causes of very low vitamin d levels
But many people who avoid meat don't become deficient in vitamin B12. Many other foods, especially fish, contain vitamin B12. There are a couple of diseases that could cause low levels of vitamins D and B12. Celiac disease (gluten sensitivity) might cause vitamin and mineral deficiencies without specific symptoms. Crohn's disease could also cause both, but most people with Crohn's will have symptoms such as abdominal pain and frequent stools.