Vitamin D significantly enhances calcium absorption from the gut.
Vitamin D stimulates production of calcium-binding proteins (calbindin) in the intestine, increasing active calcium absorption.
This is one of the most well-established supplement synergies. Ensure adequate vitamin D when supplementing calcium for bone health.
Known drug category interactions for these supplements. Especially relevant if you take prescription medications.
Calcium reduces levothyroxine absorption, potentially causing thyroid levels to fluctuate.
Take levothyroxine at least 4 hours before or after calcium supplements.
Reference values for safe daily intake of these supplements.
Risk of hypercalcemia at very high doses.
Excess may increase kidney stone risk and potentially cardiovascular risk.