Mayo Clinic study reveals a nutritional trick to help prevent kidney stones

Kidney stones illustration. Mayo Clinic researchers have found that enriching diets with foods rich in calcium and potassium may prevent frequent symptomatic kidney stones.

Diets rich in calcium and potassium may help prevent kidney stones from recurring

Kidney stones can not only cause severe pain, but they are also linked to chronic kidney disease, osteoporosis, and cardiovascular disease. If you’ve had a kidney stone once, you have a 30% chance of developing another kidney stone within five years.

Usually, doctors prescribe changes in the diet to prevent the appearance of kidney stones with frequent symptoms. Unfortunately, there is little research available regarding dietary changes for those who have had a single episode of kidney stone formation versus those who have had frequent incidents.

Kidney stones are a hard, pebble-like substance that can form in one or both kidneys when your urine contains high levels of certain minerals.

Therefore, Mayo Clinic researchers designed a prospective study to investigate the effect of dietary changes. According to their findings, enriching diets with foods rich in calcium and potassium may prevent kidney stones with frequent symptoms.

The study involved 411 patients who developed symptomatic kidney stones for the first time and a control group of 384 people. Dietary factors were based on a survey of participants, all seen at the Mayo Clinic in Rochester and the Mayo Clinic in Florida between 2009 and 2018. The results, to be published today (August 1) at Mayo Clinic proceduresshowed that low calcium and potassium in the diet, as well as low fluid, caffeine, and phytate intake, are associated with higher odds of developing first-appearing kidney stones.

Among the patients who underwent stone formation for the first time, 73 patients experienced a recurrence of stones during a median of 4.1 years of follow-up. Additional analysis revealed that low levels of dietary calcium and potassium are predictive of recurrence.

“These dietary findings may be of particular importance because recommendations for kidney stone prevention have been based primarily on dietary factors associated with first-time stone formation rather than recurrence,” says Andrew Roll, MD, a Mayo Clinic nephrologist and senior author of the study. “Patients may not be likely to adjust their diet to prevent kidney stones, but they are more likely to do so if it can help prevent their recurrence.”

The study found that a fluid intake of less than 3,400 milliliters per day, or about nine 12-ounce cups, was associated with first-time stone formation, along with caffeine and phytate intake. Your daily fluid intake includes eating foods such as fruits and vegetables.

Drink plenty of water if you have a kidney stone unless your health care professional directs you otherwise.

Decreased fluid and caffeine intake can lead to decreased urine volume and increased urine concentration, which contributes to stone formation. Phytate is an antioxidant compound found in whole grains, nuts, and other foods that can increase calcium absorption and excretion of calcium in the urine.

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

Api Chewcharat, MD, first author of the article and a Mayo Clinic postdoctoral research fellow at the time of the study, says that low dietary calcium and potassium was a more important predictor of fluid intake than frequent kidney stone formation. This does not mean that a large fluid intake is not important. We did not find benefits for increased fluid intake among those patients with a history of kidney stone formation.”

The study concluded that diets containing 1,200 milligrams of calcium per day may help prevent first-time kidney stones and their recurrence. This daily intake is in line with the USDA’s recommended daily nutrition.

While higher potassium intakes are also recommended, the USDA does not recommend daily potassium intake. The study also does not recommend an intake level.

The takeaway, Dr. Chewcharat says, 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, grapefruit, cantaloupe, watermelon, and apricots. Vegetables include potatoes, mushrooms, peas, cucumbers, and zucchini.

Reference: “Dietary Risk Factors for Occurring and Recurrent Kidney Stones” August 1, 2022, Available here. Mayo Clinic procedures.
DOI: 10.1016 / j.mayocp.2022.04.016

Co-authors with Dr. Rule and Chewcharat are Charat Thongprayoon, MD; Lisa Vaughan; Ramila Mehta; Philip Schulte, Ph.D.; Helen O’Connor and John Lesky, MD — both of the Mayo Clinic — and Erin Taylor, MD, of the VA Maine Healthcare System. Dr. Schulte reports the personal charges from OxThera Inc. outside the scope of work in this study. Dr. Lieske reports on grants and/or other fees from pharmaceutical and related companies identified in the article—all outside of this study and all paid to Mayo Clinic. The report’s other authors have no competing interests.

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