Carambola is rich in antioxidants and vitamin C and low in sugar, sodium and acid. It is also a potent source of both primary and secondary polyphenolic antioxidants. carambola has both antioxidant and antimicrobial activities: scavenging of NO by the fruit extract is dependent on concentration and stage of ripening. Extracts showed antimicrobial activity against E. coli, Salmonella typhi, Staphylococcus aureus and Bacillus cereus.
Carambola is a fairly complex fruit with many benefits, but like strawberries, a small percentage of the human population should be cautious of the fruit for health reasons. Carambola contains oxalic acid, which can be harmful to individuals suffering from kidney failure, kidney stones, or those under kidney dialysis treatment. Consumption by those with kidney failure can produce hiccups, vomiting, nausea, and mental confusion. Fatal outcomes have been documented in some patients.
Like the grapefruit, carambola 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 carambola 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, and benzodiazepines (a tranquilizer family including diazepam).