A RANDOMIZED, VOLUNTEER, PHARMACOKINETIC STUDY COMPARING ABSORPTION AND BIOAVAILABILITY OF CORAL CALCIUM WITH CALCIUM CARBONATE AND CALCIUM CITRATE MALATE SUPPLEMENTS

Varsha Narayanan*, Shailesh Pallewar, Abhay Mane and Amit Bhargava

ABSTRACT

Introduction: Calcium is one of the vital minerals required by the body and may often be deficient due to multiple factors, requiring intake of calcium supplements. Available calcium supplements vary in calcium salts used and amount of elemental calcium available, dosage strength, as well as the absorption and bioavailability of the calcium present. Calcium from natural coral sources may offer benefits of a possible better absorption due to a bioactive structure. Objective: To compare calcium supplements from natural coral sources (coral calcium) with available calcium carbonate (from non-coral sources) and calcium citrate supplements in healthy volunteers by measuring rise in blood calcium and bioavailability, post intake of each of the calcium supplements. Methodology: The study was an open label, single centric study comparing 5 groups of 9 volunteers each taking different calcium supplements: two arms of coral calcium supplement tablets of elemental calcium strengths 225 mg and 500mg (Group A, B), 2 arms of non-coral calcium carbonate supplement tablets of elemental calcium strengths 400mg and 500mg (Group C, D), and one arm of calcium citrate malate supplement tablets with elemental calcium 250mg (Group E). Baseline fasting blood and urine samples were taken followed by dosing of the calcium tablet preparation. Blood and urine samples were thereafter collected at 2, 4, 6, and 10 hours to evaluate blood calcium levels, bioavailability and urinary calcium excretion. Results: For all groups, peak blood calcium levels were seen at 4 hours. The rise in blood calcium was found to be higher for coral calcium tablets (P<0.05 against tablets of non-coral calcium carbonate and calcium citrate malate). The calculated bioavailability by area under the curve (AUC) was also significantly more for Coral calcium tablets (P<0.005 versus tablets of non-coral calcium carbonate and calcium citrate malate). The urine calcium excretion also increased proportionately over 10 hours for each of the groups. No adverse events were seen in any of the groups. Conclusion: Calcium from Coral source may show better absorption and bioavailability as compared to other Calcium supplements containing non coral calcium carbonate and calcium citrate malate.

Keywords: Coral calcium, blood calcium, bioavailability, absorption, calcium carbonate.