Objective
To determine whether the ratio of dietary calcium and oxalate consumption at mealtime
affects gastrointestinal oxalate absorption and urinary oxalate excretion.
Methods
A study was conducted with 10 non–stone-forming adults placed on controlled diets
with daily calcium and oxalate contents of 1000 and 750 mg, respectively. Subjects
consumed a balanced calcium/oxalate ratio diet for 1 week, observed a minimum 1-week
washout period, and subsequently consumed an imbalanced calcium/oxalate ratio diet
for one week. Urine specimens were collected on the last 4 days of each diet. Outcome
measures included urinary creatinine, calcium, and oxalate as well as the Tiselius
index for assessing urinary calcium oxalate supersaturation.
Results
Total daily calcium excretion, oxalate excretion, and Tiselius index were similar
between balanced and imbalanced dietary phases. There were significant differences
in calcium excretion (mg/g creatinine) between balanced and imbalanced diets in the
1-6 pm (83.1 vs 110.2, P <.04), 6-11 pm (71.3 vs 107.2, P <.02), and 11 pm-8 am collections (55.0 vs 41.8, P <.02). There was significantly higher oxalate excretion on the balanced diet in the
1-6 pm time period (28.1 vs 16.7, P <.01). There were no differences in the Tiselius index in these collections.
Conclusion
These results demonstrate that the sequence of ingesting relatively large amounts
of oxalate does not significantly affect calcium oxalate stone risk if the recommended
daily quantity of dietary calcium is consumed.
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Article info
Publication history
Published online: April 05, 2012
Accepted:
January 31,
2012
Received:
November 14,
2011
Footnotes
Financial Disclosure: The authors declare that they have no relevant financial interests.
Funding Support: National Institutes of Health grants R01 DK62284 and M01 RR07122.
Identification
Copyright
© 2012 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
