One symptom of B12 deficiency is…

  • Insomnia
  • Fatigue
  • Blurred vision
  • Weight gain

Fatigue is the most common symptom of people who have low levels of vitamin B12. But fatigue by itself can be a sign of almost any health condition — or just that you haven't been sleeping enough! Other signs of B12 deficiency include confusion, cognitive impairment, unsteady gait, numbness, tingling, and fatigue.


Which factor(s) can increase your risk of vitamin B12 deficiency?

  • Alcoholism
  • Following a vegan diet
  • Crohn's disease or celiac disease
  • Age
  • Weight loss surgery
  • All of the above

Vitamin B12 deficiencies may happen when you aren't getting the right nutrients in your diet, when your body can't absorb nutrients properly, and when you have various other problems of the digestive system.Since most B12 in our diets comes from animal products, vegans are at risk for B12 deficiency. Crohn's and celiac disease, weight loss surgery, and chronic alcoholism can all interfere with a person's ability to absorb enough of the nutrients they need. Seniors have more problems with nutrient absorption and malnutrition as well.


What happens when you don't get enough B12?

  • Your body can't make enough red blood cells.
  • You're more likely to get a cold or the flu.
  • You get hot flashes.
  • You develop allergies.

Vitamin B12 is a critical nutrient that helps your body make healthy red blood cells. If you have a chronic lack of B12, your body can't make the amount of red blood cells that it needs, which can lead to anemia.


If you have extremely low levels of B12 in your body, what could happen?

  • Mental confusion and dementia
  • Severe rages
  • Stomach cancer
  • Liver cancer

Most people with vitamin B12 deficiencies have a mild problem. But in some cases, vitamin B12 deficiency can have serious consequences. You can develop mental problems, including confused thinking, memory loss, and dementia, which in some serious cases can be irreversible. Low levels of B12 can also cause nerve damage and anemia and weaken your bones.


Which food has the most vitamin B12?

  • Honey
  • Orange juice
  • Steak
  • Tomatoes

Animal products like meat, poultry, and seafood, and dairy foods like milk, eggs, yogurt, and cheese are the best sources of vitamin B12. Honey, vegetables, and fruits are not really sources of vitamin B12, which is why people who follow a vegan diet may not get enough of it. If you're a vegan, think about eating a breakfast cereal fortified with B12. You can also take a B12 supplement, which is recommended for pregnant and nursing mothers who are vegans or even strict vegetarians.Sometimes B12 deficiency is caused by conditions other than diet. If your body can't absorb B12 properly, you'll need a doctor's help to boost your B12 to safe levels.


How can you tell if you have a true B12 deficiency?

  • Take an online quiz.
  • Take a urine test at your doctor's office.
  • Take a blood test at your doctor's office.
  • Describe your symptoms to your doctor.

Describing your symptoms to your doctor may give them a clue that you could have low levels of vitamin B12. But you'll need blood tests to confirm it. Some people can easily fix low levels of B12 by simply changing their diet, while others will need a doctor's help.


What medications can make it hard for your body to absorb vitamin B12?

  • Some diabetes medications
  • Some antibiotics
  • Antacids
  • Some seizure medications
  • All of the above

All of these drugs can interfere with your body's ability to break down vitamin B12 from food.


How can you treat a B12 deficiency?

  • Get more sunshine
  • Take a vitamin
  • Eat raw vegetables
  • All of the above

For some people, taking a vitamin supplement or eating more animal products (or both) can help boost their B12 levels back to where they should be. But other people may have a severe deficiency or may have an underlying health condition that causes their B12 to drop.Doctors can treat a B12 deficiency in several ways. If your symptoms are mild or moderate, you may start with an oral B12 supplement, which you take once a day; a vitamin B12 nasal spray used weekly; or vitamin B12 injections, which you need less frequently.

Show Sources


      Peter Cade / Stone



      National Heart, Lung and Blood Institute: "What Are the Signs and Symptoms of Pernicious Anemia?"

      Medline Plus: "Anemia - B12 Deficiency."

      Oh, R. American Family Physician, March 1, 2003; vol 67(5): pp 979-986.

      National Heart, Lung and Blood Institute: "What Is Pernicious Anemia?"

      Epocrates Online: "Vitamin B12 Deficiency."

      National Institutes of Health Office of Dietary Supplements: "Dietary Supplement Fact Sheet: Vitamin B12."

      USDA National Nutrient Database for Standard Reference: "Honey."

      National Heart Lung and Blood Institute: "Who is at Risk for Pernicious Anemia?"