B12 Deficiency: Symptoms, Causes, Treatment (2024)

Vitamin B12 is an essential nutrient that must be obtained through diet or a supplement. Having too little B12 can cause fatigue, anemia, and neurological problems.

Vitamin deficiencies may sometimes go unnoticed, yet they can have a significant effect on our health. Among the more common deficiencies is vitamin B12.

Here’s what vitamin B12 deficiency looks like and what you can do about it.

Vitamin B12, also known as cobalamin, is a water-soluble vitamin that plays a crucial role in various bodily functions. It’s an essential nutrient that the body needs but cannot produce on its own, so it must be obtained through diet or supplements.

Vitamin B12 is primarily involved in the production of red blood cells, the maintenance of a healthy nervous system, and the metabolism of proteins and fats. It also contributes to DNA synthesis and supports brain function.

A deficiency in vitamin B12 can lead to various symptoms, including:

  • Fatigue and weakness: B12 deficiency can cause general fatigue, lack of energy, and muscle weakness.
  • Anemia: Without enough B12, the body may produce larger, irregularly shaped red blood cells, leading to megaloblastic anemia. Approximately 1–2% of anemia in the general population is due to B12 deficiency. Symptoms may include weakness, shortness of breath, and pale skin.
  • Neurological problems: B12 is vital in maintaining a healthy nervous system. Deficiency can lead to symptoms such as numbness or tingling in the hands and feet, difficulty with balance, muscle weakness, memory problems, and depression.
  • Digestive issues: Some individuals with B12 deficiency may experience digestive problems like loss of appetite, diarrhea, or constipation.
  • Tongue inflammation: B12 deficiency can cause inflammation of the tongue (glossitis), leading to a swollen, red, or sore tongue.

First signs of vitamin b12 deficiency

Fatigue and weakness are often among the first symptoms of a B12 deficiency, followed by pale or yellowish skin due to anemia.

Numbness or tingling sensations in the extremities may occur, along with difficulty maintaining balance or coordination. Mood changes, including irritability, depression, or anxiety, can also be early signs of a B12 deficiency.

Here are some of the common causes of a vitamin B12 deficiency:

Inadequate dietary intake

A diet lacking in animal-based foods — which are the primary sources of vitamin B12 — can lead to deficiency.

In vegetarians, research in 2016 reports low B12 among:

  • 62% of pregnant people
  • 25–86% of children
  • 21–41% of adolescents
  • up to 90% of older adults

Intrinsic factor deficiency

Intrinsic factor, a protein needed for B12 absorption, can become deficient due to pernicious anemia.

Research in 2018 has shown that older adults are at high risk of vitamin B12 malabsorption due to the lack of intrinsic factor production. Their symptoms are often misdiagnosed as Alzheimer’s disease and other chronic conditions.

Gastrointestinal conditions

Conditions like celiac disease, Crohn’s disease, and other gastrointestinal disorders can interfere with the absorption of B12 in the small intestine.

Autoimmune disorders

Autoimmune conditions, such as pernicious anemia or autoimmune gastritis, can result in the destruction of cells that produce intrinsic factor, or damage the stomach lining, affecting B12 absorption.


Certain medications can interfere with B12 absorption, including:

Age-related decline

As we age, the body’s ability to absorb B12 from food decreases, which can contribute to deficiency in older adults.

Alcohol use disorder

Heavy alcohol consumption can lead to poor dietary intake, impaired B12 absorption, and damage to the stomach and small intestine, contributing to deficiency.

If you suspect or have been diagnosed with vitamin B12 deficiency, it’s important to take appropriate steps to address the deficiency and restore your B12 levels.

Here’s what you can do:

  • Consult a healthcare professional: Seek guidance from a healthcare professional who can assess your symptoms, conduct tests to confirm the deficiency, and provide tailored advice based on your specific situation.
  • B12 supplementation: A healthcare professional may recommend B12 supplements, which can be taken orally or administered through injections, depending on the severity of the deficiency. The supplementation will help replenish your B12 levels.
  • Dietary changes: Incorporate foods rich in vitamin B12 into your diet. Animal-based sources such as meat, fish, eggs, and dairy products are excellent sources of B12. If you follow a vegetarian or vegan diet, consider fortified plant-based foods or B12 supplements.
  • Address underlying causes: If your B12 deficiency is caused by an underlying medical condition, such as pernicious anemia or digestive disorders, treating and managing those conditions may be essential for the long-term management of your B12 levels.

Foods with vitamin B12

Vitamin B12 is predominantly found in animal-based foods. Good dietary sources of vitamin B12 include:

  • meat and poultry
  • fish and seafood
  • eggs
  • dairy products
  • fortified foods (cereals, plant-based milk alternatives, nutritional yeast)

Who should take a supplement for vitamin B12?

The following people may benefit from B12 supplementation, but it’s best to reach out to a healthcare professional first:

  • vegetarians and vegans
  • older adults
  • individuals with digestive disorders
  • heavy alcohol users
  • individuals with certain medical conditions or who are taking certain medications

B12 supplements or injections?

Both B12 supplements and injections are effective methods for treating B12 deficiency. The choice between the two depends on the severity of the deficiency, the underlying cause, and individual factors.

B12 supplements, usually taken orally in the form of tablets or capsules, are widely available and convenient. They’re effective for most people with a B12 deficiency, especially those with mild to moderate deficiencies or those who can absorb B12 adequately through the digestive system.

On the other hand, B12 injections bypass the digestive system and deliver the vitamin directly into the muscle or bloodstream. This method is useful for individuals with more severe deficiencies, malabsorption issues, or those who require immediate replenishment of B12 levels.

B12 injections can rapidly increase B12 levels and may be recommended in cases where oral supplementation is ineffective or impractical.

Recovery time from a B12 deficiency varies based on the severity of the deficiency, the underlying cause, and your individual response to treatment.

Improvement in symptoms typically occurs within a few weeks to a few months with appropriate treatment.

Mild deficiencies may resolve relatively quickly through oral B12 supplements or dietary adjustments. However, severe deficiencies or absorption issues may require longer recovery periods, often involving B12 injections or higher-dose oral supplements.

Patience is key, as it can take several months for symptoms to improve and B12 levels to normalize.

Vitamin B12 deficiencies occur when your body doesn’t have enough B12 to function properly. It can lead to various symptoms, including fatigue, weakness, neurological problems, and anemia.

There are several causes of B12 deficiency, such as inadequate dietary intake, intrinsic factor deficiency, gastrointestinal disorders, medications, and age-related decline.

If you suspect you may have B12 deficiency, it’s important to reach out to a healthcare professional so they can test your B12 levels and guide you on a treatment option that works for you.

B12 Deficiency: Symptoms, Causes, Treatment (2024)
Top Articles
Latest Posts
Article information

Author: Chrissy Homenick

Last Updated:

Views: 6533

Rating: 4.3 / 5 (54 voted)

Reviews: 93% of readers found this page helpful

Author information

Name: Chrissy Homenick

Birthday: 2001-10-22

Address: 611 Kuhn Oval, Feltonbury, NY 02783-3818

Phone: +96619177651654

Job: Mining Representative

Hobby: amateur radio, Sculling, Knife making, Gardening, Watching movies, Gunsmithing, Video gaming

Introduction: My name is Chrissy Homenick, I am a tender, funny, determined, tender, glorious, fancy, enthusiastic person who loves writing and wants to share my knowledge and understanding with you.