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Intestinal absorption of Ca(H2PO4)2 and Ca citrate compared by two methods
1Clinical Nutrition Research Unit, University of Chicago, IL 60637.
The American Journal of Clinical Nutrition
|May 1, 1988
Summary
Calcium citrate showed at least twice the absorption compared to calcium phosphate. The oral calcium load test offers a rough estimate of calcium availability for group analysis but not for individual assessment.
Area of Science:
- Nutritional Science
- Biochemistry
- Human Physiology
Background:
- Calcium bioavailability is crucial for bone health and overall well-being.
- Understanding the absorption differences between various calcium salts is essential for dietary recommendations.
- Accurate methods for assessing calcium absorption are needed.
Purpose of the Study:
- To compare calcium absorption from calcium phosphate (Ca(H2PO4)2) and calcium citrate.
- To evaluate the utility of the oral calcium load test as a measure of relative calcium bioavailability.
Main Methods:
- Eight healthy subjects ingested 750 mg of calcium from either Ca(H2PO4)2 or calcium citrate solutions, tagged with a 47Ca tracer.
- Calcium absorption was measured by tracking forearm radioactivity and analyzing urinary calcium levels (oral calcium load test).
Main Results:
- Calcium citrate demonstrated at least double the absorption compared to Ca(H2PO4)2.
- Urinary calcium increases post-load correlated with fractional absorption for calcium citrate (r = 0.803, p < 0.02).
Conclusions:
- Calcium citrate is a more bioavailable source of calcium than Ca(H2PO4)2.
- The oral calcium load test can serve as a rough index for group comparisons of calcium availability.
- Direct absorption measures are necessary for individual bioavailability assessments.