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Stones under control

Shatterstone tea (chá de quebra-pedra) prevents crystals of calcium oxalate from grouping and forming kidney stones

eduardo cesarOver the last few years, various scientific researches have practically proven the benefit of using the shatterstone tea (chá de quebra-pedra) to combat kidney stones. Nonetheless, what was missing was to discover the mechanism of the action of the infusions done with the leaves and seeds of the vegetal species Phyllantus niruri, the scientific name of the plant. Recent studies conducted by researchers at the Federal University of São Paulo (Unifesp) have taken a significant step in this direction. Contrary to what its name might lead one to conclude, shatterstone tea doesn’t break anything. It does not make a kidney stone break into smaller pieces, as many people believe. Its positive effect is a little more subtle, more preventative than curative, but no less efficient.

The tea impedes the clumping together of crystals of calcium oxalate, the chemical compound most common in kidney stones. Under its action, the crystals end up not adhering one to another, thus avoiding the formation of kidney stones of greater dimension, those that provoke pain in the region of the kidney and are difficult to be expelled without the help of some medicine or treatment.

In practice, the infusions with Phyllantus stop the process of the growth of the stones already in existence and avoid the formation of new stones. Only because of this property, the consumption of tea, under medical supervision, would be recommended. However, the research indicates that the drink can give rise to a second relief to the sufferers of kidney stones, around 10% of the general population: the shatterstone tea is capable of relaxing the urinary system, which makes the task of eliminating the stones less painful. “In the worst of hypothesis, shatterstone tea is just as efficient as the conventional medicines used in the treatment of kidney stones”, compares the nephrologist Nestor Schor of Unifesp.

“With the advantage of being a cheaper product and proven to be non-toxic.” Schor is the coordinator of a thematic project through FAPESP on acute renal inefficiency and other questions related to kidneys, such as the study of the formation of the stones in the organism and the mechanism of the aqueous extract – the tea itself – of the Phyllantus plant. In another line of study on the same theme, researchers have discovered that a urine protein, the retinal binding protein (RBP), can be a precocious indicator of future kidney problems in patients who suffer heart transplants.

The presence of kidney stones is an ancient problem for the human species. The analysis of Egyptian mummies show that kidney stones were already a torment for the life of that people, at least seven thousand years ago. There is nothing specific that can be pointed to as the major factorthat starts up the formation of stones in the majority of people, in spite of the incidence of stones showing a growing curve in recent history. Genetic and hereditary factors, metabolic problems, infections of the urinary system and even personal inactivity could be associated with the occurrence of the problem.

The idea that diets extremely rich in calcium necessarily bring on kidney stones has no scientific backing. Unless there is a genetic-metabolic predisposition, a person will not develop kidney stones because of the consumption of milk and its derivatives, food with a high concentration of this chemical element. In concrete terms, medical statistics show that the current levels of re-incidence of kidney stones are high. “Half of the people who have had kidney stones have the problem again within a period of a year and 70% within two years”, says Mirian Boim, a physiopathologist at Unifesp who has been studying the action of shatterstone (Phyllantus) for some fifteen years.

Anti-adherent action
The mechanism of the tea’s action in combating the formation of stones in the kidneys has still not been totally unveiled, but the researchers have made some progress. For example, they discovered that the infusion of Phyllantus decreases the adhesion of calcium oxalate crystals on the walls (epithelium) of the renal tubule, a fine tube that makes up part of each active excretion unit of the kidney. What has this got to do with the origin of the stones? For the formation of stones to occur in the kidneys, it is essential that there can be the adhesion of these mini particles on the walls of the tubule.

“If this doesn’t happen, the oxalate crystals remain suspended and will be eliminated with the urine”, says Mirian. After sticking to the walls of the tubule, the particles of calcium oxalate are absorbed by the renal cells, in a process called endocytosis. When they are large, with size greater than half a millimeter, the crystals can bring on the death of the cells. But the smaller ones spend some time in the interior of the cells and are liberated once again into the renal tubule. The problem is that, after the inter cellular movement, the crystals return more robust, having incorporated proteins, and clumped together which increases their dimension.

Through the clues gathered during their experiments, the researchers have formulated a hypothesis to explain why the shatterstone tea avoids the adhesion of the particles of calcium oxalate. In a simplified form, one can say that the crystals attach themselves to the cellular wall because there is an electrical attractive force between both. The crystals are positively charged, and the cellular wall is negatively charged. “The Phyllantus seems to change the polarity of the crystals’ charge, thus inhibiting its adhesion to the epithelium and decreasing the process of endocytosis”, explains Mirian. To make the formation of the stones even more difficult, the teas also promotes an alteration in thestructure of the type of calcium oxalate crystal that is more harmful to the organism, the so called monohydrates, that stick more easily onto the cell wall. The tea transforms them into dehydrated crystals, whose degree of adherence is much smaller.

