B-12 vitamins

How Much B12 is enough for women? 1mg ... 0.5mg ??? I am not sure. I know that is in eggs and cheese. Where else? Can you have too much or too little of B12 vitamins? What about vegetarians, my wife is one, does it mean that she has B12 deficiency?

Both men and women need 2.0 micrograms of vitamin B12 each day. Yes, sources are eggs and cheese, also meat, milk products, chicken, fish. B12 deficiency can cause a type of anemia marked by fewer but larger red blood cells that's called pernicious anemia, walking and balance problems, sore tongue, weakness, confusion and, in advanced cases, dementia. Vegetarians who eliminate all animal sources from their diet may benefit from taking a vitamin B12 supplement, but if she is pregnant or breastfeeding, she should not take vitamin B12 in doses greater than 2.6 micrograms/day.