The question is how much vitamin D do you need? You can easily find out how much vitamin D you have by a simple blood test. Ask your doctor to order a 25 hydroxy vitamin D level. Most experts believe that a level of 30 nanograms per milliliter is enough. But some studies suggest that a level of 40 or even 50 is needed to provide sufficient vitamin D for all its functions.
The foods that contain the most vitamin D, like cod liver oil and wild salmon, just don’t have enough to get you up to those levels unless you are a baby or a toddler. You have to either expose your skin to a little sun if possible or take a supplement of vitamin D.