How vitamin D works in our bodies
In spite of what has been said about the need for sunshine, people will not choose it for various reasons. These people will need to depend on a supplement. This needs to be D3, the same as getting sun. D2, which is synthetic and harmful, is often prescribed by doctors and is used as fortification in milk & cereals. D3 is found naturally in eggs & animal fat. Unlike the sun (D3), which can’t be overdone as long as we don’t burn, the supplement can be overused. The need for a daily dose is 3800 IU daily for people with adequate blood levels, 5000 IU for those deficient.
To determine a deficiency, we need to be tested at least once a year by ordering the Vitamin D, 25-Hydro blood test. In spite of what the range says, we should never be below 82. Below 50 is serious deficiency, with optimal range between 115-128.