HerbalEGram: Volume 15, Issue 8, August 2018

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 American Botanical Council (ABC) would like to acknowledge ABC Chief Science Officer Stefan Gafner, PhD, for his contributions to this project.

By Hannah Bauman^a and Jenny Perez^b

^a HerbalGram Associate Editor

^b ABC Education Coordinator

Overview

Known for both their ornamental beauty and sweet and tart fruits, cherry (Prunus spp.) trees are among the 3,400 species that belong to the economically important rose (Rosaceae) family. This botanical family also includes other fruit-bearing trees such as apples (Malus spp.) and pears (Pyrus spp.), as well as herbaceous perennials like strawberries (Fragaria spp.) and brambles like blackberries (Rubus spp.) and raspberries (Rubus spp.).¹

Cherry fruits are produced by various trees and shrubs belonging to the subgenus Cerasus in the genus Prunus. (Cerasus is Latin for “cherry tree.”) The Prunus genus includes more than 430 known species, including almonds (P. dulcis) and pit-containing fruits such as plums (P. salicina), apricots (P. armeniaca), and peaches (P. persica).¹ Species in the subgenus Cerasus are characterized by flowers that are arranged in small corymbs (not singly or in raceme) and dark red fruits that are entirely smooth in appearance or have a subtle groove along one side. The leaves of cherry trees are simple, typically lanceolate, and unlobed with serrated margins, and their flowers are typically white to pink with five petals and five sepals. The fruits are botanically known as drupes: fleshy fruits surrounding a single stony seed. Of the 150 known species of cherries, the two most commonly grown commercially are the wild or sweet cherry (P. avium) and the sour cherry (P. cerasus).¹

The sour cherry is a hybrid between the sweet cherry and P. fruticosa, a wild cherry species.²

Sour cherry trees are half the size of sweet cherry trees and grow to about 16 feet tall.³ Cultivated sour cherry trees are thought to have ancient origins from Armenia and areas near the western Caspian Sea.¹ Throughout Europe, the pits of wild cherry species have been uncovered in settlements that date back to the Bronze Age (around 3200 BCE). Records indicate that by 800 BCE, cherry trees were being cultivated in Turkey.¹ By 300 BCE, sour cherry trees were being cultivated in Greece and spread throughout Europe thereafter by the Romans.^1,2

Sweet cherry is derived from cultivars of a wild cherry native to temperate Europe and Western Asia.^1,2 Sweet cherry trees are large and can reach a height of 36 feet. The tree’s white flowers appear in clusters of up to five.² Unlike the sour cherry, sweet cherry requires cross-pollination for fruit production, and therefore requires the planting of two or more cherry trees.² The fruits of P. avium are firm, heart-shaped to almost globular, and vary in color from yellow to red to crimson-black. Unlike sour cherries, sweet cherries have a high sugar and low acid content.^1,3

Historical and Commercial Uses

The cultivation of cherry trees became popular in the 16th century under King Henry VIII of England. He and his gardener, Richard Harris, are commonly given credit for improving cherry production by developing cultivars.^1,4 The “Kentish Red” cherry variety was one of two dozen cultivars developed by Kentish growers by the mid-17th century and the first sour cherry variety planted in Massachusetts when European colonists arrived in the Americas.¹ Today, there are more than 1,000 cherry cultivars: approximately 900 sweet and 300 sour.⁴

Aside from their fruits, various species of cherry trees have been grown for their ornamental value (such as Japanese cherry [P. serrulata], which is frequently depicted in Japanese art) and for fine furniture and wood construction (such as black cherry [P. serotina]).¹

Black cherry bark traditionally was used by Native American, including the Cherokee, Delaware, Iroquois, and Ojibwa, as a remedy for coughs and colds.⁵ Black cherry bark contains prunasin, a cyanogenic glycoside that suppresses the cough reflex.⁶ Western and European herbalists continue to use wild cherry bark in small amounts as a cough suppressant and for lung support. The Cherokee and Iroquois also used black cherry bark to treat diarrhea and “toxic” blood conditions that were thought to contribute to rheumatoid arthritis, gout, and allergic reactions.⁵

