Eating this fruit can be very dangerous…even deadly. Star fruit (also known as carambola) is a tropical fruit that traditionally comes from a tree (Averrhoa carambola) native to Sri Lanka and the Moluccas (also known as the Spice Islands), an archipelago in Indonesia. It is now grown in Florida and Hawaii, as well as in Southeast Asia and Malaysia. The name star fruit comes from the fact that when sliced, the cross section has the shape of a five-pointed star.
If you have no kidney problems, it has no effect on healthy kidneys. But if your kidney function is impaired, eating star fruit can be very dangerous, even deadly. All it takes is one small piece of the Star fruit or as little as three ounces of its juice and the ordinarily harmless star fruit transforms into poison in a matter of hours for kidney patients.
Symptoms of Star fruit intoxication that usually occur within one to five hours of eating the fruit include:
- Persistent hiccups
- Nausea
- Numbness
- Vomiting
- Agitation
- Insomnia
- Mental confusion
- Convulsions
The problem seems to be the high levels of oxalic acid (or oxalate) in this fruit that can accumulate in weakened kidneys. But since kidney patients don’t seem to have problems eating other oxalate-rich foods (such as spinach), Brazilian researchers who have been studying the reaction suggest that another, unidentified substance toxic to nerves is the real culprit.
According to the National Institute of Health, their findings suggest that star fruit juice produces acute renal injury, not only through the obstructive effect of calcium oxalate crystals, but also by inducing apoptosis of renal epithelial cells, which may be caused by the levels of oxalate in the fruit.
Food Chem Toxicol. 2008 May;46(5):1744-52. doi: 10.1016/j.fct.2008.01.016. Epub 2008 Jan 18.
