A:  That’s a good question.  This is important because, according to WebMD,  B12 deficiency can boost levels of homocysteine, which is a risk factor for heart disease and stroke.  Bill and I were already taking supplemental B12 when we changed our diet, so we just continued to do so.   But you are right if you are consuming a mostly plant-based diet you need B12 either through supplementation or fortified foods.  Additionally, it seems for many seniors B12 is not absorbed well so supplementation is often recommended.  You can read more at WebMD here.