Results showed that the cumulative increment in serum calcium concentration was 2.5-fold greater with Citracal calcium citrate than calcium carbonate, meaning that calcium citrate was therefore much better absorbed than calcium carbonate, Dr. Heller explained. The article describes how research participants were involved in three phases of randomized study. In the third phase, two placebo tablets were taken. In all phases, subjects were given the calcium source of placebo at the same time in the morning with a standardized meal in the clinical setting. The participant's blood was drawn every hour for six hours in order to obtain a calcium bioavailability profile.
Calcium carbonate is thought to be best absorbed when taken with a meal.
Our results show that even under the most favorable conditions, calcium carbonate is not nearly as well absorbed as Citracal calcium citrate. Dr. Heller feels that the findings of this study may help explain why calcium citrate has achieved favorable results in trials at other research centers, such as the Mayo Clinic and the University of Connecticut. In addition, it may offer new insights for optimizing calcium delivery through supplementation. According to Dr. Heller, future clinical trials should test whether the superior bioavailability of calcium citrate results in greater protection against bone loss. Citracal has been available in 200 mg and 315 mg plus D tablet formulations and will soon be available in 250 mg plus D tablet formulation.