A Fruit Extract to Dissolve Kidney Stones
Researchers at the University of Houston have found evidence that an extract of the rind of the Indian fruit Garcinia cambogia is capable of dissolving calcium oxalate crystals, the most common component of human kidney stones. This finding could lead to the first advance in the treatment of calcium oxalate stones in 30 years.
Jeffrey Rimer, associate professor of chemical engineering at the University of Houston, was lead author of the study, published August 8th 2016 in the online edition of Nature. The work offers the first evidence that the compound hydroxycitrate (HCA), an active ingredient extracted from the Garcinia cambogia fruit, is an effective inhibitor of calcium oxalate crystal growth that, under certain conditions, is actually able to dissolve these crystals.
According to a release from the university, Rimer said the findings are the result of a combination of experimental studies, computational studies and human studies..
The release explains that kidney stones are small, hard mineral deposits that form inside the kidneys, affecting up to 12 percent of men and seven percent of women. High blood pressure, diabetes and obesity can increase the risk, and the reported incidence is on the rise.
Preventive treatment has not changed much over the last three decades. Doctors tell patients who are at risk of developing stones to drink lots of water and avoid foods rich in oxalate, such as rhubarb, okra, spinach and almonds. They often recommend taking citrate (CA), in the form of potassium citrate, a supplement that can slow crystal growth, but some people are unable to tolerate the side effects.
The project grew out of preliminary work done by collaborator John Asplin, a nephrologist at Litholink Corporation, who suggested HCA as a possible treatment. HCA is chemically similar to CA and is also available as a dietary supplement.
“HCA shows promise as a potential therapy to prevent kidney stones,” the researchers wrote. “HCA may be preferred as a therapy over CA (potassium citrate).”
In addition to Rimer and Asplin, authors on the paper include Giannis Mpourmpakis and his graduate student, Michael G. Taylor, of the University of Pittsburgh; Ignacio Granja of Litholink Corporation, and Jihae Chung, a UH graduate student working in Rimer’s lab.
The head-to-head studies of CA and HCA determined that while both compounds inhibit the growth of calcium oxalate crystals, HCA was more potent and displayed unique qualities that are advantageous for the development of new therapies.
The team of researchers then used atomic force microscopy, or AFM, to study interactions between the crystals, CA and HCA under realistic growth conditions. According to Rimer, the technique allowed them to record crystal growth in real time with near-molecular resolution.