Can mangosteen act as a source of antioxidants?
BACKGROUND
Mangosteen is a tropical tree from Southeast Asia. The name comes from its scientific name, Garcinia mangostana, and should not be confused with other Garcinia supplements or mango fruit. Mangosteen fruit has been called the “Queen of Fruit” because it is held by many to be the best-tasting tropical fruit. Another story claims that it got this name because mangosteen was believed to be Queen Victoria’s favourite fruit.
The mangosteen tree is very difficult to grow outside of the tropics, which has kept it out of Western markets until very recently. Soon after importation restrictions were lifted, mangosteen fruit and juice became very popular for their health benefits. Mangosteen juice became one of the first “superfruits”, a marketing term devised in the US to promote new, exotic fruit juices alleged to have various health benefits.
Different parts of the mangosteen tree have been used in Asia for centuries to treat a wide variety of medical conditions. The fruit hull has been powdered and used to treat diarrhoea, while the leaves and bark were used to reduce inflammation. Lotions were made from various parts of the tree to treat wounds and infections. In the Caribbean, a tea made from the fruit was used in the belief that it gave people more energy.
EVIDENCE FROM STUDIES
Mangosteen has been the subject of much recent research because of the wide range of traditional uses. A group of compounds called “xanthones” have been identified. These are found in very few plant species and have aroused much interest among researchers. Chemically, xanthones are similar in structure to other plant antioxidants. To date, about 60 different compounds have been identified. Many of these have been tested in laboratory experiments and found to be good antioxidants.
Normal activity in the body produces various waste products which need to be eliminated by antioxidants. Some of these are made in the body, and many others are provided by a healthy diet. The risk of some chronic illnesses increases when people’s diets are low in antioxidants. Studies have shown that individual xanthones, mangosteen extracts and commercial mangosteen juice are high in antioxidants.
Other laboratory tests have demonstrated that individual xanthones have a variety of beneficial effects on tissues and biochemical processes. However, no clinical studies could be found where any of these compounds, or any mangosteen products, were tested on humans.
Mangosteen juice and extracts also contain lycopene, an antioxidant associated with reduced cancer risk. However, that connection has only appeared in epidemiological studies of people’s eating habits.
PROBLEMATIC ASPECTS
No adverse effects have been reported with mangosteen. Animals have been given very large doses of mangosteen extracts without evidence of harm. However, controlled investigations of the safety of mangosteen products have not been published.
RECOMMENDATIONS
Mangosteen fruit and juice have become popular. As a way to include an adequate amount of fruits and vegetables in the diet, mangosteen can be recommended. However, some products are advertised as having all sorts of health benefits. Such claims are usually linked to traditional uses of the fruit, which do not necessarily correspond to the products on the market today. While many interesting compounds have been isolated from mangosteen, none of these have undergone the necessary trials to establish if they are effective or safe. Currently, no reliable evidence supports any specific health claims for mangosteen. Until controlled studies are available, enjoy the fruit and avoid the hype.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University
