Process of intestinal uptake and transport of dietary calcium into circulation.
Calcium absorption refers to the process by which dietary calcium is taken up by the intestinal epithelium and transported into the bloodstream for utilization throughout the body.
Calcium absorption occurs primarily in the small intestine through two mechanisms: an active, vitamin D-dependent saturable pathway that predominates when calcium intake is low, and a passive paracellular pathway that increases with higher calcium concentrations. Vitamin D is the primary regulator of active calcium absorption, converting to its active form calcitriol in the kidneys to increase intestinal calcium-binding protein synthesis. Absorption efficiency varies based on calcium source, with animal sources generally showing 25-35% absorption while plant-based sources may show lower rates due to oxalates and phytates. Factors including stomach acid, lactose, and overall digestive health significantly influence how much dietary calcium actually enters circulation.
Calcium absorption enables adequate calcium availability for bone mineralization, muscle contraction, and neural signaling.
Ensure adequate vitamin D status through sunlight exposure, fortified foods, or supplementation to maximize calcium absorption. Consume calcium sources with meals and distribute intake throughout the day in portions under 500 mg for optimal absorption. Maintain adequate magnesium and avoid excessive phosphate intake to preserve calcium absorption efficiency.
Vitamin D is essential for calcium absorption, and optimal absorption requires distributed intake and adequate stomach acid.
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