How many times have we heard this advice? Get your nutrients from foods, not supplements. When there is any effect, more than likely it is working through the placebo effect. As a general rule, if you eat less than 1200 kcal a day, you may consider taking a multivitamin/multi-mineral supplement. Also if you are a vegan, you should consider getting your vitamin B12 from fortified foods. A B12 deficiency is more likely due to a problem from poor absorption rather than from a low intake alone. Even though vitamin B12 is a water-soluble vitamin, blatant deficiency is rare because the body stores and reuses it efficiently. Check with your doctor about your vitamin B12 status and diet supplement use especially if you are elderly or on a restricted diet of any kind.