Vitamin D
Cholecalciferol (vitamin D3) & Ergocalciferol (vitamin D2)
Description: A fat soluble vitamin which can be found in food sources such as marine fish, fish oils, fresh water fish, eggs. It is stored in fatty tissue in the body.
Cholecalciferol occurs in animals and ergocalciferol is found in plants. Cholecalciferol can be produced in the skin via activation of the provitamin 7-dehydrocholesterol by ultraviolet light (sunlight on skin). Further metabolism of vitamin D2 D3 to 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D occurs in the liver and kidneys respectively.
Properties: Enhances intestinal absorption of calcium. Involved in mobilization of calcium in bones.
Actions: 1,25-dihydroxyvitamin D3 can act with parathyroid hormone to promote mobilization of calcium from bones in order to increase the blood calcium levels.
Cautions: Excessive intake of vitamin D can lead to toxicity. High concentrations of vitamin D may result in hypercalcemia and soft tissue calcification.