500 mcg of b12 for women over 60?

It depends: About 40% of those over 60 are deficient in B12 (and many under 60 as well). While the dri is only 2.6 mcg it is poorly absorbed so only about 10 mcg of a 500 mcg dose is absorbed. If one eats lots of animal foods ; had adequate hydrochloric acid ; good digestion they may not need to take any, but 1000 mcg of methylcobalamin is good if deficient or for insurance- see http://bit.Ly/1607tg3.