vitamin b12 may be one of the most important vitamins our body needs. But that doesn’t mean megadoses of the nutrient are a good thing. Most healthy people get enough vitamin B12 from food.
About 1%-2% of people have a confirmed vitamin B12 deficiency, says M. Elizabeth Swenor, DO, who leads Henry Ford Health System’s Lifestyle, Integrative, and Functional Medicine in Detroit. If you're one of these people, you may benefit from higher doses of B12 but only under the supervision of a health care professional.
B12 is one of eight B vitamins. It helps produce the red blood cells that carry oxygen throughout our body. It’s also critical for nerve function, energy release, and even contributes to DNA formation, says registered nutritionist Lauri Wright, PhD, a national spokesperson for the Academy of Nutrition and Dietetics.
Your body doesn’t naturally make vitamin B12. That means you have to get it from food or supplements. Once ingested, the vitamin combines with a protein in your stomach called intrinsic factor. “Intrinsic factor is like a taxicab that transports B12 from the stomach to the part of the bowel where it’s absorbed,” Swenor says.
Most healthy adults only need a small amount of B12 -- 2.4 micrograms (mcg). B12 is plentiful in animal products like meat and fish, milk and other dairy products, eggs and, clams, which have a huge amount of B12. Some breakfast cereals, breads, and grains are also fortified with B12.
Three ounces of tuna will provide all the vitamin B12 you need for the day. Two eggs will give you half of the recommended daily amount, Wright says.
People most at risk for vitamin B12 deficiency include those over the age of 65, vegans and vegetarians (who often don’t eat enough animal products), people who have gastrointestinal diseases like Crohn’s disease or celiac disease, and anyone who has had part of their gastrointestinal tract removed through gastric bypass or another type of surgery, Wright says.