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. We would like to
acknowledge ABC Chief Science Officer Stefan Gafner, PhD, for his contributions
to this project.
By Jenny
Pereza and Hannah Baumanb
a ABC Education
Coordinator
b HerbalGram Associate Editor
Overview
The genus
Pyrus consists of 30 deciduous species
and is closely related to the genus Malus,
which includes apples (Malus spp.). Both
genera are part of the economically important Rosaceae family.1,2 Similar
to apples, Pyrus fruits are
classified as pomes, where the seeds are contained in a central,
compartmentalized core.3 The Pyrus
genus is native to Europe, Asia, the Middle East, and North Africa.1 Capable
of living more than 250 years, the pear tree is one of the longest-living fruit
trees.1 Cultivated pears are derived from one or two wild pear
species widely distributed in Europe and western Asia.2 Of the 5,000
varieties cultivated worldwide, the two species grown commercially are the
European pear (P. communis) with its
juicy, aromatic, bell-shaped fruit, and the Asian pear (P. pyrifolia) with its crisp and crunchy, apple-like shape and
texture.1,2,
The European pear is a medium-sized tree that grows to 30-50
feet with a narrow canopy and alternate, glossy green leaves that are oval or
lanceolate in shape.1,2 The Asian pear grows to 30 feet and has green,
oblong, alternately attached leaves that appear orange and bronze in autumn.
Both species have small, white, five-petaled flowers with numerous stamens that
emerge just prior to the leaves in spring.1,2
Historical and Commercial Uses
Both
the Asian pear and the European pear were domesticated in their respective
countries of origin approximately 3,000 years ago. Asian pears were originally
grown in China, Japan, and Korea, while the European pear was domesticated in France,
Germany, and Belgium.3 In 1620, the first pear tree in America was
planted by colonists.4 In addition to its edible fruit, the pear
tree is valued for its ornamental beauty as well as its wood, which is used to
manufacture furniture and woodwind instruments.2
For
thousands of years, pear fruits have been used as medicine in both traditional
Chinese medicine (TCM) and Ayurvedic practices. In both Ayurveda and TCM, Asian
pears are considered sweet and cooling and are used to manage respiratory
diseases such as asthma, rhinitis, and bronchitis.3,5 Pears also are
considered antitussive and are used to soothe coughs, clear phlegm, and relieve
inflammation.3 In general, pears are used for their
anti-hyperglycemic and diuretic properties, while pear juice (Asian pears
specifically) is used to treat shortness of breath during hot days and as a
prophylactic to prevent hangovers from alcohol consumption.3,5 Pear
peel is utilized in cosmetics for the skin-whitening properties attributed to
its arbutin content. In Ayurveda, pears are used as a natural face and body
scrub to reduce dryness, tone the skin, and treat acne.5
Pears
are commercially produced in at least 81 countries with a global annual yield
of approximately 40 billion pounds of fruit.2 China leads the world
with more than 50% of pear production, followed by Italy and the United States.2,4
Within the United States, Washington, Oregon, and California are the leading
pear producers.2 Like other fruit trees in the rose family, many
European pear trees require 900-1,000 chill hours (i.e., hours of exposure to temperatures
between 32°F and 45°F) in order to break dormancy, bloom, and set fruit.2
The most popular varieties of European pear include Bartlett, d’Anjou, Bosc,
Comice, Seckel, and Winter Nelis. The Bartlett pear accounts for 75% of US pear
production and is the most common pear cultivar in the world.2 Asian
pear cultivars have lower chill requirements and can therefore be cultivated in
warmer climates.2 Unlike European pears, Asian pears are allowed to
fully ripen on the tree before harvest.2
While
commonly considered a dessert fruit, pears were once widely used to make hard
pear cider known as “perry.”1 While perry consumption has seen a
decline since the 1970s, there has been a renewed consumer interest in many
countries in recent years. In European countries like Austria, Germany, and
Switzerland, hard cider made from mixtures of apple and pear juices is still
popular. Pear pomace (the remaining skin, seeds, and core post-processing) has
been studied for its potential as a fiber supplement to fortify low-fiber food
products, such as baked goods.3
Phytochemicals and Constituents
According
to the 2001-2010 National Health and Nutrition Examination Survey (NHANES)
study, pears are the 11th most commonly consumed fruit in the United States.6
Pears contain a high amount of digestion-regulating carbohydrates, specifically
fructose, sorbitol, and both soluble and insoluble fiber.3,4 In
fact, pears have a higher pectin content than apples.4 Pectin acts
like a sponge throughout the digestive system, absorbing water, removing waste
and toxins, and lowering cholesterol.4,7 The consumption of one
medium-sized pear daily could enhance bowel transit time and meet nearly 25% of
