Fruit extract dissolves kidney stones

A compound from fruit has been found to dissolve painful kidney stones.
12 August 2016


A cartoon illustration of a right and left kidney


Researchers have found a new way to treat painful kidney stones with the help of a citrus fruit's extract which stops the crystals from growing...

About 20 percent of people in the UK develop a kidney stone at some time in their lives, most commonly between the ages of 20 and 40.

Kidney stones are hard chunks of mineral crystals and acids that form inside the kidneys and cause extreme pain - some have even linked it to the childbirth pain. However, in the last 30 years, there has been very little improvement in treating these stones. People who are at risk of developing stones are advised to drink lots of water and avoid certain types of food, or to take citric acid (CA) supplements that can slow crystals growth, however some people are unable to tolerate its side effects.

Now, researchers from University of Houston have come up with the citrus fruit extract hydroxycitrate (HCA) which is capable of dissolving calcium oxalate crystals, a major component of the kidney stones.  

HCA is chemically similar to the citrate CA supplement and while both inhibit the growth of the calcium oxalate crystals, HCA was found to be more potent, so preferable for the further development of new therapies.

To find out how these two citrate molecules attack crystals, they applied both drugs, CA and HCA to the crystal's solid mass, under physiological conditions and monitored their growth. Their results indicate that, when exposed to specific concentrations of HCA, crystals extensively shrink and eventually dissolve.

To explain why this happened, the researchers explored how HCA and CA bind to the kidney stone's crystals. They discovered that HCA - but not CA, has a stronger attachment to the crystal's surface, which breaks up calcium oxalate and leads to crystal dissolution.

The next step was testing HCA in humans. Seven people took the drug for a few days and their urine was monitored. The HCA was found excreted in the urine, meaning the molecule did indeed travel through the kidneys, showing promise to function as an effective therapy.

 Still, this molecule has a long way to go before it can be released in the market.  Some of the hurdles that it needs to overcome include testing the long-term safety, dosage and tolerability.


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