A diet high in fruits, vegetables, legumes and nuts, moderate in low-fat dairy products, and low in animal proteins, refined grains and sweets may reduce risk for developing kidney stones, according to a new study published in the National Kidney Foundation's American Journal of Kidney Diseases. March is National Kidney Month and the National Kidney Foundation (NKF) encourages people to learn about the kidneys and associated conditions, including kidney stones.
Researchers found that compared with following a low-oxalate diet - the frequently prescribed diet for kidney stone prevention and treatment - a Dietary Approaches to Stop Hypertension (DASH) - style diet may be more effective at reducing urinary risk markers for calcium oxalate kidney stone formation, the most common type of kidney stone. Oxalate is naturally found in high levels in many foods with other nutritional value including: beets, navy beans, bulgur, kale, almonds, sweet potatoes, rice bran, rhubarb and spinach.
According to the National Kidney Foundation, most kidney stones are formed when oxalate binds to calcium while urine is produced by the kidneys. Eating and drinking calcium and oxalate-rich foods together during a meal may be a better approach than limiting oxalate entirely. This is because oxalate and calcium are more likely to bind to one another in the stomach and intestines before the kidneys begin processing, making it less likely that kidney stones will form.
"Previous studies have recommended that those with kidney stones follow a low-oxalate diet to reduce one's chances of forming another stone. However, many high oxalate foods are healthful and a low-oxalate diet can be very restrictive. The DASH diet reflects a more balanced diet and as a result may be easier and more realistic to follow long-term," said Dr. Kerry Willis, Senior Vice President for Scientific Activities at the National Kidney Foundation.
Researchers led by Nazanin Noori, MD, PhD at The Hospital for Sick Children in Toronto examined the dietary interventions in 41 participants over the course of eight weeks. On average, study participants who followed the DASH diet decreased their risk for stone formation by 35%, while those who followed the low oxalate diet reduced their risk for stone formation by 14%. The urinary risk markers for kidney stones included calcium, oxalate, citrate, sodium, potassium, magnesium, uric acid, pH and urinary supersaturation of calcium oxalate.
According to Dr. Noori, "Most people do not eat single, isolated nutrients, such as oxalate, but rather meals consisting of a variety of foods. So a practical diet plan for kidney stone prevention should be based on the cumulative effects of foods and the impact overall dietary patterns have on risk for stone formation rather than single nutrients."
4 Tips from the National Kidney Foundation to Reduce Your Risk of Forming Kidney Stones During March, National Kidney Month
- Drink fluids! Ideally, 2-3 liters daily.
- Water is best. Water is the best fluid to drink. Another option is sugar-free fresh lemon or lime juice mixed with water.
- Eat fruits and veggies. In general, eating a diet high in fruits and vegetables, moderate in low fat dairy and low in salt and animal protein might prevent kidney stone formation. Most Americans eat more than the recommended amounts of animal protein and salt.
- Stick to a treatment plan. After a kidney stone, work with a doctor to create an individual treatment plan that considers fluid intake, diet and sometimes medication.