In Ayurveda and traditional Chinese medicine, cherries are considered to be astringent and “blood-building,” and the fruits are used to remove excess body acids and reduce blood stagnation. In these systems of medicine, daily cherry consumption is indicated for easing the pain and inflammation associated with gout, arthritis, and rheumatism.^7-9

ABC Chief Science Officer Stefan Gafner recalled a non-therapeutic use of cherry pits from his youth: “When I was young, cherry pit pillows were quite commonly used in rural areas of Switzerland,” Gafner wrote (email, August 15, 2018). “We used them mainly to protect our buttocks from overheating while sitting on the wood stove.” Cherry pit pillows have been used as cold or hot compresses because they have a natural inner air chamber surrounded by a heat-conducting outer layer, which enables heat to be released slowly over time.

Phytochemicals and Constituents

Cherries are considered a nutrient-dense, low-calorie fruit and provide important nutrients such as beta-carotene, vitamins C and E, potassium, magnesium, folate, iron, and fiber.^9-11 A one-cup serving of pitted cherries contains about 10.8 g of vitamin C, 3 g of fiber, and 342 mg of potassium.¹¹

Cherry fruit contains significant amounts of polyphenols and flavonoids, including anthocyanins, hydroxycinnamic acid, and quercetin.¹⁰ When consuming the whole fruit, there appears to be a synergy between the antioxidant effects of vitamin C, carotenoids, and anthocyanins, and this is thought to contribute to their health-promoting effects.⁹

Anthocyanins are phenolic compounds that make up the largest group of water-soluble plant pigments and give orange, red, and blue colors to vegetables, flowers, and fruits.^12,13 A dark fruit is indicative of a high anthocyanin content.¹⁴ Sweet cherries have a higher anthocyanin content than sour cherries, with cyanidin glycosides accounting for more than 90% of sweet cherry’s total anthocyanin content.^10,14 Cyanidin glycosides have numerous health-promoting properties, including vasoprotection and inflammation modulation, and they also provide anti-obesity and anti-diabetes benefits.¹⁵

Hydroxycinnamic acid is an antioxidant substance that accounts for about 40% of the total phenolic compounds present in cherries.¹⁰ Hydroxycinnamates can reduce oxidative stress in the body, inhibit low-density lipoprotein (LDL) oxidation and tumor growth, and decrease the formation of nitrosamines and other mutagenic compounds.

In addition, cherries are also a good source of tryptophan, serotonin, and melatonin, which play important roles in mood balance and cognition.¹⁶ In humans, melatonin has been shown to support regular sleep cycles and circadian rhythm, and improve immune system function, and slow processes associated with aging.¹⁷ Melatonin has potent antioxidant properties and can freely cross cell membranes, mitigating free radical damage both inside and outside the cell, thereby significantly reducing oxidative stress.^1,10,16-17 Melatonin can increase plasma levels of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF α), both of which promote non rapid-eye-movement (REM) sleep. Sour cherries have a higher level of melatonin than sweet cherries.

Modern Research and Potential Health Benefits

Long considered a “superfruit,” cherry is associated with several health benefits. Research on cherry’s bioactive compounds suggests that this fruit has the potential to prevent cardiovascular disease, diabetes, and other chronic inflammatory diseases.

Oxidative stress and inflammation are among the primary causes of chronic inflammatory diseases, such as diabetes, heart disease, and arthritis.¹⁶ Cherry consumption has been associated with reductions in oxidative stress, inflammation, glucose modulation, and inhibition of uric acid production.¹⁰ Polyphenols, melatonin, carotenoids, and vitamins E and C all contribute to cherry’s antioxidant and anti-inflammatory properties.¹⁶

