If 35 yr women having vitamin B12 deficiency how we can treat it?

Depends. Many have B12 deficiency from pernicious anemia. This leads to a decrease in the body's ability to absorb B12 through the GI tract. B12 injections are the best initial treatment. Some patients with pernicious anemia are able to keep their B12 levels up with oral supplements. However, if levels are already low, i'd recommend starting B12 injections and testing for pernicious anemia.