Vitamin B12 is essential for making red blood cells, keeping nerves healthy, forming DNA, and helping your body carry out various functions. It’s necessary for maintaining both mental and physical health.

Not getting enough vitamin B12 to the point of a deficiency can cause a variety of serious symptoms including depression, joint pain, and fatigue. Sometimes these effects can be debilitating to the point where you might think you’re dying or seriously ill.

Vitamin B12 deficiency can be uncovered with a simple blood test, and is highly treatable. We’ll break down the signs you’re not getting enough vitamin B12, and treatment methods available to you.

Signs and symptoms of a B12 deficiency don’t always show up immediately. In fact, they can take years to become noticeable. Sometimes, the symptoms are mistaken for other conditions, like a folate deficiency or clinical depression.

According to the NIH, common physical symptoms of a vitamin B12 deficiency include:

  • anemia
  • feeling weak or fatigued
  • trouble keeping your balance
  • weight loss
  • appetite loss
  • numbness or tingling in the hands, legs, or feet
  • swollen or inflamed tongue (glossitis)
  • heart palpitations
  • pale or jaundiced skin

There can also be psychiatric symptoms as well, although the cause of these may not be apparent at first.

These symptoms include:

A deficiency of vitamin B12 can have serious physical and mental symptoms. If you’re not aware that these are related to a vitamin B12 deficiency, you might become alarmed that you’re seriously ill or even dying.

If not addressed, a B12 deficiency can cause megaloblastic anemia, a serious condition where the body’s red blood cells (RBC) are larger than normal and in shorter supply.

With proper diagnosis and treatment of a B12 deficiency, you can usually return to full health and feel like yourself again.

According to a 2021 research overview, vitamin B12 deficiency can be broken down into three main categories:

  • autoimmune issues (caused by types of anemia)
  • malabsorption (your body can’t uptake the vitamin)
  • dietary insufficiency (especially strict vegetarian or vegan diets that don’t include fortified grains)

A protein called intrinsic factor made in the stomach allows our bodies to absorb vitamin B12. Interference with the production of this protein can cause deficiency.

Malabsorption may be caused by certain autoimmune conditions. It can also be affected by weight loss surgeries that remove or bypass the end of the small intestine, where the vitamin is absorbed.

There’s evidence to suggest people can be genetically predisposed for a B12 deficiency. A 2018 report in The Journal of Nutrition explains that certain gene mutations or anomalies can “affect all aspects of B12 absorption, transport, and metabolism.”

Being a strict vegetarian or vegan may cause a vitamin B12 deficiency. Plants don’t make B12 — it’s found mostly in animal products. If you don’t take a vitamin supplement or eat fortified grains, you may not be getting enough B12.

People at risk of vitamin B12 deficiency can include those with:

If you fit any of these categories or are concerned about your nutrition, talk with your doctor about your vitamin B12 intake and whether you may be at risk for developing a deficiency.

As John Hopkins Medical explains, treatment for vitamin B12 deficiency depends on a number of factors. These include your age, if you have preexisting health conditions, and whether you’re sensitive to certain medications or foods.

Typically, acute treatment consists of vitamin B12 injections, which can get around barriers to absorption. Very high doses of oral vitamin B12 have been shown to be effective. Depending on the cause of your deficiency, you may require B12 supplements for the rest of your life.

Dietary adjustments may also be necessary in order to incorporate more foods high in vitamin B12. And there are plenty of ways to include more B12 into your meals if you’re vegetarian. Working with a nutritionist can help you figure out a plan that works for you.

Key foods rich in B12 include:

  • beef
  • fish (tuna, trout, salmon and sardines)
  • clams
  • organ meats like liver or kidneys
  • fortified cereal
  • fortified nutritional yeast
  • milk and dairy products
  • eggs

If you have a family history of vitamin B12 malabsorption or a chronic illness associated with B12 issues, consult with a doctor. They can run simple blood tests to check your levels.

For those who are vegetarian or vegan, it’s a good idea to talk with a doctor or a nutritionist about your eating habits, and whether you’re getting enough B12.

A routine blood test can detect whether you are deficient in vitamin B12, and medical history or other exams or procedures can help find the underlying cause of the deficiency.

Vitamin B12 deficiency is common, but extremely low levels can be dangerous and cause symptoms that interfere with your life. When untreated over time, the physical and psychological symptoms of this deficiency may be debilitating and make you feel like you’re dying.

If you believe you’re having symptoms of a B12 deficiency, consult your doctor. Let them know about your concerns regarding your B12 levels, your symptoms, and have your levels checked with a blood test.

Vitamin B12 deficiency is treatable, but getting an accurate diagnosis and understanding the underlying cause is important. Treatment may include oral supplementation, injections, and/or adjusting your diet. Once your vitamin B12 levels get back to normal and stabilize, your symptoms will usually resolve.