MacG...definitely have it tested. I was getting B12 shots for years and still fell into extremely low levels and very low on iron. Lead to respiratory difficulty, dizziness (although I always am
), tingling extremities and face and general weakness. It is a lot easier to keep things stable if you watch it consistently than if you let it get to a bad level. And yes, the TI does have a major impact...I had mine removed in 1990 so I get little from digestion of foods.