Colin Michie (FRCPCH FRSPH RNutr) & Pamela L. Duarte
American University of the Caribbean, St Martin
A young Scottish naval captain, Colin Michie, was killed in 1759 by the French. He had led HMS Newcastle into battle in the seas off Pondicherry in eastern India. This was an early skirmish in the global Seven Years’ War during which the British extended their colonial powers. The war was about trading outposts and had significant impacts on all French colonies. In Pondicherry, the Indian textiles represented important potential wealth. Family legend has it that Colin, one of my ancestors, had discovered a way to dry Indian mango and bring it back to Aberdeen in Scotland. We shall never know. The lack of storage methods made transporting mangoes on slow sea voyages challenging. Mangoes imported to American colonies in the 17th century were pickled. Other pickled fruits came to be called “mangoes” by association, in particular bell peppers. By the 19th century, mango-shaped patterns were being copied and printed on scarves by Scottish weavers in Paisley, although the real fruit were extremely rare. Happily, a more recent ancestor, my grandfather, developed a method to stock pickled mangoes on his ship returning through the Suez Canal to surprise his family.
Mangoes are Popular
Our favourite fruits change – every generation develops its particular sources of enjoyment. Markets in tropical fruit have shown spectacular growth over the last ten years. The rapid rise in our demands for the aromatic, richly juicy, and colourful mango has been quite striking! The world has been enticed by the wide variety and use of this exotic fruit. Markets have been developed for pomegranate, guava, passion fruit, mangosteen, jackfruit, and all manner of berries, but of all these delectable choices, mangoes are the cream of the crop. Global trade in fruits surpasses that of vegetables with 5–10% of fruit being traded on international markets, often as juices. This expansion is supported by new technologies including improved freezing, drying, and organic farming. New discussions regarding eating habits such as flexitarianism, micronutrients, superfoods, nutraceuticals, and functional foods have all come into fashion and focus. The juice trade has also seen a massive development in recent years.
Mango exports generate significant finance for Caribbean countries. For instance the Dominican Republic grows some 100 varieties of mango, exporting 17 million kilograms annually. Their varieties include the Banilejo (named after the city Baní), Colón (named after Christopher Columbus), and Gota de Oro (“drop of gold”). As the Dominican mango capital, Bani hosts a mango festival, “La Feria del Mango Banilejo,” every June. Production of mangoes in 2017 was the highest ever and it is expected to increase further, particularly from India, China, Mexico, and Tanzania. Regardless of their size, whether small fruit at a grade 4 weighing about 200 grams or a larger grade A2 weighing about 350 grams, mango packs punches of previously unrecognised richness.
The Powerhouse Inside that Golden Fruit
So, mangoes are terrific, whether as fruit, juice, pickled, dried, as jam, or ice cream. However, the pharmacological magic of mangoes appears more powerful than even the countless recipes from celebrity chefs and amateur cooks alike. This topic has begun to excite researchers and pharmacological molecular mango mapping is an expanding field.
What are the nutritional metrics behind mango–mania? Mangoes contain carbohydrates, several grams of fibre, are fruit-full of fascinating phytochemicals, and have acids such as citric, malic, and tartaric acids. There is little fat in mango flesh; they do however contain some essential fatty acids. Fresh mango is a useful source of minerals such as potassium, calcium, magnesium, copper, and iron while containing little sodium. Mango is an excellent source of vitamins such as vitamin C, B (including folic acid), E, K, and A (with about 25 provitamin A carotenoids. Producers wishing to maximise health–promoting compounds in mangoes have developed several strategies. Some cultivars contain more nutrients than others. Moreover, genetic engineering has increased mango shelf life by reducing their production of ethylene, a gas that quickens ripening. Routine spraying of the fruit with iron sulphate a month before harvest, storage of the mature green fruit at 5 degrees after harvesting, and exposure to elicitors such as nitric oxide before waxing the fruit can all greatly increase levels of phytochemicals present in mango.
Several cyclical compounds, known as polyphenols, are found in mango fruit and fruit juice, as well as in its leaves and bark. These include compounds with positively romantic, other-worldly names such as quercetin, kaempferol, catechins, mangiferin, gallotannins, and lupeol. All these compounds are being actively evaluated as valuable nutraceuticals, which are nutrients that have useful pharmaceutical effects. What is predictable is that various mango polyphenol activities, ranging from antioxidant to anti-inflammatory capabilities, are likely to be valuable directly to us, and possibly indirectly by beneficially interacting with our gut bacteria.
Mango kernel yields an oil that solidifies to fat or butter at cool room temperatures. This is ideal for skin products or ice cream use. Furthermore, mango oils also contain many of the polyphenols found in the fruit. Therefore, mango oil is an underexploited tropical product that is likely to find its way into numerous future technologies. Processed mango kernel can also be heated to form a particularly useful form called “biochar,” or a substance akin to charcoal. This has been used to enrich soils for mango plantations and other agricultural systems, so nothing is wasted from large crops of mango trees.