the adult daily dietary fiber requirement.3
Pear is
also a good source of potassium and vitamin C.9 Potassium is essential
for healthy muscles, nervous system function, and blood pressure levels. Vitamin
C helps regulate metabolism and enhances wound healing, tissue repair, and
immune function.9 According to the healthy eating index (HEI), individuals
who consume pears were more likely to have higher-quality diets and consume
higher amounts of vitamin C, magnesium, copper, dietary fiber, and potassium
than those who do not consume pears.6
Pears
have a unique sugar profile due to their higher content of fructose compared to
sucrose and glucose. Fructose gives pears their characteristic sweet taste and is
a rich source of sorbitol, a natural fruit sugar alcohol that is poorly
absorbed and associated with a laxative effect when consumed in excess.3
Despite their sweet taste, pears have, on average, a glycemic index (GI) value
of 38, which is comparable to apples and, as it is a GI score under 55, considered
low. Eating foods with a low GI value is important for both weight and blood
sugar management as these foods are digested and absorbed more slowly and have
a minimal impact on blood glucose levels.3
The
phenols abundant in pear fruit and peel include arbutin, flavonoids, and
phenolic acids. The most abundant flavonoids in pears are catechins (flavan-3-ol
monomers and polymers) and cyanidin glycosides. The highest concentration of cyanidin
glycosides (a type of anthocyanin with antioxidant properties) is found in the
peel of red pears.3 The phenolic acids found in pears — chlorogenic
acid, ferulic acid, and citric acid — also contribute to pear’s health benefits.
Both ferulic and chlorogenic acid are being studied for their ability to
inhibit α-glucosidase and α-amylase, which appear to delay the digestion and
absorption of carbohydrates.3 Ferulic acid is a potent antioxidant
with a range of anti-inflammatory, anti-atherogenic, anti-diabetic,
neuroprotective, and hepatoprotective effects. The citric acid content of some
pear cultivars is considered high for non-citrus fruits (more than 2 g/kg fresh
fruit) and has been shown to improve dietary iron absorption by as much as
600%.3
Pear
cultivars with greenish-yellow and red-blush peels typically are high in chlorogenic
acid and arbutin.8 In humans, chlorogenic acid regulates the
metabolism of fats and glucose in the body and therefore plays an important
role in managing diabetes and cardiovascular disease (CVD), while arbutin has
anti-hyperglycemic, anti-hyperlipidemic, and antioxidant properties and is
involved in alcohol metabolism.3
Modern Research
Researchers
have examined various pear parts and preparations including whole pear fruit,
pear peel, pear pulp, pear pomace, or pear extracts.3 Studies
published on pear generally are observational or animal. Most human clinical
studies of pear do not exclusively focus on pear but also include apple
consumption. Although apples and pears are closely related, further
investigation is needed focusing solely on pear.
Metabolic Health Markers and Chronic
Disease
Hypertension,
dyslipidemia, abnormal blood glucose, and chronic inflammation result from metabolic
abnormalities that contribute to the onset of conditions such as cardiovascular
disease (CVD), type 2 diabetes mellitus (T2DM), and cancer.3 Fruit
and vegetable consumption can drastically reduce the risk of CVD. For every 200
g/day intake of fruit and vegetable consumption, stroke risk has been shown to decrease
by as much as 32%.3 Results from three prospective studies indicate
that consumption of both apples and pears is associated with a lower risk of
stroke and CVD. While the effects of pear consumption alone were not assessed in
these studies, it is thought that the fiber and polyphenols in pear work
synergistically to affect blood pressure, lipid profiles, body weight,
inflammation, and oxidative stress.
Weight
management is a critical part of correcting metabolic abnormalities and
improving overall health. Fruits are low-energy-dense foods that induce satiety
without increasing calorie intake.10 Pear fruit is a low-calorie,
high-fiber snack that has been studied for its potential in promoting weight
loss. Regular consumption of pears is associated with lower body weight and a
35% reduction in risk of becoming obese.6 In one randomized clinical
trial, 49 overweight middle-aged women were randomly assigned to add three pears, three apples, or three oat (Avena
sativa, Poaceae) cookies to their regular diet. Participants who consumed pears
or apples experienced significantly more weight loss compared to those who
consumed oat cookies after 10 weeks.10 Since the fiber content of
the oat cookie, pear, and apple was similar, researchers attributed the weight
loss to the low energy density of pears and the overall reduction in daily caloric
intake even though more food was consumed by weight.3,10
T2DM,
which is characterized by hyperglycemia and insulin resistance, is one of the
fastest growing preventable chronic diseases in developed countries worldwide.
