Starfruit is a tropical fruit native to Asia. The cross-section of the fruit is star-shaped and hence the name. It can be yellowish or greenish with flavors ranging from bitter to sweet. It is also popularly known Carambola (Averrhoa carambola).
Nutritional Benefits Of Starfruit
Starfruit is rich in vitamin-C, which is necessary for a strong immune system and optimal bone health. It is also rich in fibers which aid in digestion and reduce cholesterol levels. Along with these, traces of B vitamins, magnesium, calcium, and potassium are found. Due to all these benefits, it is commonly consumed as a herbal remedy for various ailments in tropical countries.
However, there has been a lot of apprehension about eating this fruit, especially in patients with a kidney disorder. Various studies have been conducted and below are the conclusions.
Why Is Starfruit Bad For Kidneys?
Toxicity Due To Oxalate
Carambola belongs to the oxalidacea family of fruits. It contains oxalic acid, which combines with calcium in the kidneys of the patients who are susceptible to kidney stones. Consistent deposition of oxalic acid ultimately leads to the formation of kidney stones. In addition to this, the excess amounts of vitamin-C also result in kidney stone formation, as oxalate is a byproduct of vitamin-C breakdown. The stones are not just painful but also impair the functioning of the kidneys. Thus, research indicates that patients with pre-existing renal disorders should not consume starfruit, as it might cause acute renal injury and death in severe cases.1
Another study was conducted on patients with normal renal function. In this case, the results revealed that excessive and persistent consumption of the fruit or the juice leads to renal impairment.2 Consuming the fruit empty stomach, even in small quantities could lead to acute renal failure.3 Such cases, however, are rare.
Starfruit has neurotoxins which are capable of inducing neurological problems in patients with Chronic Kidney Disease (CKD). The neurological problems include mental confusion and persistent hiccups. The neurotoxins work by inhibiting GABA (gamma-aminobutyric acid) receptors in the brain which are responsible for cognition and coordination.4
To sum it up, patients with either normal renal function or CKD have been observed of severe side effects after consuming starfruit. While the patients with proper renal system experience a range of symptoms, the results in patients with a pre-existing kidney disorder could be fatal.
Symptoms Of Starfruit Toxicity
The symptoms show up within 1 to 5 hours after the consumption of the fruit or its juice. They include intractable hiccups, vomiting, weakness, mental confusion, epileptic seizures, coma, and in severe cases, death.
It is suggested that you eat a few pieces of starfruit and not the whole fruit at once, given you do not have any kidney ailments. Also, make sure you do not eat the fruit empty stomach. In case you have a renal disorder, consult with your doctor on the consumption and its safety.