Inflammation

A 2018 meta-analysis of clinical studies that assessed the benefits of cherry fruit consumption found that sweet or tart cherry consumption was correlated with reductions in oxidative stress and inflammation.¹⁶ In most human studies, the daily dose of cherries ranged from 45 to 270 cherries (an anthocyanin equivalent of 55-720 mg/day) and were served as either a single dose or split into two or three doses, and the duration of studies ranged from five hours to three months.¹⁶ Eleven of 16 clinical studies that investigated the effects of cherry or cherry product consumption showed significant decreases in inflammatory markers, including plasma C-reactive protein (CRP) levels, TNF α, interleukin 6 (IL-6), interleukin 8 (IL-8), and nitric oxide (NO).¹⁶

The cyanidin content in cherries has the ability to inhibit cyclooxygenase (COX) enzymes, which perpetuate the inflammatory response.¹⁰ Many over-the-counter (OTC) pain medications work by inhibiting COX-1 and COX-2 enzymes. When compared to ibuprofen and the nonsteroidal anti-inflammatory drug naproxen, anthocyanins derived from cherries were able to inhibit COX-1 and COX-2 inflammatory cascades just as effectively as the OTC pain relievers.¹³ Of all fruits tested for inflammation modulation, the anthocyanins derived from raspberries and sweet cherries had the strongest inhibitory effects on COX-1 and COX-2.¹³

Additionally, cherry’s flavonoids have been shown to reduce oxidative stress and β-amyloid plaque formation (a process believed to contribute to Alzheimer’s disease).¹⁰ Cherry’s phenolic compounds have a potential role in protecting neuronal cells and thus neurological function as well.¹⁰

Cardiovascular Disease

Cardiovascular disease is responsible for one in four deaths in the United States, killing approximately 610,000 people annually.¹⁸ Diets rich in colorful, flavonoid-rich fruits and vegetables are correlated strongly with a lower incidence of cardiovascular disease. Additionally, fruits such as cherries that are high in potassium have been shown to support cardiovascular health and can help reduce risk of hypertension and stroke. Since 2006, Kelley et al. have evaluated the effects of cherry anthocyanin compounds on heart health in multiple human studies. Results indicate that individuals with cherry-enriched diets had reduced triglycerides, total cholesterol, fasting glucose, and insulin levels, as well as elevated high-density lipoprotein (HDL) levels and antioxidant capacity of the blood.⁹

In human studies that examined the effects of cherry consumption on blood pressure, the greatest reductions in both systolic blood pressure (SBP) and diastolic blood pressure (DBP) occurred when the doses were higher and less frequent.¹⁶ For example, with a 300 mL dose of cherry juice, both SBP and DBP decreased within two hours, and blood pressure returned to baseline at six hours. However, when doses were divided into three 100-mL increments at 0, 1, and 2 hours, there was no decrease in either SBP or DBP at two or six hours. The reduction in blood pressure was determined to be caused by a peak increase of circulating anthocyanin metabolites in the blood.¹⁸

Elevated CRP level is associated with and an increased risk of heart disease. In a 2006 clinical trial, healthy men and women who supplemented their diets for four weeks with a daily dose of 280 g fresh cherries (equivalent to 45 fresh pitted cherries) experienced a reduction in NO, a key regulator of vascular integrity, and a 24% reduction in CRP levels. The authors noted that these changes may be associated with a significant reduction in the risk of atherosclerosis.^18,19

Exercise-Induced Muscle Damage and Recovery

The tart Montmorency cherry cultivar has been investigated in human studies for its ability to improve muscle soreness and overall recovery from strenuous exercise.²⁰ In a clinical trial, athletes were able to more rapidly recover their strength when consuming cherry juice post-marathon when compared to placebo. All exercise-related studies evaluated by Kelley et al. used a tart cherry juice concentrate that delivered a dose equivalent to approximately 50 to 270 cherries daily.¹⁶ Researchers concluded that the high concentrations of anthocyanins in Montmorency tart cherries are responsible for reducing post-exercise inflammatory and oxidative stress responses thereby protecting athletes from decreased muscle function following strenuous exercise.²¹ For athletes who are required to perform in back-to-back competitions, consuming tart cherry juice post-strenuous exercise may help maintain strength and stamina.

