Calcium Bioavailability from Mineral Waters with Different Mineralization in Comparison to Milk and a Supplement

The aim of the present study was to compare the bioavailability of calcium from 3 mineral waters with different concentrations of minerals with that of milk and a calcium supplement.

A single-center, randomized controlled trial with a crossover design with 21 healthy men and women was conducted at the Institute of Food Science and Human Nutrition, Leibniz University Hannover. The participants consumed the 5 test products providing 300 mg of calcium each on 5 examination days with 1-week wash-out phases in between. Primary outcome variables were the area under the curve of serum calcium levels for 10-hour (AUC_0-10h) and 24-hour urinary calcium excretion.

In all groups, no significant differences in the AUC_0-10h of serum calcium levels as well as in the 24-hour urinary calcium excretion were observed. Likewise, mean changes in serum phosphate and urinary phosphate, as well as serum parathormone, showed no differences between the groups.

Given an equivalent bioavailability of calcium in all test products, neither a high concentration of SO₄^2- or of HCO₃ influenced the bioavailability of calcium. Accordingly, the use of mineral water with high concentrations of calcium constitutes a calorie-free calcium source that can improve calcium supply.