Is a fat-soluble prohormone that is synthesized in the skin by cholesterol from UVB radiation from the sun; important in proper immune system function.
Vitamin D3 aids in- reduces the incidence and severity of canker sores; Improving general colon health; maintaining normal blood and intestinal levels of calcium; strengthening our bones; protecting the blood-brain barrier by: increasing occludin (claudin-5 ZO-1) proteins; blocking MMP9; protects the blood-brain barrier when disrupted due to inflammation from a high-fat and high-calorie diet; regulates production of many enzymes.
Infections- alter the ability to use vitamin D for our immune system. If you have had your 25 OH Vitamin D3 levels checked and they are above normal, but you don't feel good, then investigate chronic infections.
Sources of Vitamin D- The sun creates sulfated vitamin D (better than vitamin D supplement; try to get more than 50 mg/dL per day in foods such as: cheese; cod liver oil; egg yolks; fish and seafood; liver; fortified foods, such as juices, cereals, dairy, plant-based milk, and tofu; through sun exposure (15-30 minutes at minimum).
Vitamin D Deficiency can cause- children can have rickets (skeletal abnormalities); osteomalacia with possible bone pain and muscle weakness; Hypocalcemia (below-normal blood calcium) which stimulates the release of parathyroid hormone (PTH).
Vitamin D Toxicity- Vitamin D is highly toxic at high levels that exceed 10x the RDA which results in hypercalcemia; can impair renal function.
Increasing vitamin D- L. reuteri can increase blood levels of vitamin D3.
RDA- 800 IU to 6000 IU + per day depending on sun exposure and gene variants that reduce absorption with a 2,000 IU minimum if a deficiency is found.
Testing Vitamin D levels- there are options you can also purchase online to monitor your vitamin D levels at home; have your doctor order a blood testing on 25 OH Vitamin D3 and 1,25 OH (active) Vitamin D3 levels.
Vitamin D Supplements- vitamin D3 is often derived from animal sources; vitamin D2 is suitable for vegans as well as lichen derivatives.