People Who Eat Higher Amounts of Potassium and Calcium May Reduce Their Risk of Recurrent Kidney Stones
Lower levels of fluid and caffeine intake associated with higher odds of developing kidney stones.
People who eat a diet low in calcium and potassium may be more likely to develop first time and recurrent kidney stones, according to a new Mayo Clinic study. Lower dietary caffeine, phytate, and fluid intake were also associated with higher odds of incident symptomatic kidney stones, according to the results, published on August 1 in Mayo Clinic Proceedings.
"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," said senior author Andrew Rule, MD, a nephrologist at Mayo Clinic in Rochester, Minnesota in a release. "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 recurrence."
About 1 in 10 People Will Get Kidney Stones During Their Lifetime
Symptomatic kidney stones can cause severe pain, the need for expensive medical care, and surgical interventions, according to the authors. Over a half-million people go the emergency room for kidney stones each year, and it’s estimated that about 1 out of every 10 people will have a kidney stone at some point in their lives, according to the National Kidney Foundation. People who have experienced a kidney stone have about a 30 percent chance of having another one within five years.
A kidney stone is a hard object that is created from chemicals in urine. When there is too much waste and too little liquid in the urine, crystals begin to form and can join with other elements to form a solid that can grow into a kidney stone.
Symptoms can include sharp pains in your back, side, lower abdomen, or groin, and pink, red, or brown blood in your urine. Some people may feel a constant need to urinate, pain while urinating, inability to urinate or only able to urinate a small amount, or cloudy or bad-smelling urine, according to the National Institute of Diabetes and Digestive and Kidney Diseases. If a person experiences any of these symptoms, they should see a healthcare provider right away.
Researchers Examine Dietary Patterns for Both Incident and Recurrent Kidney Stones
Once a person has had an occurrence of kidney stones, it’s common practice for doctors to recommend changes in the diet, such as eating fruits and vegetables with high water content. However, there isn’t much existing research that looks at dietary differences in people with one incident of kidney stones versus people who have recurrent incidents, according to the authors.
To investigate the impact of diet in both groups, researchers recruited a total of 795 people who visited the Mayo Clinic in Rochester and in Florida between 2009 and 2018; 411 of the subjects had experienced first-time symptomatic kidney stones, and the control group included 384 people who had not had kidney stones.
Dietary factors were assessed via a questionnaire that gathered information from the participants on 155 different food and beverage items. Participants were then followed for a median of 4.1 years.
Calcium, Potassium, Caffeine, Phytate, and Plenty of Fluids May Help Prevent Kidney Stones
Investigators analyzed the dietary patterns of the different groups and found that consuming lower levels of dietary calcium and potassium as well as lower intake of fluids, caffeine, and phytate, were all associated with higher odds of experiencing a first-time symptomatic kidney stone.
The researchers considered “lower fluid intake” to be less than 108 ounces a day (nine 12-ounce glasses), which included water found in fruits and vegetables. It’s estimated that about most people get about 20 percent of their fluids from the foods they eat, according to the American Academy of Nutrition and Dietetics.
Less caffeine was associated with greater risk of stone formation, a link that’s been found in previous research. A study published in October 2021 in the American Journal of Kidney Diseases found that 1 to 1.5 cups a coffee a day reduced the risk of kidney stones by 40 percent.
Low phytate levels were also found in people who developed incident kidney stones. Phytate is an antioxidant compound found in whole grains, nuts and other foods, and is believed to help with calcium absorption and urinary calcium excretion, according to the authors.
During the follow up, 73 people experienced recurrent kidney stones. Further analysis revealed that lower levels of dietary calcium and potassium were the best predictors of recurrence of stone formation. "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,” said lead author Api Chewcharat, MD, an internal medicine resident at Mount Auburn Hospital in Cambridge, Massachusetts, in the release.
Authors Recommend Consuming Plenty of Vegetables and Fruit and 1200 mg of Calcium Per Day
On the basis of these findings, the authors recommend getting 1200 milligrams (mg) of calcium a day to help prevent first-time and recurrent kidney stones, which is in line with the National Institute of Health's recommendation of 1000 to 1200 mg per day for adults (depending on age and gender). Dairy products, tofu, and leafy greens are all good sources of the mineral.
The authors don’t recommend a specific goal for potassium (neither does the U.S. Department of Agriculture), but suggest consuming a diet high in potassium, especially vegetables and fruit.