Our skin is responsible for Vitamin D production and naturally it won’t produce more than we need. That means we need regular and constant exposure to sunshine for Vitamin D production. Foods such as milk and fish do not provide as much as Vitamin D as sunshine. Therefore it is very important not to be underexposed to the sun.
Laboratories are now able to measure blood levels of Vitamin D. Your doctor can order a test known as 25-hydroxy-Vitamin D levels. Normal levels are between 30-100 nanograms per milliliter of blood. Levels between 15ng-30ng is considered insufficient. Levels less than 15ng is considered deficient.
Recent studies have shown that more than half of children have either insufficient or deficient levels of Vitamin D. Although large studies have not been done in adults, it is very much expected that a significant number of adults have insufficient or deficient levels of Vitamin D.
Therefore, the next time you see your doctor, get your blood level of Vitamin D checked. Levels between 30ng-100ng is normal. If your levels are lower, you should supplement with at least 1000 IU per day of Vitamin D. If you have osteopenia or osteoporosis, those levels should be higher and you should also take a Calcium supplement.