June 2015 Issue
The Allure of Exotic Berries
By Jasenka Piljac Zegarac, PhD
Today's Dietitian
Vol. 17 No. 6 P. 32
Studies show they're chock full of nutrients, but more research is needed to determine their tangible health benefits.
Although you won't find them in most mainstream grocery stores, exotic berries such as açaí, acerola cherry, aronia, goji, noni, and pichuberry have been incorporated into a variety of consumer products over the past decade, from juices and instant drinks to smoothies and yogurts. The growing number of functional food products and supplements containing exotic berry ingredients has created its own market trend. Health-savvy, educated consumers are putting into practice Hippocrates' time-honored wisdom: "Let food be thy medicine and medicine be thy food." They're making food choices based not only on nutritive value, but also on perceived health benefits.
"I believe consumers are becoming increasingly enlightened as to the health-protective properties of phytoactive compounds in foods, and the potential to benefit from food intake rather than rely on drugs,'' says Mary Ann Lila, director of the Plants for Human Health Institute and a David H. Murdock distinguished professor at North Carolina State University. Lila also believes that the appeal of exotic berries is due to the good background knowledge on their use, the high phytochemical content, including anthocyanin pigments (much higher than in many commercial berries) in some of the varieties, and the fact that the appeal of something "unknown" seems more promising than something with which we're familiar.
Some exotic berries are imported from the floodplains of the Amazon, while others are brought in from the sun-drenched fields of the Mediterranean, and the far-off lands of Asia. Others are grown and harvested domestically, in California, Hawaii, or Florida. They vary in size, shape, color, texture, and aroma, but have one thing in common—each has a history of its own and offers a unique taste of the unknown.
Following is a discussion of some of today's most popular exotic berries, the nutrients they contain, and the biological effects they exert.
Açaí
Açaí palm trees (Euterpe oleracea) are native to tropical Central and South America where they grow in floodplains and swamps.1 They flourish in warm and humid climates and prefer slightly acidic soils. They can grow to an impressive 20 to 30 m in height and bear fruit in clusters that can contain up to 900 berries.2 Açaí fruit, also known as palm berries, are similar to blueberries in appearance. Mature palm berries are about 1 to 2 cm in diameter and deep purple in color, with seeds constituting about 80% of the fruit.1 The taste of the berries has been described as a blend of chocolate and berries, with a metallic aftertaste.
Although açaí fruit is consumed as a food and beverage ingredient in Brazil, and has a long tradition of use in South America, its nutrient and phytochemical composition has been evaluated only recently. A study published in 2006 found that 100 g of freeze-dried açaí fruit and skin powder contained 534 kcal, 52 g of carbohydrates, 8 g of protein, and 33 g of total fats.3 The tested freeze-dried powder was rich in fatty acids, especially oleic, palmitic, and linoleic acids. Total unsaturated fatty acids composed 74% of all fatty acids. In the same study, 19 amino acids were found in freeze-dried açaí berries, as well as several sterols, including campesterol, sigmasterol, and β-sitosterol. Anthocyanins, proanthocyanidins, and other flavonoid constituents were the main phytochemical compounds detected, with cyanidin 3-glucoside and cyanidin 3-rutinoside identified as the two predominant anthocyanins.
Antioxidant effects of açaí have been largely attributed to phenolic compounds and their conjugate forms. In one study, a juice blend containing palm fruit as the main ingredient had demonstrated in vivo antioxidant and anti-inflammatory effects.4 In another study, a different group of researchers conducting an in vitro study observed that palm berries inhibit the activity of cyclooxygenase (COX)-1 and -2, enzymes responsible for the formation of prostanoids in the inflammatory response.5
Acerola Cherry
Malpighia emarginata, commonly known as acerola cherry, Barbados cherry, or French cherry, is an upright growing evergreen shrub belonging to the Malpighiaceae family.6 It grows an average 4.6 m in height and is believed to be native to Central America, northern South America, and the Caribbean islands.2 Today, acerola plants are grown in warm, tropical climates of the east Caribbean, Florida, Hawaii, Barbados, Puerto Rico, Taiwan, and Brazil. They're also well adapted to southern California's coastal and inland climate.6
Acerola cherries are well known as one of the best natural sources of vitamin C, which also makes them commercially interesting.7 In addition to high ascorbic acid content, acerola fruit is rich in bioflavonoids (anthocyanins, proanthocyanidins, flavonols, and catechins) and carotenoid pigments.2 The four major carotenoids identified in acerola cherries include β-carotene, β-cryptoxanthin, lutein, and violaxanthin. Research has shown that the carotenoid content in acerola cherries increases with fruit maturity.8 A 2005 study reported antioxidant properties of acerola fruit juice,9 while another in 2003 pointed to anti-inflammatory activities of acerola extracts.10
Acerola cherries are bright red and similar in size to regular cherries.6 In addition to being consumed fresh, acerola cherries are used to make juices, compotes, and jellies.2
Aronia
