Vitamin B12 is a water-soluble vitamin that your body needs to make DNA and keep your nerve cells and red blood cells healthy. Most adults should consume at least 2.4 micrograms of vitamin B12 daily. Pregnant women need 2.6 micrograms every day, while lactating women need 2.8 micrograms. Vitamin B12 deficiencies are rare.
Animal products are good sources of vitamin B12, especially seafood. For example, a serving of liver provides 48 micrograms, while 85.1gr of clams provide 34.2 micrograms, and a 85.1gr serving of trout or salmon contains between 4.2 and 5.4 micrograms. In 85.1gr of beef sirloin there are 2.4 micrograms of vitamin B12, a double-patty cheeseburger has 1.9 micrograms, but half a chicken breast has only 0.3 micrograms.
Dairy products also contain high levels of vitamin B12. For example, a cup of yoghurt contains 1.4 micrograms, a cup of milk 0.9 micrograms, an egg 0.6 micrograms, and an ounce of Swiss cheese has 0.9.
Fortified breakfast cereal, fortified soy milk, nutritional yeast and fortified meat substitutes also contain vitamin B12. The B12 in these foods is grown from bacteria, not derived from animal products. Fortified foods help vegetarians and vegans get enough B12.
Dietary supplements can also help people get enough vitamin B12. If you choose to take a B12 supplement, look for products verified by the U.S. Pharmacopeia or Consumer Lab. Read the label carefully before use and never purchase supplements or drugs from unverified Internet pharmacies.
Elderly adults, vegetarians, vegans, people with pernicious anaemia and people with gastrointestinal disorders are most likely to have a B12 deficiency. Signs of a B12 deficiency include fatigue, weakness, weight loss, appetite loss, constipation and anaemia. Doctors usually treat B12 deficiencies with injections of B12.