I'm a single data point in this story. I've been vegan since 1991. I also have Crohn's disease. I had a bowel resection in 2001 and subsequently my B12 blood

I'm a single data point in this story. I've been vegan since 1991. I also have Crohn's disease. I had a bowel resection in 2001 and subsequently my B12 blood tests revealed a deficiency. I was then prescribed a course of monthly B12 injections. These went down to 3 monthly and for the last 5 years my yearly blood test have deemed them unnecessary. However, I now have Vitamin D deficiency instead. Plus ça change.