Diets high in calcium, potassium may prevent recurrent symptomatic kidney stones: Study

Renal stones are associated with cardiovascular disease, osteoporosis, and chronic kidney disease in addition to being excruciatingly painful. If you’ve already had a kidney stone, your chance of getting another one within five years rises by 30%.

The Mayo Clinic Proceedings journal reported the study’s findings. Dietary modifications are frequently advised to stop kidney stones from symptomatically returning. However, there is no evidence on dietary adjustments for people who only get kidney stones once vs people who do so often.

Researchers at the Mayo Clinic created a prospective study to look into the effects of dietary changes. Their research demonstrates that adding foods high in calcium and potassium to the diet can help prevent kidney stones from developing again.

Dietary variables were based on a questionnaire given to 411 patients who had first-time symptoms of kidney stones and a control group of 384 individuals; both groups were seen between 2009 and 2018 at Mayo Clinics in Rochester and Florida. The results of the study indicate that lower dietary intakes of calcium and potassium, as well as fluids, caffeine, and phytate, are linked to greater probabilities of developing a kidney stone for the first time.

Within a median of 4.1 years of follow-up among the patients who had stones for the first time, 73 of them developed stones again. Lower dietary calcium and potassium levels were found to be predictive of recurrence in further study.

“These dietary findings may have particular importance because recommendations for preventing kidney stones have been based primarily on dietary factors associated with first-time rather than recurrent stone formation,” says Andrew Rule, M.D., a Mayo Clinic nephrologist and senior author of the study.

“Patients may not be likely to adjust their diet to prevent an incidence of kidney stones, but they are more likely to do so if it can help prevent a recurrence.”

The study indicates that ingestion of phytate, caffeine, and fewer than 3,400 millilitres of fluid per day (approximately nine 12-ounce glasses) are all related to the development of new stones. Drinking water each day also entails eating things like fruits and vegetables.

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Reduced fluid and caffeine intake can cause low urine volume and higher urine concentration, which can aid in the development of stones. Whole grains, nuts, and other foods include phytate, an antioxidant molecule that can enhance urine calcium excretion and calcium absorption.

“Changing your diet to prevent kidney stones can be very difficult,” says Dr. Rule. “Thus, knowing the dietary factors that are most important for preventing kidney stone recurrence can help patients and providers know what to prioritize.”

Low dietary calcium and potassium was a more important predictor than fluid intake of recurrent kidney stone formation, says Api Chewcharat, M.D., the article’s first author and a postdoctoral research fellow at Mayo Clinic at the time of the study. “This is not to say high fluid intake is not important. We just did not find benefits of increasing fluid intake among those patients with a history of kidney stone formation.”

The study concludes that diets with daily intake of 1,200 milligrams of calcium may help prevent first-time and recurrent kidney stones. That daily intake is in line with the Department of Agriculture’s daily recommended nutrition.

While higher potassium intake also is recommended, the USDA does not make a recommendation for daily potassium intake. The study also doesn’t recommend an intake level.

Dr. Chewcharat says the takeaway is that patients should add more fruits and vegetables that are high in calcium and potassium to their diets. Fruits that are high in potassium include bananas, oranges, grapefruits, cantaloupes, honeydew melons and apricots. Vegetables include potatoes, mushrooms, peas, cucumbers and zucchini.

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