Diabetes

Oxidative stress causes numerous complications in diabetic patients. Antioxidants, such as quercetin and anthocyanins present in cherries, have the potential to modulate these symptoms.¹⁰ Studies have shown that anthocyanins play a role in reducing insulin resistance and glucose intolerance as well as improve insulin secretion in response to varying glucose loads. Results from human, animal, and in vitro studies suggest that anthocyanins can decrease blood glucose by slowing glucose production from complex carbohydrates, and this in turn reduces hepatic glucose output, decreases glucagon production by pancreatic α cells, and increases hepatic glucose uptake and insulin production by pancreatic β cells.¹⁶

The most commonly used method for monitoring the effectiveness of diabetes treatments is to measure hemoglobin A1c (HbA1c) plasma values.¹² In human studies, the consumption of cherries and cherry products resulted in decreased HbA1c, very-low-density lipoprotein (VLDL), and triglyceride levels in both diabetic and obese patients.¹⁶ A 2008 study of diabetic women given 40 mL of tart cherry juice daily for six weeks demonstrated a significant reduction in HbA1c and lowered fasting blood glucose (FBG) levels by 8%, though FBG reduction was not statistically significant.¹⁶ Additionally, when a 600 mg dose of anthocyanins was given daily to diabetic patients for two months, the treatment appeared to prevent damage to blood vessels and capillaries, as well as the abnormal protein production associated with retinopathy, a serious complication of diabetes.⁹

The glycemic index is used by the American Diabetes Association as a guide for selecting fruits and vegetables that are metabolized more slowly, thus preventing problematic fluctuations in blood glucose levels.²² Foods with a low glycemic index release glucose slowly and steadily and, when consumed regularly, help promote weight loss. Studies have shown that cherries have a glycemic index of 22, which is fairly low for a fruit.¹⁰

Arthritis, Gout, and Associated Risk Factors

One of the earliest known human studies to explore the health benefits of cherry fruit was conducted in 1950 on patients with gout.¹⁶ Results indicated that cherry consumption helped reduce symptoms of arthritis and restore plasma uric acid (UA) levels, and at least four of the patients reported greater mobility in the joints of both fingers and toes. Subsequent studies by Jacob, et al. found that cherry fruit consumption reduced blood levels of inflammatory and oxidative stress markers. The plasma UA levels were significantly reduced at five hours post-consumption, but not at 1.5 or three hours, when compared to baseline.²³

In a 2003 pilot study designed to assess plasma urate levels before and after consuming an anthocyanin-rich food, 10 healthy women ate a single 280-gram dose of pitted sweet cherries and blood samples were collected at 1.5, three, and five hours post-consumption. Five hours after consuming cherries, there was a significant mean reduction in plasma urate levels, demonstrating a prolonged anti-inflammatory effect that was not shown with grape (Vitis vinifera, Vitaceae), strawberry (Fragaria x ananassa, Rosaceae), or kiwifruit (Actinidia deliciosa, Actinidiaceae). ^10,23

A crossover study on 633 gout patients given fresh cherries or cherry extract over a two-day period was correlated with a 35% lower risk of gout attacks compared to those who consumed no cherries at all.¹⁷ When cherry consumption was combined with allopurinol (Zyloprim; Prometheus Labs, Inc., San Diego, California), a pharmaceutical medication used to reduce UA levels, there was a 75% reduction in risk of gout attacks. Furthermore, participants who used allopurinol and did not consume cherries experienced 792 hazard periods, a two-day period of time prior to a recurrent gout attack, as opposed to 45 hazard periods experienced by those who combined cherry consumption with allopurinol.¹⁷

Sleep, Mood, and Cognitive Function

A 2012 clinical trial was the first to report evidence that supplementation with tart cherry juice may improve quality of sleep by increasing exogenous melatonin available to the body.²⁴ In a randomized, double-blind, placebo-controlled crossover study, 20 healthy individuals consumed either placebo or 30 mL tart Montmorency cherry juice diluted in 200 mL water twice daily (within 30 minutes of waking and 30 minutes before the evening meal) for seven days. Each 30 mL serving of tart cherry juice contained 90-100 tart cherries. The concentration of melatonin in the tart cherry juice was equivalent to a dose of approximately 42.6 µg per serving or approximately 85.2 µg daily.²⁴ Upon completion of the study, results indicated an increase in circulating blood levels of melatonin, and participants reported modest improvements in sleep time and quality of sleep.^24,25 Studies on melatonin supplementation for disturbed sleep patterns and insomnia indicate that 0.5-5 mg is required daily.

