My 23 yo son was just informed that his Vitamin D level is low (working on getting the actual numeric value for this result). He eats 2 servings of yogurt daily, skim milk, granola, kale, etc. He walks outside frequently. Based on this, I wonder why his vit d level is low-his PA did not seem overly interested. He has lower back pain, suffers from IBS (maybe this is the cause of malabsorption of vit d?) and seems to get colds frequently. Also suffers from depression and anxiety. Autoimmune problems run in the family (RA and AS) so his PA is doing some blood work to check that, but no real clinical evaluation or images. I want him to see someone who is more qualified to answer his issues – have suggested my rheumatologist. Any ideas?