Lk. Massey et Sa. Kynastgales, SUBSTITUTING MILK FOR APPLE JUICE DOES NOT INCREASE KIDNEY-STONE RISKIN MOST NORMOCALCIURIC ADULTS WHO FORM CALCIUM-OXALATE STONES, Journal of the American Dietetic Association, 98(3), 1998, pp. 303-308
Objective Increasing intake of dietary calcium from less than 400 mg t
o 800 mg daily may decrease the absorption of dietary oxalate, which i
n turn would decrease urinary oxalate excretion. The effect of substit
uting milk for apple juice on urine composition and risk of calcium ox
alate precipitability was studied. Subjects Twenty-one normocalciuric
adults with a history of at least 1 calcium oxalate stone and urinary
oxalate excretion exceeding 275 mu mol/day on their self-selected diet
. Design Randomized crossover trial. Intervention Each participant con
sumed two moderate-oxalate (2,011 mu mol/day) study diets, which were
identical except that one contained 360 mt milk and the other containe
d 540 mt apple juice as the beverage with meals. Setting Four days fre
e-living then 2 days in the metabolic unit of a university nutrition d
epartment. Main outcome measure Tiselius risk index for calcium oxalat
e precipitability calculated from urine composition. Statistical analy
ses Paired t tests. Results Twenty-four hour urinary oxalate excretion
was 18% lower (P<.0001) on the milk diet vs the juice diet: 423 vs 51
4 mu mol, respectively. Calcium excretion was 17% higher (P<.05) on th
e milk vs juice diet: 4.7 vs 3.9 mmol, respectively. Urinary magnesium
and citrate excretion, volume, and Tiselius risk index did not differ
between diets. Applications Substituting 360 mt milk daily for apple
juice with meals in a diet containing moderate amounts of dietary oxal
ate from whole grains, legumes, fruits, and vegetables does not increa
se the risk index of calcium oxalate precipitability in most normocalc
iuric adults who form stones.