Averrhoa carambola Linn: Is It Really a Toxic Fruit?

Averrhoa carambola, or star fruit, is a tropical fruit found throughout Southeast Asia and is usually consumed fresh or as fruit juice. The fruit is a very good source of natural antioxidants, phenolic compounds such as gallic acid in gallotannin form, catechins, and epicatechins. Various medicinal uses for carambola are found in folk medicine. In India, the ripe fruit is administered to halt hemorrhaging, and the dried fruit or the juice may be taken to counteract fevers; star fruit jam is said to allay biliousness and diarrhea and to relieve a hangover from excessive indulgence in alcohol. In Brazil, carambola is recommended as a diuretic and for the treatment of eczema. Because of the high concentrations of oxalic acid present in carambola, the excessive consumption of its fruit by dialysis patients can cause neurotoxicity and impair cognitive abilities and, if there is no immediate relief, even death. In addition to oxalic acid which is responsible for nephrotoxic phenomena in subjects with impaired renal function, caramboxin has recently been identified as a substance that acts on the central nervous system causing symptoms such as sobbing, confusion, and in more serious conditions, convulsions and death.