From the Guidelines
Patients with a history of nephrolithiasis should maintain a normal dietary calcium intake, rather than taking calcium supplements, to reduce the risk of stone formation.
Key Recommendations
- Maintain a normal dietary calcium intake of 1000-1200 mg daily 1
- Avoid taking calcium supplements, as they may increase the risk of stone formation, especially if taken between meals 1
- If calcium supplements are necessary, patients should collect 24-h urine samples on and off the supplement to monitor urinary supersaturation of the calcium salt in question 1
- Patients with enteric hyperoxaluria and high levels of urinary oxalate may benefit from more restrictive oxalate diets and higher calcium intakes, which may include supplements, specifically timed with meals 1
Rationale
- Dietary calcium can bind to oxalate in the gut, reducing oxalate absorption and urinary excretion, which can help prevent stone formation 1
- Calcium supplements, on the other hand, may not provide the same benefit, as they are often taken between meals and do not bind to oxalate in the same way 1
- Maintaining a normal dietary calcium intake is important for overall health, and patients with a history of nephrolithiasis should aim to get their daily calcium from food sources rather than supplements 1
- Patients with specific conditions, such as enteric hyperoxaluria, may require more individualized dietary recommendations and may benefit from higher calcium intakes, including supplements, to help manage their condition 1
From the Research
Calcium Supplement Recommendations for Patients with Nephrolithiasis
- Patients with a history of nephrolithiasis should not restrict dietary calcium, as a calcium intake of ≥ 1 g/day may be protective against the risk of stone formation 2.
- Calcium supplementation given between meals might increase urinary calcium excretion without the beneficial effect on oxalate, and its administration may worsen the risk for stone formation in patients predisposed to hypercalciuria 3.
- However, some studies suggest that calcium supplementation may reduce the risk of renal stone disease by increasing the proportion of urine calcium to oxalate and reducing urine oxalate 4.
- The impact of calcium intake and intestinal calcium absorption on kidney stones in older women has been explored, and the results suggest that increased dietary calcium intake reduces the likelihood of nephrolithiasis by 45% to 54% 5.
Key Considerations
- A balanced consumption of calcium is recommended, with a daily intake of 800-1200 mg for adults 2.
- Patients with nephrolithiasis should aim to achieve a daily urine output of 2 liters through increased fluid intake 2.
- Moderate dietary salt restriction and implementation of potassium intake may be useful in limiting urinary calcium excretion 2.
- The administration of alkaline-citrates salts may be recommended for patients with hypocitraturia, and increased intake of fruit and vegetables (excluding those with high oxalate content) may increase citrate excretion and involve a significant protection against the risk of stone formation 2.
Special Considerations for Specific Populations
- In children, moderate dietary salt restriction and implementation of potassium intake are useful in limiting urinary calcium excretion, whereas dietary calcium restriction is not recommended for children with nephrolithiasis 2.
- In older patients, a restriction of sodium intake in association with a higher intake of potassium, magnesium, and citrate is advisable to reduce urinary risk factors for stone formation 2.
- A diet rich in calcium (1200 mg/day) is useful to maintain skeletal wellness and to prevent kidney stones in older patients, although higher supplementation could involve an increase of risk for both the formation of kidney stones and cardiovascular diseases 2.