How Much Vitamin B-12 Should a Woman Get?

Vitamin B-12, or cobalamin, is essential for the replication of DNA and healthy nerve cells. It supports neurological function and is crucial in the creation of red blood cells. Stomach acid and intrinsic factor, a substance in your stomach, are necessary for the proper absorption of B-12. Symptoms of inadequate amounts of vitamin B-12 can include fatigue, constipation, lack of appetite, numbness or tingling in the hands and feet and weight loss.

One ounce of Swiss cheese provides 0.9 microgram of vitamin B-12. (Image: Radu Sebastian/iStock/Getty Images)

Recommended Dietary Allowances

Women require varying amounts of vitamin B-12 at different stages throughout their lives. Adult women should get at least 2.4 micrograms of vitamin B-12 daily. There are additional requirements during pregnancy, when the RDA is 2.6 micrograms. Lactating women should get 2.8 micrograms daily. Meat, fish, poultry, eggs and dairy are good sources of B-12. Fortified breakfast cereals are a nonanimal source of vitamin B-12. Vegetarians, older people and those with absorption issues are more likely to be deficient, so a supplement may be warranted in those individuals. Scientific studies have found no adverse effects if you exceed the daily RDAs, even long-term, according to the Office of Dietary Supplements. Vitamin B-12 may interact with some medications, and other medications might impact your ability to absorb B-12. Consult a health care provider before supplementing, especially if you take proton pump inhibitors, histamine receptor antagonists or metformin, which is a drug for treating diabetes.