What is the most important nutrition intervention to prevent nephrolithiasis?

• A. Low-oxalate diet
• B. Avoidance of calcium entirely
• C. Restriction of protein
• D. Maintaining adequate hydration to support a urine output > 1200 mL/day

Answer: (D)

Maintaining a high fluid intake to keep urine well diluted is the most effective nutrition-based strategy to prevent kidney stones. When urine is more dilute, the concentrations of stone-forming substances (like calcium, oxalate, uric acid) are lower, which reduces the tendency for crystals to form and grow. A practical target is to produce urine output around 1.2 liters per day or more, which helps keep these solute concentrations below the levels that promote crystallization.

This hydration focus serves as a foundation because many stone types share the risk of low urine volume; other dietary modifications—such as restricting oxalate, avoiding calcium entirely, or limiting protein—can be helpful for specific stone types or individual risk factors but are not as universally protective as ensuring adequate hydration. It’s also worth noting that, in most stone formers, maintaining adequate calcium intake is important for gut oxalate handling rather than restricting calcium to prevent stones.