Mangoes are so Sweet: Can they be Healthy?
Some say that mangoes are too sweet and they’ll raise your blood sugar. Are they suitable as a guilt-free snack? A careful Nigerian study examined blood glucose changes in healthy adults after eating several different fruits. Mangoes do raise blood sugar levels, but not to a particularly high level and not for very long. This is probably because of the fibre mangoes contain, as well as their polyphenols. Mangoes contain both soluble and insoluble indigestible fibres. Both these types of fibre slow the absorption of sugars. Soluble fibres draw water into the bowel and are also prebiotic since gut bacteria utilise them. Hence, mangoes ensure that bowel bacteria remain happy! Mangoes also contain a fruit sugar, fructose, that is stored in the liver rather than in muscle. Unlike glucose, fructose does not raise insulin or leptin levels and therefore does not stop you from feeling hungry. We do not currently know which specific mangoes or what levels of ripeness are best for blood sugar levels. Therefore, it would be best to eat mango in moderation, particularly if you already have diabetes or blood sugar that runs high. A helpful tip that holds true for mangoes and other fruits is that to minimise so-called sugar “spikes,” it is best to avoid juices, smoothies, and dried fruit. All these forms of fruit tend to concentrate sugars and reduce the benefits of fibre found in whole fruit.
Sweetness can be measured. In the Brix scales of sweetness, one Brix degree is a gram of sugar in 100 grams of solution. Mangoes are between 6 and 14 Brix degrees, which is similar to an avocado, while pineapples are sweeter scoring between 14 and 22 Brix degrees. The energy value of a 100-gram serving of a Julie mango is 250 kJ (or 60 kcal). Green mangoes are not as sweet and are often dried to make a fruity, sour, tangy spice called, “amchur” or “amchoor.” This mango-derived spice is used frequently in Indian cuisine and Ayurvedic medicines. Even when not fully ripe, mangoes are full of vitamin C and amchur use came to medical attention in 1885 when it was found to prevent scurvy.
The cocktail of nutrients in mangoes also has effects on other foods eaten at the same time. Mango makes other nutrients more available, including iron, zinc, vitamins, and polyphenols, even in vegetarian diets high in phytic acids. Mango is therefore considered a functional food, like tamarind or lime juice. Whether used in a jam, toffee, custard, or dried amavat, mango delivers extra nutritional functionality to our diets.
Mangoes in Traditional Medicine
Mangifera indica, a rapidly growing shade tree, has been used in tropical regions by indigenous peoples for a range of different reasons. In the Caribbean, mango trees are often important socially – their great age and large spreading canopies lets them cool homes and offer social centres to many communities.
From a medicinal perspective, the tree has been used in Ayurvedic as well as indigenous medical systems for at least 4000 years. Common uses of the fruit in traditional herbal lore are for mouth ulcers, tooth pain, and external wounds including eczema and burns. It is also recommended for inflammation of the gut and genitourinary tract. Mango leaves and bark have been used for skin ulceration and sexually transmitted diseases. More recently, preparations from leaves and bark have been recommended specifically for diabetes and asthma, two common conditions that afflict many children and adults.
Several patterns of these traditional uses suggest that they are effective for medicinal utilization. Different ethnic groups across the globe have used mango fruit, bark, and leaves for the same purpose. With the evolution of contemporary medicine, conditions now diagnosed as diabetes or asthma have been described as responding to specific mango treatments. Finally, recently developed pharmacological assays have identified active agents in mangoes whose exact power and effects are not well-defined yet. The example of mangiferin illustrates this well.
Mangiferin’s valuable effects are numerous. This molecule reduces insulin resistance, decreases inflammation, and even kills viruses. Mangiferin also reduces the toxicity of snake venom. Recently, mangiferin has been employed to heal skin after plastic surgery. In these studies, a new technology was employed where mangiferin from mangoes was encased in a microscopic ball of lipids, a nanosphere smaller than a red cell, in order to prolong its action. At the level of a cell, mangiferin causes diverse effects by manipulating certain important energy cycles and reducing oxidative stress which in turn, decreases damage on mitochondria, the powerhouses within cells. Plastic surgeons will not be using mangiferin routinely soon, and first-line care for snake bites remains the use of an appropriate antivenom and supportive treatments. However, trials are in progress to establish the value of mangiferin for clinical treatments for all of us.
Mangiferin is not just found in mangoes. The roots of Rhizoma anemarrhenae also contain mangiferin and have been used in Chinese medicine to treat fevers and chronic infections. Mangiferin is also found in a South African honeybush, Cyclopia, that grows in the nutrient-poor fynbos of the Cape. Tea from Cyclopia has been used in local traditional medicine to treat chest and gastrointestinal problems, to reduce inflammation, and to decrease high blood sugar levels.