There is consistent evidence from observational studies that daily pear and
apple consumption is associated with a reduced incidence of T2DM. A cohort
study by Muraki et al. found an inverse relationship between apple and pear
consumption (collectively) and T2DM. An intake of more than one apple or pear
daily correlated with a 17% reduction in T2DM risk.3 Additionally, participants
who consumed three servings of juice made from whole pears and/or apples weekly
showed a 14% lower risk of developing T2DM.3,11 Similar research has
found the strongest inverse association from intake of anthocyanin-rich foods
(such as unpeeled pears and apples) and the risk of T2DM.3,12 The
peel of the pear fruit contains six to 20 times the antioxidant nutrients than
the flesh. Additionally, studies have shown that removing the peel of the pear decreases
the phenolic and vitamin C content of the fruit by 25%.13 Similar to
other fruits and vegetables, consuming pears, peel and all, provide a complete
array of its nutrients.13
Five
out of the six published prospective and case-controlled studies on pears and
apples have demonstrated that increased consumption of these fruits is
associated with a reduced risk of certain types of cancer. A cohort study of
more than 470,000 women and men across Europe found that both apple and pear
consumption was associated with reductions in bladder cancer (each 25 g
increment consumed resulted in a 7% risk reduction) and lung cancer (each 100 g
increment consumed resulted in a 14% risk reduction).3 In addition,
a study by Rossi et al. showed that for each portion of apple or Asian pear
consumed, pancreatic cancer risk decreased by 27%.3 Pears contain
ursolic acid, which inhibits aromatase activity, and its isoquercitrin helps
maintain DNA integrity; these factors both play a role in cancer development.5
Additional studies are needed to further investigate pear’s potential cancer preventive
properties and mechanisms.
Gastrointestinal Health
Both
sorbitol and fructose are poorly absorbed in the small intestine and attract
and move water into the large intestine, which softens the stool and elicits a
laxative effect.3 Pear’s fructose and sorbitol content combined with
its dietary fiber and pectin content gives the fruit the natural ability to
prevent and treat constipation.3 Using pears to treat constipation
may be especially useful in children who may be unaccustomed to taking
medications or older adults who are often taking several medications.3
However, eating too many pears when not constipated may cause loose stools or
diarrhea, especially in young children.13
Individuals
with irritable bowel syndrome (IBS) often experience malabsorption issues as
well as digestive discomfort upon eating foods high in fructose (e.g., honey,
fruits, and corn [Zea mays, Poaceae] syrup);
fructans such as inulin, which is found in wheat (Triticum aestivum, Poaceae) and onions (Allium cepa, Amaryllidaceae); and polyols such as sorbitol found in
fruit and artificially sweetened foods. Due to their fructose and sorbitol
content, pears should be avoided by those following a low FODMAP (Fermentable Oligosaccharides,
Disaccharides, Monosaccharides, and Polyols) diet.3,5
Hangover Helper
The
key enzymes in alcohol metabolism are alcohol dehydrogenase (ADH) and aldehyde
dehydrogenase (ALDH). Consumption of high volumes of alcohol depletes these enzymes,
which are needed to detoxify the body, and often results in a hangover. Symptoms
of a hangover include headache, fatigue, diarrhea, dizziness, and poor
concentration. Certain Asian populations have a genetic variation known as ALDH2,
which is associated with a reduced, or inefficient, ability to metabolize
alcohol.3 In an acute crossover randomized clinical trial, 14
healthy men consumed 220 mL of Asian pear juice or placebo (juice with fructose
and pear flavoring) prior to consuming 540 mL of 20% alcohol. Participants that
did not have the ALDH2 genetic variant in the pear juice group experienced
significant alleviation of hangover symptoms. However, those who had the
genetic variant did not experience alleviation from hangover symptoms when
consuming pear juice prior to alcohol consumption.14 By adding
fructose to the placebo drink, it was ruled out as a possible active ingredient.
