On the Importance of Proper Circadian Rhythm

Part 5 - Vitamin D the Sunshine Hormone That Will Change Your Life

Vitamin D is a group of fat-soluble secosteroids that can be produced endogenously (within our body) from sunlight exposure that contains UVB or obtained from supplementation or in smaller quantities from our diet. Vitamin D has many different analogs and forms. Vitamin D₂ (ergocalciferol). Ergocalciferol is vitamin D₂ that is produced by fungi when they are exposed to UVB. Vitamin D₃, or cholecalciferol, is the analog that our skin makes when exposed to UVB. Cholecalciferol is also the vitamin D analog we ingest in our food and the analog is derived from exposing lanolin to radiation, animal liver, or lichen in supplements. Cholecalciferol we ingest is absorbed into circulation within the small intestine through passive diffusion or cholesterol transporters. Our skin absorbs cholecalciferol and enters our bloodstream, which is bounded by vitamin D-binding protein and then transported to our liver through the hepatic artery. The vitamin D-binding protein releases cholecalciferol and is then converted into calcifediol (25-hydroxy vitamin D) within our liver and is stored. Cholecalciferol conversion into calcifediol is regulated by the CYP2R1 gene, which encodes the 25-hydroxylase enzyme. Ergocalciferol converts poorly to calcifediol, so I do not recommend it. Finally, there are numerous synthetic analogs of vitamin D, but I do not recommend any of them because I believe no analog or form will be better than what we produce ourselves.[1] [2] [3] [4] [5] [6] [7]

Our kidneys are what mainly convert 25-hydroxy (calcifediol) into 1,25-hydroxy (calcitriol) by the CYP27B1 gene encoding the enzyme 25-hydroxyvitamin D3-1-alpha-hydroxylase; when it is released, bounded by vitamin D-binding protein into our bloodstream by our liver when needed which is the active form of vitamin D. Calcitriol is released into the bloodstream bounded up by vitamin D-binding protein when required by our body. Calcitriol is the form of vitamin D that your body uses to regulate calcium and phosphate concentrations, support our innate immune system, support healthy bone growth and remodeling, and help improve our overall health by binding to numerous vitamin D receptors (VDR) throughout our body. Finally, recent vitamin D conversion studies have confirmed that many localized tissues throughout our body can convert cholecalciferol when needed instead of only our kidneys converting cholecalciferol into calcitriol.[8] [9] [10] [11]