Brain Fog and Vitamin D Deficiency...

Question: I was extremely tired and my Dr. did blood work and came up with a very low Vitamin D deficiency of around 13 ng/ml.

My understanding is that it should be around 30-100 ng/ml. Is that correct?

Also, I assume this had to be going on for quite a while since it was so low. I have
had some trouble at work with processing my thoughts and understanding some procedures.


Could the Vitamin D deficiency be a contributing factor to my brain fog?