Effect of the Consumption of Ferric Hydroxide Adipate on Urinary Phosphorus Excretion.

Overview

Ferric hydroxide adipate is a ferric iron supplement containing iron hydroxide and a dietary organic acid that was developed at MRC Human Nutrition Research. We aim to determine if the ingestion of ferric hydroxide adipate with food induces a reduction in urinary phosphate concentration, compared with the administration of placebo plus the same food on a different occasion. We hypothesise that ferric hydroxide adipate binds some phosphate ions in the gastrointestinal tract, which prevents part of the phosphate load in a meal from being absorbed. On another visit, calcium will be given with the same food, as a positive control, since this element is well known to restrict dietary phosphate absorption through the formation of insoluble calcium phosphates in the gut lumen. We will compare urinary phosphate concentrations after co-ingestion of the calcium salt and food versus urinary phosphate following ferric hydroxide adipate and the same food. Additionally, the calcium data will be compared with placebo data, since a significant reduction in urinary phosphate concentrations after calcium treatment will confirm the suitability of the study design. Finally, iron absorption from the ferric hydroxide adipate treatment will be determined by labelling this preparation with 58Fe and measuring day 14 erythrocyte 57Fe:58Fe. The study design is: Three-way cross-over volunteer absorption study. Volunteers will not be told which treatment they receive (placebo, ferric hydroxide adipate, or supplemental calcium). Researchers co-ordinating the study on a day to day basis will be aware of treatment allocation, but analysts will not be told which samples correspond to which treatments.