Can chanca piedra help dissolve kidney stones?
BACKGROUND
One of our readers asked us to examine the evidence regarding a South American herb said to dissolve kidney stones. The plant grows readily in the Amazon rainforest and other tropical areas of the world. Because of its wide distribution, it has several names including Phyllanthus niruriand "chanca piedra". This translates from Spanish as "stone breaker", a name often used in marketing these herbal remedies. This links to its traditional use among Amazonian tribes to eliminate kidney stones and gallstones. The plant has a history of traditional use for numerous other conditions, including pain relief and digestive and intestinal problems.
Kidney stones form in the kidneys from deposits of various calcium salts. People can have them without realising it, but they become painful if they grow before being passed. This pain can be very severe, and can lead to more serious problems like infections and blockages. About 10-15 per cent of the population gets kidney stones, and the incidence appears to be growing in younger people.
EVIDENCE FROM STUDIES
Because of its widespread use in traditional medicine, chanca piedra has been studied extensively in research laboratories. Chemical analyses show that its extracts contain a diverse array of compounds.
Researchers in Brazil placed calcium oxalate discs in rats to test whether chanca piedra affected kidney stone formation. Rats that received chanca piedra from the beginning of the study had significantly fewer kidney stones compared with the no-treatment group. Some rats started treatment a few weeks after being given calcium oxalate. While they did develop kidney stones, they were much smaller and , therefore, easier to pass.
A few studies have been published in which patients with kidney stones were given chanca piedra extract and successfully eliminated the stones. However, all of these did not involve control groups. Only one controlled study was located. Sixty-nine patients with at least one kidney stone visible by ultrasound or X-ray were randomly assigned to take chanca piedra or placebo. After three months, no significant differences existed between the groups in the number of kidney stones passed or patients’ pain levels.
The researchers re-analysed their data and found that those who started the study with very high levels of calcium in their urine had significantly reduced levels by the end of the study. Urinary calcium levels are a risk factor for kidney stones. However, this approach to data analysis is problematic and should not be used to claim that the extract reduces urinary calcium levels. Such findings provide hypotheses that need to be tested in further research.
PROBLEMATIC ASPECTS
Adverse effects have not been reported for chanca piedra. However, lab and animal studies have found that compounds purified from the extracts can lower blood pressure and blood glucose levels. These findings have not been demonstrated in humans, but they do suggest that people taking medication for blood pressure or diabetes should not take chanca piedra until after discussing this with their doctor or pharmacist.
RECOMMENDATIONS
Kidney stones can be extremely painful and are becoming more prevalent. Most smaller stones will be passed spontaneously, helped by greatly increasing water intake. For people who regularly form kidney stones, various dietary and medical interventions have been suggested with varying degrees of effectiveness.
The evidence that chanca piedra may help during the acute, painful stage of kidney stones is very weak. However, for someone who regularly produces kidney stones, the extract might help prevent or slow their development. A trial period might be helpful, although further studies are needed before great confidence can be placed in chanca piedra.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, DCU.
