Sheryl Kraft, a freelance writer and breast cancer survivor, was born in Long Beach, New York. She currently lives in Connecticut with her husband Alan and dog Chloe, where her nest is empty of her two sons Jonathan. Sheryl writes articles and essays on breast cancer and contributes to a variety of publications and websites where she writes on general health and wellness issues. She earned her MFA in writing from Sarah Lawrence College in 2005.Full Bio
Learn about our editorial policies
Our body is a pretty smart and amazing machine. To function properly, it works in an intricate and carefully timed dance interconnected with organs, muscles, nerves and tissues that helps it circulate, digest, breathe and propel functions necessary to sustain life. No part of the body works in isolation, and each part is responsible for doing its part.
Yet, there are certain things that our bodies don't automatically do, and one is absorbing the vitamin B12 that the body produces. B12 helps keep your nerve and blood cells healthy and is important for making DNA (our cell's genetic material). It also helps prevent a specific type of anemia (megaloblastic anemia) that causes fatigue and weakness.
Fortunately, there are ways to get this vitamin naturally: animal-based foods like beef, liver and clams are two of the best sources. Additional sources include fish, meat, poultry, eggs, milk and other dairy products, as well as foods fortified with B12, like some breakfast cereals and nutritional yeasts. (Unlike other B vitamins, there's no requirement that B6 and B12 be added to refined grains. A quick check of the food label can tell you if vitamin B12 has been added.)
Because the body doesn't store B12 for long, it's important to get some regularly.
Additionally, to absorb this vitamin, your body needs two things: hydrochloric acid in your stomach to break down the vitamin from the protein to which its attached in food, and the ability to bind with a protein called intrinsic factor, which is made by your stomach.
While most of us get enough vitamin B12 from the foods we eat, between 1.5 percent and 15 percent of people have a deficiency. A B12 deficiency can be detected by a simple blood test.
Here are some reasons why a deficiency may occur:
- Many older adults do not have enough hydrochloric acid in their stomachs to properly absorb the vitamin that's naturally present in foods they eat. That's why it's suggested that if you're over 50, you get most of your vitamin B12 from fortified foods or dietary supplements.
- People with pernicious anemia—a condition where the blood is low in normal red blood cells—don't have enough intrinsic factor to absorb vitamin B12. They usually require vitamin B12 shots or high oral doses of B12.
- Gastrointestinal surgery (like weight loss surgery) or digestive disorders (like celiac or Crohn's disease) may decrease the body's ability to absorb enough vitamin B12.
- Vegetarians or vegans who eat little or no animal food may become deficient. If you are a vegetarian or vegan who breastfeeds, your baby can become deficient, as well.
- Certain medications, like metformin, proton pump inhibitors like omeprazole (Prilosec) and lansoprazole (Prevacid) and H2 receptor antagonists like cimetidine (Tagamet) and famotidine (Pepcid) can also decrease absorption.
Because your body needs this vitamin to function properly, a vitamin B12 deficiency can have some unpleasant side effects. Among them:
- Appetite loss
- Weight loss
- Megaloblastic anemia
- Nerve problems like numbness or tingling in your hands and feet
- Problems with balance
- Poor memory
- Soreness of the mouth or tongue
Most adults need about 2.4 mcg of vitamin B12 each day. If you're not getting enough through the food you eat, you can get it through supplements. Most multivitamins contain a small amount of B12, and there are dietary supplements that contain vitamin B12 alone or combined with nutrients like folic acid and other B vitamins.