Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria

N Engl J Med. 2002 Jan 10;346(2):77-84. doi: 10.1056/NEJMoa010369.

Abstract

Background: A low-calcium diet is recommended to prevent recurrent stones in patients with idiopathic hypercalciuria, yet long-term data on the efficacy of a low-calcium diet are lacking. Recently, the efficacy of a low-calcium diet has been questioned, and greater emphasis has been placed on reducing the intake of animal protein and salt, but again, long-term data are unavailable.

Methods: We conducted a five-year randomized trial comparing the effect of two diets in 120 men with recurrent calcium oxalate stones and hypercalciuria. Sixty men were assigned to a diet containing a normal amount of calcium (30 mmol per day) but reduced amounts of animal protein (52 g per day) and salt (50 mmol of sodium chloride per day); the other 60 men were assigned to the traditional low-calcium diet, which contained 10 mmol of calcium per day.

Results: At five years, 12 of the 60 men on the normal-calcium, low-animal-protein, low-salt diet and 23 of the 60 men on the low-calcium diet had had relapses. The unadjusted relative risk of a recurrence for the group on the first diet, as compared with the group on the second diet, was 0.49 (95 percent confidence interval, 0.24 to 0.98; P=0.04). During follow-up, urinary calcium levels dropped significantly in both groups by approximately 170 mg per day (4.2 mmol per day). However, urinary oxalate excretion increased in the men on the low-calcium diet (by an average of 5.4 mg per day [60 micromol per day]) but decreased in those on the normal-calcium, low-animal-protein, low-salt diet (by an average of 7.2 mg per day [80 micromol per day]).

Conclusions: In men with recurrent calcium oxalate stones and hypercalciuria, restricted intake of animal protein and salt, combined with a normal calcium intake, provides greater protection than the traditional low-calcium diet.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcium / urine*
  • Calcium Oxalate / urine
  • Calcium, Dietary / administration & dosage*
  • Diet Therapy*
  • Diet, Sodium-Restricted*
  • Dietary Proteins / administration & dosage*
  • Humans
  • Incidence
  • Kidney Calculi / etiology
  • Kidney Calculi / prevention & control*
  • Male
  • Middle Aged
  • Oxalates / urine
  • Secondary Prevention

Substances

  • Calcium, Dietary
  • Dietary Proteins
  • Oxalates
  • Calcium Oxalate
  • Calcium