Research has confirmed that arbutin is the primary constituent responsible for
stimulating ADH and ALDH activity and reduces the occurrence or severity of
hangovers.3 Future larger studies including populations from other
ethnicities need to be conducted to confirm these findings and assess the
impact of different ethnic backgrounds.14
Allergic and Respiratory Conditions
Pears
are considered a low allergenic food and are often one of the earliest foods
introduced to infants.3,4 In a cross-sectional study of 244 eight-year-old
children who were sensitive to food-based allergens, there was an inverse
association between pear and apple intake and allergic symptoms, including
rhinitis, asthma, and chronic skin conditions like eczema.3 Pears
are rich in quercetin and rutin, which down-regulate mast cell activity,
reducing the severity of immune response to allergens.3 Clinical
research is necessary before recommendations can be made regarding pear
consumption as a dietary treatment for allergic and respiratory conditions.
Consumer Considerations
Peak
season for pears is late summer to early autumn.3 Root cellars are
used to store and slowly ripen immature European pears after harvest, which allows
a longer period of consumer access to these late-season fruits. Pears are eaten
fresh or cooked, canned, preserved as jams, juiced, dried, or fermented into hard
pear cider.2,3 Of the pears grown in the United States, only 60% are
available to consumers in whole fruit form, while 40% of pears are processed
into prepared foods or canned. When selecting fresh pears, one should choose fruits
that slightly yield to pressure, like an avocado.4,13 Unripe pears
will ripen if stored at room temperature or, temporarily, in a brown paper bag.
Once ripe, pears should be stored in the refrigerator away from strong-smelling
foods, as pears tend to absorb odors.4
Fruits
and vegetables that have thin skins are prone to pesticide residue accumulation.
Pears, with their thin, phytonutrient-rich skins, are listed among the top 12
fruits and vegetables that have the highest pesticide residues, according to
the “2018 Shopper’s Guide to Pesticides in Produce” published by the consumer
advocacy organization known as the Environmental Working Group.15
According to the organization’s 2018 data, 48% of conventionally grown pears were
shown to have an average of five detectable pesticides. Since 2010, the amount
of pesticide residues on pears has more than doubled from 0.6 ppm to 1.4 ppm. Due
to the cumulative nature of fat-soluble pesticide residues within the human body,
it is important to wash produce in a diluted vinegar solution (three parts
water to one part vinegar) to help remove pesticide residues.4 For
infants, the elderly, or those with chronic illnesses, purchasing and consuming
organically grown pears and pear products is strongly recommended.
Nutrient Profile16
Macronutrient Profile: (Per 1 small
European pear [approx. 148 g])
84 calories
0.53
g protein
22.5
g carbohydrate
0.21
g fat
Secondary Metabolites: (Per 1 small
European pear [approx. 148 g])
Very good source of:
Dietary
Fiber: 4.6 g (15.3% DV)
Good source of:
Vitamin
C: 6.4 mg (7% DV)
Vitamin
K: 6.5 mcg (5.4% DV)
Folate:
10 mcg (2.5% DV)
Also provides:
Potassium:
172 mg (3.7% DV)
Riboflavin:
0.04 mg (3.1% DV)
Manganese:
0.07 mg (3% DV)
Magnesium:
10 mg (2.4% DV)
Vitamin
B6: 0.04 mg (2.4% DV)
Thiamin:
0.02 mg (1.7% DV)
Iron:
0.27 mg (1.5% DV)
Niacin:
0.24 mg (1.5% DV)
Phosphorus:
18 mg (1.4% DV)
Vitamin
E: 0.18 mg (1.2% DV)
Calcium:
13 mg (1% DV)
Provides trace amounts:
Vitamin
A: 37 IU (0.7% DV)
DV =
Daily Value as established by the US Food and Drug Administration, based on a
2,000-calorie diet.
Recipe: Arugula
and Pear Salad with Maple Vinaigrette17 Courtesy of Sara
Quessenberry
Ingredients:
- 1 tablespoon
maple syrup
- 1
teaspoon Dijon mustard (To learn more about the benefits of mustard, click here.18)
- 1
tablespoon red wine vinegar
- 1/4
teaspoon kosher salt
- 1/8
teaspoon black pepper
- 2
tablespoons extra-virgin olive oil
- 8
cups arugula leaves (To learn more about the benefits of arugula, click here.19)
- 1
pear, unpeeled, thinly sliced
- 1/2
cup (3 ounces) blue cheese, crumbled
Directions:
- In
a small bowl, whisk together maple syrup, mustard, vinegar, salt, and pepper
until combined. Slowly add oil, whisking constantly, until emulsified. Set
aside.
