‘An apple a day’ is still considered pretty solid advice for boosting your health. But try this new health mantra on for size: A diet soda a day keeps the doctor away?

Sounds bizarre, but for people prone to developing painful kidney stones, this may actually be pretty sage advice.

Two separate studies have recently shown that chemicals in some diet sodas could block kidney stones from forming.

For most people who get kidney stones, calcium is the culprit. When calcium builds up in the urinary tract, crystals form and clump together. The first symptom is usually pain as the stone begins its perilous journey out through the urinary tract.

Ouch.

Here’s where the diet soda comes in. Certain citrusy diet sodas contain high levels of a chemical known as citrate, a key ingredient in supplements used to treat kidney stones. Ten years ago, researchers from Massachusetts General Hospital used a lemonade-like drink to successfully stymie kidney stones. Now, scientists say the sodas in question have even more citrate than the lemonade, potentially offering more protection against stones.

Researchers from the University of California San Francisco also recently tested a slew of sodas for stone-blocking chemicals citrate and malate. The scientists tested 15 types of diet soda. The verdict? Drinks like Diet 7-Up and Diet Sunkist seem to pack enough of these chemicals to keep calcium stones at bay

Of course, diet soda won’t be challenging the apple’s place in health anytime soon. Other studies have shown that drinking at least two diet sodas a day could hurt your kidneys over time.

And despite diet soda’s potential stone-fighting powers, doctors say another beverage should be the main weapon in any patient’s arsenal: water.