Julie Hambleton
Julie Hambleton
July 17, 2023 ·  4 min read

Signs of Vitamin B-12 Deficiency You Should Never Ignore

One of the most crucial, though often overlooked, vitamins to our health is vitamin B-12. Without enough vitamin B-12 in our diets, we can feel tired, have trouble focusing, and so much more. Unfortunately, it is estimated that approximately 15% of the general population is deficient. These are the signs of vitamin B-12 deficiency and what you should do to prevent it.

What Is Vitamin B-12?

Vitamin B-12, also known as Cobalamin, is a vitamin that is found naturally in most animal products. It is necessary for the formation of red blood cells and DNA. Its requirement for red blood cells means that it is a necessary vitamin in transporting other nutrients around the body and providing us with energy. Vitamin B-12’s involvement in DNA formation also makes it important for cognitive development and functioning. It is a key component in the function and development of both brain and nerve cells. (1)

Vitamin B-12 first binds to the proteins in the foods that we eat. From there, enzymes and hydrochloric acid in our stomach break down those foods and unbind the vitamin B-12 into its free form. Once it is free, it then binds with a protein called intrinsic factor so that our small intestine can absorb it into our bloodstream later on in the digestive process.

What Foods Contain Vitamin B-12?

As already mentioned, vitamin B-12 is found naturally in animal-based foods. It may also be found in other non-animal products that have been fortified with the vitamin. The following is a list of foods that contain vitamin B-12 naturally (2):

  • Fish and shellfish
  • Liver 
  • Red meat
  • Poultry 
  • Eggs
  • Dairy products (milk, cheese, yogurt)

You will also find it in enriched nutritional yeast, fortified breakfast cereals, and enriched soy or rice milk. It can be found in small amounts in nori, however, it depends on where the seaweed came from among other factors.

How Much Do You Need?

The amount of daily dietary vitamin B-12 that you need depends on your age and also your situation. In general, adults need about 2.4 micrograms of it each day. Pregnant and lactating women, however, will need more. Adequate vitamin B-12 status in pregnant and lactating women is crucial to the cognitive development of the growing fetus and baby. Older adults will also need to monitor their status of the vitamin as stomach acid tends to decrease with age. Lower stomach acid makes it harder for the vitamin to be absorbed into the bloodstream.

Read: Vitamin D Deficiency Causes Death, New Study Finds

What Causes Deficiency?

Most adults in the United States are not vitamin B-12 deficient. Deficiencies are seen in greater numbers in minority populations and in lower-income populations. Most cases of vitamin B-12 deficiency are caused by intestinal malabsorption. If you are unable to properly absorb the vitamin from the food you eat into your bloodstream, you will be deficient. (3)

Most malabsorption problems can come from low stomach acid or also a lack of the intrinsic factor required for the small intestine to absorb it. The most common reasons for malabsorption problems are:

  • Pernicious anemia (lack of intrinsic factor)
  • Food-bound vitamin B-12 malabsorption disorder
  • Atrophic gastritis (chronic inflammatory disease of the stomach)

Other causes include stomach surgeries, celiac disease, and other small intestine disorders, pancreatic insufficiency, vegan and vegetarian diets, alcoholism, AIDS, and long-term use of acid-reducing drugs.

Most doctors will recommend people who follow a vegan or vegetarian diet take a vitamin B-12 supplement. Without the consumption of meat and other animal products, reaching your vitamin B-12 intake needs is extremely difficult. 

Signs of Vitamin B-12 Deficiency

The body will give you hints if you are lacking in adequate vitamin B-12. The trick is you just need to know what to listen for. These symptoms are often mild and progress gradually, so you must listen carefully. Pale skin, weakness, and fatigue are the big three. Along with these come difficulty focusing or a difficulty participating in your normal activities. Other symptoms when deficiency becomes worse can include (4):

  • Tingling in the hands and/or feet
  • Loss of sensation in the legs, hands, or feet
  • Shortness of breath
  • Rapid heart rate
  • Dizziness
  • Confusion and irritability
  • Depression

In some extreme cases, people can struggle to walk. They may also develop delirium and paranoia and even dementia.

How To Test For It

Diagnosis of vitamin B-12 deficiency is usually done by a blood test, but also occasionally, doctors will perform an endoscopy. If red blood cells are large, the doctors will suspect a B-12 deficiency. From there, what the doctors decide to do or look for next depends on your age, biological sex, and health status.

If you are low, the doctors will suggest some dietary changes and likely supplementation. In the case of those who lack the intrinsic factor to absorb the vitamin, they may require you to have vitamin B-12 injections. Vitamin B-12 is a water-soluble vitamin, meaning that it is very difficult to overdose when taking supplements. This is because your body just gets rid of any excess that it doesn’t need through the urine.

This article originally appeared on The Premier Daily and has been republished here with permission.

Keep Reading: Do Vitamin B12 Supplements Cause Acne, Bone Fractures, and Lung Cancer?


  1. Vitamin B12.” Harvard T Chan School of Public Health. Harvard University. Accessed July 8, 2022.
  2. Vitamin B12.” Office of Dietary Supplements. National Institute of Health. Updated March 9, 2022. Accessed July 08, 2022.
  3. Vitamin B12.” Linus Pauling Institute | Micronutrient Information Center. Oregon State University. Accessed July 08, 2022.
  4. Vitamin B12 Deficiency.” Merck Manuals. Larry E. Johnson, MD, Ph.D. November 2020.