The Aronia genus consists of two species—Aronia melanocarpa (A melanocarpa), commonly known as black chokeberry, and Aronia arbutifolia (A arbutifolia), commonly known as red chokeberry. Speciation in this genus isn't completely understood, and it's suspected that Aronia prunifolia (purple chokeberry) is a hybrid between A arbutifolia and A melanocarpa.11 Aronia plants are deciduous shrubs, native to North America and distributed across the Northeastern United States and the Great Lakes region. They're well adapted to cold climates and higher elevations, such as the Appalachian Mountains.12 Red chokeberry shrubs grow between 6 and 10 ft tall while their black counterparts typically reach a mature height of 4 to 8 ft. Conversely, black chokeberry fruits are slightly larger in size (≥0.3 in) and ripen earlier (late July to August) than their red counterparts (≤0.3 in; September to October).11
More data on cultivation, nutrient, and phytochemical contents are available for black as opposed to red chokeberries. Black chokeberries are a good source of fiber, sugar (glucose and fructose), and phenolic compounds (procyanidins, anthocyanins, and phenolic acids), which are believed to be responsible for their distinct antioxidant properties.12,13 In addition, Aronia juice has been found to have a relatively high average content of potassium and zinc, as well as marked levels of sorbitol.13
The biological effects of Aronia fruit extracts, juice, and other preparations have been investigated in animal and human studies.12 To highlight a few, antihypertensive effects were observed in men with mild hypercholesterolemia who consumed chokeberry juice for six weeks.14 Another study found a reduction in cardiovascular risk markers in patients who had a myocardial infarction and were treated with a combination therapy including a statin and flavonoid-rich extract from chokeberry fruits.15 Hypoglycemic effects of black chokeberry fruit juice were reported in a study conducted in rats with streptozotocin-induced diabetes,16 while gastroprotective effects of red pigments in black chokeberry fruit were observed in acute gastric hemorrhagic lesions in rats.17
Black chokeberries are the size of large blueberries and are inedible raw because of their astringency, which is why they're often consumed processed in the form of jams, jellies, and syrups, or added as flavorings and colorants. It's difficult to find fresh aronia berries for sale in the United States, since the aronia industry is still in its infancy.
Goji
The fruit of Lycium barbarum (L barbarum) and Lycium chinense (L chinense) often is referred to as goji, Chinese boxthorn, or wolfberries. Both species belong to the Solanaceae family, which also includes the common potato and tomato plants. L barbarum and L chinense plants are deciduous woody perennial shrubs that grow between 1 and 3 m high; L chinense is typically slightly shorter.18 L barbarum is widely distributed in the Mediterranean, and Central and Southwest Asia, while L chinense grows in East Asia, South China, Korea, and Japan. Most of the commercially grown wolfberries originate from China.
Goji berries are oblong, orange to dark red in color, and up to 2 cm in diameter.18 The main nutritive and phytochemical constituents of goji fruit include polysaccharides, fatty acids, vitamins, polyphenols, and carotenoids.
Polysaccharides and proteoglycans constitute about 23% of goji dried fruit,19 while vitamin C content of 42 mg/100 g is comparable to that of fresh lemons.18 Zeaxanthin dipalmitate constitutes 49% and 56% of the total carotenoids in the L barbarum and L chinense species, respectively.20
Among the many identified constituents of goji fruits, bioactive polysaccharides have received the most attention in the scientific community.21 In animal studies, polysaccharides from goji were shown to improve antioxidant status in aged mice,22 exhibit hypoglycemic and hypolipidemic effects in alloxan-induced diabetic or hyperlipidemic rabbits,23 boost immune function in mice,24 and protect DNA in rats.25 Antioxidant effects of L barbarum polysaccharides also were confirmed in a 30-day randomized, double-blind, placebo-controlled clinical study conducted in 50 healthy Chinese adults.26 However, two case studies have pointed to possible interaction between L barbarum constituents and warfarin, which may present a risk for patients treated with this drug.27,28
Goji berries taste bittersweet and can be eaten raw or dried, or added to numerous meat and vegetable dishes.18
Noni
Morinda citrifolia L, also known as the noni plant, belongs to the Rubiaceae family. Other common names for the plant and its fruit include Indian mulberry, nonu, and "cheesefruit" (Australia).29 There are approximately 80 species in the Morinda genus and all grow in tropical climate zones.30 Noni is believed to be native from southeast Asia to Australia and is distributed throughout southeast Asia and Australia, India, Eastern Polynesia, and Hawaii.31
The noni plant is an evergreen shrub 3 to 6 m high that also can grow as tall as a tree. It's characterized by tubular white flowers and ovoid fruit whose lumpy surface is divided into polygonal sections.29 The mature fruit can reach up to 12 cm in size and has an unpleasant odor and taste, earning the name "cheesefruit." When ripe, noni fruit are light yellow or almost white in color. The root extracts of the plant traditionally have been used for their yellow or red dye.
In addition, the plant has been used in traditional folk medicine in Polynesia for more than 2,000 years for various ailments.32 While the Polynesians used various combinations of the whole noni plant for herbal medicine, today, the most used preparation in alternative medicine is noni fruit juice.31 Unfermented noni juice contains approximately 10% of dry matter that consists mainly of glucose and fructose (3% to 4% each), protein (0.2% to 0.5%), and lipids (0.1% to 0.2%).30
Pure noni fruit juice has been reported to contain 33.65 mg/100 g of juice of vitamin C, 10.5 mg/100 g of juice of sodium, and 10.1 mg/100 g of juice of calcium.33
Due to its strong, unpleasant smell and bitter taste, noni fruit isn't widely regarded as palatable when consumed fresh and often is added to curry dishes. It's readily available in the Pacific Islands.