To avoid the entrance of particles of calcium oxalate in cellular walls seems to be a priority not only of the shatterstone tea, but of the plant itself. Alerted by an Australian colleague, who had observed the presence of the crystals on the leaves of similar vegetal species, the physiopathologist perceived the same phenomenon in Phyllantus niruri (shatterstone). In an apparent self defense mechanism, which regulates the level of calcium in its cells, the plant inhibits the entrance of the crystals, which then provokes the accumulation of the particles on the external part, the leaves. With the help of an electronic microscope, Mirian easily identified the crystals on the leaves of the Phyllantus niruri (shatterstone). What everything seems to indicate is that this natural mechanism of regulating the entrance of the calcium, remains active in the aqueous extract of the plant and is passed on to whoever drinks the tea.

Golf ball
Kidney stones can be the size of a grain of sand or of a pearl. In extreme cases they can reach the size of a golf ball. They can be smooth or can exhibit scars. In color they are yellow, reddish or brown. In 80% of the cases they are made up of calcium oxalate, but l there are also kidney stones made from calcium phosphate, uric acid and other materials, or even a combination of various chemical elements. In simple cases, the doctors normally request that those with kidney stones drink a lot of water, which facilitates movement and the consequent elimination of the stone, along with an analgesic or anti-inflammatory so as to diminish the pain. In extreme situations, in which the stone is larger and the suffering is greater, the patient is interned in a hospital. In the past, the procedure – standard in these occasions – was surgery for the removal of the stone. Today, in some cases alternative methods, non-surgical, such as the use of equipment that creates shock waves that break up the stones into smallerpieces, can be employed.

All of the scientific evidence, the fruit of research such as the use of tea in rats, human beings and tests conducted in vitro, indicate that the drink can be an alternative to some of these procedures. After all , the aqueous extract of Phyllantus truly prevents the formation of new stones and can help in the elimination of those already existing. This, however, does not mean that the Unifesp researchers recommend its indiscriminate use. There is still the necessity for prolonged studies that will follow the action of the tea on its users for a period of six months.

Up until now, the maximum time of accompanying patients has been restricted to three months. Even the doctors themselves don’t know what is the ideal dose of tea that should be consumed by those suffering from kidney stones. Besides these scientific hurdles, there are some practical ones that discourage self-medication. There is not in the market a commercial tea of quality produces with the vegetal species and some people can confuse the Phyllantus niruri with other plants and end up taking an incorrect fusion. “The tea works but caution is needed by the person who drinks it”, says Schor.

Relief for those receiving a transplant
Cyclosporine, the main drug used in combating the rejection of transplanted organs, increases the survival of the patients but often causes an undesirable side effect. Its continued use, and in high doses, provokes kidney damage, and could lead to the complete failure of this organ, a health problem that increases the death risk in this type of illness. The team of MD Alvaro Pacheco e Silva Filho, of Unifesp, have discovered a form of precociously making a diagnosis of this kidney aggression, when the kidney failure is still in its initial phase and perhaps can be controlled.

The researchers realized that heart transplant patients who show high concentrations of a known protein found in the urine, the retinol binding protein (RBP), have a higher chance of developing chronic kidney failure. Even when all of the other clinical parameters of the patient reveal themselves to be clearly satisfactory, such as the level of creatinine (classically a protein measured to infer the degree of working of the kidney), a simple increase in the quantity of RBP in the urine indicates that the damage to the kidneys is already underway. “In this case, we are speaking of transplanted patients who, up until now, were judged to be perfectly healthy” comments Silva Filho. “Patients whom any doctor would have examined and declared to be doing very well.”

The doctor has managed to establish a relationship between the levels of RBP and kidney problems after having carried out measurements on heart transplants cases in excellent clinical condition. Among those who showed rates of the protein higher than 0.4 mg/liter of urine, 38% developed chronic kidney failure, leading towards the loss of one or both kidneys. The patients with lower levels than this index, did not have a single case of chronic kidney failure registered. “In not one of these transplants was there the loss of a kidney.”

Seen now as a marker of the level of renal toxicity by cyclosporine, the level of RBP is a new weapon in the fight to control the side effects of cyclosporine. It is an arduous battle. In order to decrease the negative action of the anti-rejection drug, doctors are accustomed to reducing the dosage of the medicine or using new compounds apparently less toxic, such as azathioprine or the mycophenolate mophetil. “With these procedures, we have already managed to lower the level of RBP in some patients, but we still don’t know for certain that the kidney cells have not been suffering”, ponders Silva Filho. No matter what, the discovery of the marker provides an anticipated warning of the problem. “We have found a new use for an old test”, comments Silva Filho. 

The Project
Cellular and Molecular Aspects of Acute Renal Insufficiency (nº 97/01015-7); Modality Thematic project; Coordinator Nestor Schor – Unifesp; Investment R$ 2,469,886.53