Starfruit is the fruit of the carambola tree, a species of tree native to Indonesia, India and Sri Lanka. It is found throughout Southeast Asia, Trinidad, Malaysia and parts of East Asia. It is also grown throughout the tropics. Carambola is commercially grown in the United States in south Florida and Hawaii for the fruit. It is closely related to the bilimbi.
Individuals with kidney trouble should avoid consuming the fruit, because of the presence of oxalic acid. Juice made from carambola can be even more dangerous owing to its concentration of the acid. It can cause hiccups, vomiting, nausea, and mental confusion. Fatal outcomes after ingestion of star fruits have been described in uraemic patients. The treatment is daily dialysis until the toxins are cleared from the system.
Like grapefruit, star fruit is considered to be a potent inhibitor of seven cytochrome P450 isoforms. These enzymes are significant in the first pass elimination of many medicines, and thus the consumption of star fruit or its juice in combination with certain medications can significantly increase their effective dosage within the body. Research into grapefruit juice has identified a number of common medications affected, including statins which are commonly used to treat cardiovascular illness, benzodiazepines (a tranquilizer family including diazepam) as well as other medicines. These interactions can be fatal if an unfortunate confluence of genetic, pharmacological, and lifestyle factors results in, for instance, heart failure, as could occur from the co-ingestion of star fruit or star fruit juice with atorvastatin (Lipitor).