Pichuberry
Pichuberry is the fruit of the Physalis peruviana L plant, which belongs to the Solanaceae family. Although it isn't closely related to cherries or gooseberries, some common names for the plant include Inca berry, golden berry, Cape gooseberry, and Peruvian cherry. Pichuberries are native to the Peruvian Andes region and, more specifically, the mountains of Machu Picchu. Today, it's grown all over the South American Andes.34 It's also cultivated to varying degrees in France, India, Madagascar, Australia, New Zealand, and the Pacific islands.
The plant is an herbaceous, perennial semishrub adapted to subtropical climates. It grows to an average height of 0.6 to 0.9 m, although some plants may reach up to 1.8 m in height.34 The fruit is yellow or light orange in color and has an ovoid shape with a diameter between 1.25 and 2.50 cm. The inside of the fruit is filled with small seeds; the outside is protected by the calyx, resembling a small lantern.
The berries are juicy and sweet, with a tart aftertaste, and are a great source of vitamins A, C, and D, and the B-complex vitamins B1, B6, and B12. "Just 3.5 oz of pichuberries contain 13% of the RDA [recommended dietary allowance] for niacin, 18% of the RDA for vitamin C, 37% of the RDA for vitamin A, and 39% of the RDA for vitamin D," says Manuel Villacorta, MS, RD, coauthor of Peruvian Power Foods: 18 Superfoods, 101 Recipes, and Anti-aging Secrets from the Amazon to the Andes and author of Whole Body Reboot: The Peruvian Superfoods Diet to Detoxify, Energize and Supercharge Fat Loss. "Truly a culinary treat, the pichuberry brings a unique flavor profile that enhances dishes both savory and sweet. Its versatile fruit can be eaten plain in everything from breads to salads and desserts. You can add raw pichuberries to yogurts, smoothies, waffles, and more," Villacorta says. "In addition, pichuberries have a low glycemic index of 25."
They also contain a large group of naturally occurring bioactive compounds called withanolides, Villacorta says, which are believed to contribute significantly to the functional properties of pichuberries. Nevertheless, clinical research still needs to substantiate the fruit's empirically observed medicinal properties.34 One recent study reported hypoglycemic effects of pichuberries. Eating the fruit reduced blood glucose levels after 90 minutes postprandial in young adults.35
Due to recent efforts to make fresh pichuberries available on the US market, they now can be found in certain health food and grocery stores on the West Coast.
Scientists' Perspective
Research has shown that exotic berries abound in bioactive compounds with potential health benefits. However, a recent study emphasizes that the long-term impact of exotic berry consumption on specific populations and their functional effects haven't been thoroughly investigated.36 Furthermore, the mechanisms of action of bioactives from exotic berries isn't fully understood. "In vitro and animal studies give us insights into mechanisms of action, and thus are crucial to complete.
Until we know how a phytoactive compound works in a health intervention, it's very difficult to conjecture on how we can recommend it for human intake and protection," Lila says. "Also, these studies are magnitudes of order less expensive than human studies; however, increasingly we're conducting excellent clinicals (human studies) using berries as the intervention, with excellent results for sports performance, cognitive function, metabolic syndrome, and more. These clinicals have been performed on commercially available berries that have recognized health components.
"For example," Lila continues, "frozen wild blueberries, which are widely available and are exclusively grown in North America, are underrated. These berries have a tremendous impact on human health maintenance and are readily available to American consumers."
The rise in popularity of exotic berries should be accompanied by additional research incentives aimed at investigating the efficacy, safety, and potential interactions of berry constituents with other dietary components.36 However, certain practical obstacles first must be addressed. "It would be difficult to acquire sufficient volumes of 'exotic' berries to do a clinical trial, unless the berries were in dried form or something, and frankly the drying might degrade the health benefit potential," Lila says. "Frozen/fresh or lyophilized berries will preserve the health protective constituents, and you need large volumes to conduct a human intervention."
— Jasenka Piljac Zegarac, PhD, is a scientist and freelance writer based in Okemos, Michigan (www.thescientistwriter.com). She has coauthored more than 30 peer-reviewed scientific journal articles and the popular science book Zinfandel: A Croatian-American Wine Story.
References
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Recipe
Pichuberry Guacamole
Serves 2 to 4
Ingredients
1 avocado
3 oz pichuberries (2 oz crushed and 1 oz quartered)
2 T chopped cilantro
2 T diced red onion
Salt to taste
Directions
Slice the avocado in half and remove the pit. Place the avocado meat in a bowl and add the additional ingredients. Thoroughly mix and enjoy.
Nutrient Analysis per serving
Calories: 101; Carbohydrates: 10 g; Fat: 7 g; Sodium: 23 mg; Dietary fiber: 3 g; Protein: 2 g