Managing Calcium Intake Key to Reducing Kidney Stone Risk

Most kidney stones are primarily composed of calcium, with approximately 85% containing the mineral. Individuals prone to kidney stones often exhibit high levels of calcium in their urine. However, this is not necessarily a reason to eliminate calcium supplements from one's diet. Proper calcium intake, along with other dietary considerations, can positively impact kidney health.

How Calcium and Oxalate Form Stones

After food is processed by the body, waste products are expelled through urine. When insufficient water passes through the kidneys, these waste particles can adhere and crystallize into stones. The most prevalent type of kidney stone forms when calcium binds with oxalate, an antinutrient found in plant foods. This bonding occurs when levels of calcium or oxalate in the urine are excessively high.

Individuals with idiopathic hypercalciuria experience high urine calcium levels despite normal calcium intake. Those with hyperparathyroidism face increased blood calcium levels, elevating their risk for kidney stones. Dr. Amy Yau, a nephrologist at The Ohio State University Wexner Medical Center, notes that for individuals without hypercalciuria, excessive calcium consumption might raise stone risk. Nonetheless, factors such as inadequate water consumption or high salt intake are more critical in influencing this risk.

Excess Calcium Isn't the Main Cause of Kidney Stones

Some individuals might require calcium supplements for bone health. Surpassing the recommended daily intake of 1,000-1,300 milligrams from both food and supplements can lead to excess calcium being excreted in urine. However, Melanie Betz, a dietitian and author of The Kidney Dietitian blog, stresses that excess calcium is not the primary cause of kidney stones. In fact, those with calcium oxalate stones should focus on maintaining adequate calcium intake.

Getting Enough Calcium Reduces Kidney Stone Risk

Research indicates that low calcium diets correlate with a heightened risk of kidney stone formation. Consuming sufficient calcium aids in binding oxalates from high-oxalate foods like beets and almonds, allowing them to be excreted in stool instead of urine, where they can form stones.

A High Sodium Diet Is More Likely to Cause Stones

Dr. Yau recommends reducing salt intake over calcium when addressing calcium-oxalate stones. High sodium consumption results in both calcium and sodium being expelled in urine, increasing crystallization risk. Staying hydrated also aids in flushing out calcium and oxalates.

Food-Based Calcium Is Better Than Supplements

The body efficiently absorbs calcium from food compared to supplements, as stated by Betz. Dairy products serve as excellent calcium sources, while plant-based foods often contain oxalates that limit absorption. Despite this, avoiding oxalates is unnecessary since they also provide beneficial nutrients like potassium and magnesium, which reduce stone risk.

In certain cases, supplements are beneficial. Individuals with digestive diseases or who have undergone gastric bypass surgeries may require calcium supplements to mitigate stone risk by binding oxalates effectively.