Those readers who run regularly will be keen to know that mangiferin has been found to improve peak and mean power sprint muscle output in young subjects. Adding quercetin, a flavonoid also found in mangoes and many other fruits and vegetables, improved this effect. In female athletes, an improvement was seen in brain oxygenation during prolonged sprinting. We must learn more about how mangiferin is useful, how much mangiferin is contained in a single mango, and what type of mango contains optimal mangiferin levels – the race is on!
Even more fascinating is the observation that mangiferin can cross the blood-brain barrier. In animal models, mangiferin crossing into the brain reduces brain inflammation. Preventing inflammation of the brain is crucial to decreasing the process of neurodegeneration which is seen in the development of dementia and Parkinson’s disease. Human tests and trials are now in progress and perhaps this molecule, alone or in combination with others, will be able to help treat these serious diseases in our elderly.
Mangoes and their Complex History
Mangoes occupy a unique place in the royalty of fruit as symbols, as well as in traditional medicine. The Mangifera indica tree most likely originated on the Malay peninsula and has been grown in much of Asia for centuries, of which India is a major producer. “Mango,” comes from a Dravidian word and “svay,” is their name in Cambodia. Mango is the national fruit of India, Pakistan, and the Philippines, and it is the national tree of Bangladesh. Mango symbolises life and happiness in Indian religions. In the Sanskrit language of Buddhism, Hinduism, and Jainism, the mango tree is one of the “kalpavriksha,” a wish-granting or transformation tree. The sun’s daughter, Surya Bai, married a great emperor after which she changed herself into a golden lotus to avoid a sorceress. This sorceress then burned the lotus, but from its ashes grew a mango tree. When a ripe mango from this tree fell to the ground, Surya emerged and was reunited with the emperor! It is said that Buddha himself meditated in groves of shady mango trees in Amrapali. Jain and Hindu traditions also include mangoes. The Great Chronicle of Ceylon described how the island converted to Buddhism following discussions about mango trees between the island’s King Tissa and Prince Mahinda. The Turkoman saint and poet, Ameer Koshru, wrote in Persian in 1330:
The choicest fruit of Hindoosthan
For garden’s pride the mango is sought
Ere ripe, other fruits to cut we ban
But mango serves us, ripe or not.
Mangoes were widely planted in India. Akbar the Great had a “lakh,” or 100 thousand, mango trees in medieval Bihar; possibly being one of the earliest documented fruit plantations. Crossbreeding was popular with royalty; the trees were later grafted and planted by colonial botanists from the 17th century. The fact that the fruit has the same name in Portuguese, Spanish, German, and English, with the French, “mangue,” being similar, indicates its cultural currency in those times. One cultivar, The Alphonso, was so famous, it was named after a colonial conqueror of Goa, the Portuguese Viceroy, Alfonso de Albuquerque. Mango trees differ from more temperate fruit such as citrus trees with their long lifespan of possibly over a hundred years, lower environmental impacts, and great variety in their fruit.
Although the Florida state fruit is the orange, breeding mango trees in South Florida is particularly productive. In Miami, it’s commonplace to see many backyards with a mango tree pregnant with fruit from May to October. Mangoes flood the grocery stores, farmer’s markets, flea markets and yard sales. The Hayden tree was planted in Florida in 1902. Most American grocery mangoes can be traced back to this specimen which itself originated from Tamil Nadu in India. The Hayden tree was crossed with another Indian cultivar, the Brooks tree, to produce the Kent mango in 1932, and this tree still stands today. Globally, over a thousand cultivars of mangoes are grown; their names span the alphabet like a great deck of tasty jewels. Alice, Baramasia, Bombay, Carrie, Chaunsa, Doophool, Duncan, Fazli, Julie, Heidi, Kent, Madame Francis, Nam Doc Mai, Sendria, Tommy Atkins, Valencia Pride, and Zardalu are just some of the mango cultivars grown today.
Not everyone can tolerate mangoes, their leaves, or bark, as they can irritate the skin. Some wild mangoes can also have an oily, unpleasant scent, too. Mangifera belong to a large botanical family that includes poison ivy, poison oak, and the Japanese lacquer tree. All these contain a chemical, “urushiol,” that can cause dermatitis. Urushiol can be found in mango skin, so those sensitive to the poison ivy plant should take care with a whole mango. Pistachios, cashews, mombin, and the African marula also belong to the same botanical group, but these are less likely to irritate. Some Mangifera species are not well known, such as the M. altissima of the Philippines, and although its fruit are small and tasty, they have never been exported in bulk.
The Future is Mango-Golden!
Mangoes are likely to become a greater part of all our lives. Whether as fruit, ice cream, oil, chutney, as tropical spalted hardwood, or simply biochar, ancient ties with Mangifera indica are likely to become stronger. The relatively low environmental impact of this tree and its fruit make it a likely part of our future diets, just as the earlier Colin Michie planned. This marriage of new technologies and old botanical folklore will change the way we look at mangoes in our future.