how are minerals absorbed in the digestive system??
The main minerals which we cover here are calcium, iron, copper, zinc, phosphorus. Calcium is absorbed by two different ways: active and passive transport. Active transport takes place mostly in the duodenum and it is facilitated by voltage-insensitive (TRP) channels. It depends on the vitamin D levels. Passive transport occurs predominantly in the jejunum and ileum, where calcium diffuses through tight junctions between adjacent intestinal epithelial cells. Phosphorus is transported into intestinal epithelial cells by co-transport with sodium expression of which is also vitamin D –dependent. Iron absorption is facilitated by DMT-1. Prior to absorption it is required for iron to reduce from Fe3+ to Fe2+. When iron is getting into the intestinal epithelial cells it then converts back to Fe3+ state. Copper is absorbed predominantly in the stomach and upper small intestine. Copper is transported through several copper transporters (e.g. Ctr1) Zinc is absorbed in the small intestine through two main families of zinc transporters: ZnT1 and ZIP.