Vahlensieck
W, Theurer C, Pfitzer E, et al. Effects of pumpkin seed in men with lower
urinary tract symptoms due to benign prostatic hyperplasia in the one-year,
randomized, placebo-controlled GRANU study. Urol
Int. 2015;94(3):286-295.
- Coulson
S, Rao A, Beck SL, et al. A phase II randomised double-blind placebo-controlled
clinical trial investigating the efficacy and safety of ProstateEZE Max: A
herbal medicine preparation for the management of symptoms of benign prostatic
hypertrophy. Complement Ther Med.
2013;21(3):172-179.
- Hong
H, Kim CS, Maeng S. Effects of pumpkin seed oil and saw palmetto oil in Korean
men with symptomatic benign prostatic hyperplasia. Nutr Res Prac. 2009;3(4):323-327.
- El-Mosallamy
A, Sleem AA, Abdel-Salam OM, Shaffie N, Kenawy SA. Antihypertensive and
cardioprotective effects of pumpkin seed oil. J Med Food. 2012;15(2):180-189.
-
Basic Report: 11422,
Pumpkin, raw. Agricultural Research Service, United States Department of
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