- Arrange
arugula on individual plates and top with pear slices and crumbled cheese.
Drizzle with dressing to taste and serve.
| Image credits (top to bottom):
European pear tree flowers. Image courtesy of Sten Porse.
Pear illustration by Prof. Dr. Otto Wilhelm Thomé from Flora von Deutschland, Österreich und der Schweiz. 1885.
Asian pear fruit on the tree. Image courtesy of Wikimedia Commons.
European pear fruit. Image courtesy of Rasbak.
Hangover stock image courtesy of Michal Jarmoluk.
References
- National Geographic Society. Edible: An Illustrated Guide to the World’s Food
Plants. Lane Cove, Australia: Global Book Publishing; 2008.
- New
World Encyclopedia. Pear. New World Encyclopedia website. Available at: http://www.newworldencyclopedia.org/entry/Pear.
Accessed on 12-5-18.
- James-Martin
G, Williams G, Stonehouse W, O’Callaghan N, Noakes M. Health and nutritional
properties of pears (Pyrus): a
literature review. Adelaide, Australia: Commonwealth Scientific and Industrial
Research Organization; 2015.
- Murray M. The
Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.
- Parle
M, Arzoo. Why is Pear So Dear? International
Journal of Research in Ayurveda and Pharmacy. Jan.-Feb 2016:7(Suppl
1);108-113.
- O’Neil
C, Nicklas T, Fulgoni V. Fresh pear consumption is associated with better
nutrient intake, diet quality, and weight parameters in adults: National Health
and Nutrition Examination Survey 2001-2010. Journal
of Nutritional Food Science. 2015:5(4).
- Soluble
and Insoluble Fiber. MedlinePlus website. Available at: https://medlineplus.gov/ency/article/002136.htm.
Accessed December 7, 2018.
- Ozturk
A, Demirsoy L, Demirsoy H, et al. Phenolic compounds and chemical characteristics
of pears (Pyrus communis). International Journal of Food Properties,
2015:18;536-546.
- Pear Nutrition.
USA Pear Bureau Northwest website. Available at: https://usapears.org/pear-nutrition/. Accessed December 7, 2018.
- deOliveira
MC, Sichieri R, Mozzer RV. A low-energy-dense diet adding fruit reduces weight
and energy intake in women. Appetite.
2008:291-295.
- Muraki
I, Imamura F, Manson J, et al. Fruit consumption and risk of type 2 diabetes:
results from three prospective longitudinal studies. British Medical Journal. 2013:347;19-28.
- Wedick
N, Pan A, Cassidy A, et al. Dietary flavonoid intakes and risk of type 2
diabetes in US men and women. American
Journal of Clinical Nutrition. 2012:95(4);925-933.
- Reiland
H, Slavin J. Systematic review of pears and health. Nutrition Today. 2015;50(6).
- Lee
HS, Isse T, Kawamoto T, Baik H, Park JY, Yang M. Effect of Korean pear juice on
hangover severity following alcohol consumption. Food and Chemical Tocxicology. 2013:58;101-106.
- The
Dirty Dozen. Shopper’s Guide to Pesticides in Produce. Environmental Working
Group website. Available at: www.ewg.org/foodnews/dirty-dozen.php. Accessed on December 10, 2018.
- Agricultural Research Service. Basic Report: 09252, Pears, raw. National
Nutrient Database for Standard Reference Legacy Release. April 2018. United
States Department of Agriculture website. Available at: https://ndb.nal.usda.gov/ndb/foods/show/09252. Accessed December 12, 2018.
- Quessenberry S. Arugula and Pear Salad with Maple Vinaigrette. Real
Simple website. December 2005. Available at: www.realsimple.com/food-recipes/browse-all-recipes/arugula-pear-salad-maple-vinaigrette. Accessed December 12, 2018.
- Bauman H, Brown Z. Food as Medicine: Mustard (Brassica juncea and B. nigra,
Brassicaceae). HerbalEGram. 2017;14(3). Available at: http://cms.herbalgram.org/heg/volume14/03March/FAMMustard.html.
Accessed December 17, 2018.
- Bauman H, Kwon M. Food as Medicine: Arugula (Eruca sativa, Brassicaceae). HerbalEGram. 2016;13(4). Available at:
http://cms.herbalgram.org/heg/volume13/04April/FoodAsMedicine_Arugula.html.
Accessed December 17, 2018.
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