Sweet cherry consumption also has been studied for improving both quality and quantity of sleep. Within three days of beginning the study, noticeable effects on sleep were detected when patients consumed 141 g or 25 cherries daily while the sleep enhancing effects of tart cherry consumption (240 mL tart cherry juice or approximately 100 cherries daily) were not detectable until day five. Studies using sweet cherries also reported improved mood, lowered anxiety, and decreased urinary cortisol.¹⁶ These findings indicate that cherry fruit or juice may be a natural sleep aid for those suffering from chronic or situational insomnia.

Consumer Considerations

Fruits and vegetables that have thin skins are prone to the potential accumulation of pesticide residues. Cherries, with their thin, anthocyanin-loaded skin, are listed among the 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 (EWG).²⁶ According to its annually gathered data, conventionally grown cherries had an average of five detectable pesticides. Additionally, 30% of cherry samples tested contained iprodione, a carcinogenic pesticide that is banned in Europe.²⁶ Due to the cumulative nature of fat-soluble pesticide residues within the body, purchasing and consuming organically grown cherries is strongly recommended whenever possible.

The levels of anthocyanins and phenolic compounds in cherries vary depending on the cultivar, cultivation methods, ripening stages, harvest time, and post-harvest handling and storage conditions.¹⁴ Depending on the type of cherry cultivar, fresh sweet cherries can be stored in the refrigerator for two to four weeks.¹⁴ After six months of freezer storage, more than 75% of Bing cherry anthocyanins were lost. For canned cherry fruit, all analyzed cultivars showed a 21-24% decrease in anthocyanin concentrations when processed with heat, high acid, and sugar concentrations; however, about 50% of anthocyanins and polyphenols were leached from the fruits into the syrup and were nonetheless retained within the can.¹⁰ Despite the seasonal availability of fresh cherries, modern processing techniques do not cause a significant loss in total anthocyanins and phenols, allowing for year-round accessibility to the benefits of cherries.²⁷

Nutrient Profile¹¹

Macronutrient Profile: (Per 1 cup pitted cherries [approx. 154 g])

97 calories
1.63 g protein
25 g carbohydrate
0.3 g fat

Secondary Metabolites: (Per 1 cup pitted cherries [approx. 154 g])

Very good source of:

Vitamin C: 10.8 mg (12% DV)
Dietary Fiber: 3.2 g (10.7% DV)

Good source of:

Potassium: 342 mg (7.3% DV)

Also provides:

Manganese: 0.11 mg (4.8% DV)
Vitamin B6: 0.08 mg (4.7% DV)
Magnesium: 17 mg (4% DV)
Riboflavin: 0.05 mg (3.8% DV)
Thiamin: 0.04 mg (3.3% DV)
Iron: 0.55 mg (3.1% DV)
Vitamin K: 3.2 mcg (2.7% DV)
Phosphorus: 32 mg (2.6% DV)
Vitamin A: 99 IU (2% DV)
Calcium: 20 mg (1.5% DV)
Folate: 6 mcg (1.5% DV)
Niacin: 0.24 mg (1.5% DV)
Zinc: 0.11 mg (1.1% DV)

Provides trace amounts:

Vitamin E: 0.11 mg (0.7% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet.

Image credits (top to bottom):

Sour cherry fruit on the tree. ©2018 Steven Foster.
Illustration of cherry by Carl Axel Magnus Lindman from Bilder ur Nordens Flora, 1901.
Sour cherry fruit. ©2018 Steven Foster.
Cherry tree in bloom. Image courtesy of Benjamin Gimmel.
Sour cherry fruit. ©2018 Steven Foster.

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