Sorry for the delay…major computer issues. I know of two people going through different symptoms that both apply. One is gluten sensitive (which can cause B12 absorption issues) and the other is/was vegetarian (B vitamins are primarily in meat and fish). Both had severe symptoms (the first seizures, and was tested). From my understanding, B12 is the most common nutrient deficiency; although the body can store it for a long time, so it can take a while to notice problems. Note that medical doctors test the blood for B12, but they typically do not test for absorption of it, even if they suspect a problem. They also do not acknowledge the reality of gluten sensitivity, even though it can be determined by a DNA test.