Star Fruit/ Carambola: harmful for kidney

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Offline Nazneen

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Star Fruit/ Carambola: harmful for kidney
« on: April 15, 2019, 05:25:16 PM »
Star fruit — or carambola — is a sweet and sour fruit that has the shape of a five-point star. The skin is edible and the flesh has a mild, sour flavor that makes it popular in a number of dishes. The star fruit is yellow or green in color. It comes in two main types: a smaller, sour variety and a larger, sweeter one. It is originally from Asia. The fruit gets its name because it is shaped like a star when sliced.

The star fruit is a decent source of several nutrients — especially fiber and vitamin C.

This is the nutrient content of a single, medium-sized (91-gram) star fruit :

    Fiber: 3 grams
    Protein: 1 gram
    Vitamin C: 52%
    Vitamin B5: 4%
    Folate: 3%
    Copper: 6%
    Potassium: 3%
    Magnesium: 2%

Side Effects:

Studies show that eating starfruit can have a harmful (toxic) effect for people who have kidney disease. Star fruit may cause adverse effects in some people, mainly due to its high oxalate content. The substances found in starfruit can affect the brain and cause neurological disorders. This toxic substance is called a neurotoxin. People with healthy, normal kidneys can process and pass this toxin out from their body. However, for those with kidney disease, this is not possible. The toxin stays in the body and causes serious illness.

The symptoms of starfruit poisoning include:

    Hiccups
    Mental confusion
    Seizures
    Death (in serious cases)

Mechanism of toxicity:

Hiccups are a common and often harmless myoclonus of the diaphragm. However, in patients with renal disease and recent star fruit ingestion, this spasm can be a sign of toxicity and occurs in up to 94% of patients who present with intoxication. Toxicity can also result in vomiting, weakness, confusion, convulsions, and death.
 
Star fruit contains two molecules that are responsible for kidney damage and neurotoxicity: oxalate and the recently discovered caramboxin.
 
Oxalic acid’s effects on kidneys are well-known and well defined, partly due to its culpability in ethylene glycol toxicity and death. Oxalate crystallizes and forms obstructive deposits that cause direct tissue damage in the form of both apoptosis and acute tubular necrosis. Neurotoxic effects are due to the more elusive compound of interest, caramboxin. Garcia-Cairasco and colleagues conducted a bioguided isolation of the toxin and termed the new, “phenylalanine-like” molecule with 2 carboxylic acids. They also discovered its strong N-methyl-D-aspartate glutamatergic receptor agonist activity and justified the hyperexcitability of neurons in patients who experience this toxicity.

So, patient with kidney disease should avoid star fruit and those without renal disease should take caution to not consume large amounts of the fruit or its products and ensure that ingestion does not occur on an empty stomach.

Nazneen Ahmeda Sultana
Lecturer, Department of Pharmacy
Faculty of Allied Health Science
Daffodil International University
E-mail:nazneen.ph@diu.edu.bd