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Vitamin B12 Deficiency - One of the Leading Nutrient Deficiencies

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Vitamin B12 Deficiency - One of the Leading Nutrient Deficiencies

4 min read


Vitamin B12 deficiency affects the quality of life of the individuals. Read the article to know more about it.

Medically reviewed by

iCliniq medical review team

Published At January 7, 2017
Reviewed AtMarch 14, 2024


A correctable condition known as vitamin B12 deficiency occurs when there is insufficient intake of vitamin B12 through the diet or when the body fails to absorb it effectively. This deficiency can manifest in physical, neurological, and psychological symptoms. Treatment typically involves administering vitamin B12 medications. This article elaborates on the symptoms and prevention of vitamin B12 deficiency.

What Is Meant by Vitamin B12 Deficiency?

When the body either lacks sufficient intake or struggles to absorb enough vitamin B12 from the food the person consumes, it results in a deficiency. Vitamin B12 is a crucial nutrient essential for the production of red blood cells and DNA, the genetic material found in all cells of the body. Failure to treat vitamin B12 deficiency can lead to physical, psychological, and neurological complications.

What Is the Process by Which the Body Absorbs Vitamin B12?

Two key processes must occur for the absorption of vitamin B12 from the food the person consumes. Initially, hydrochloric acid present in the stomach separates vitamin B12 from the food source. Subsequently, vitamin B12 binds with intrinsic factors, a protein produced by the stomach that facilitates its absorption by the digestive system. Certain individuals experience a rare condition known as pernicious anemia, characterized by the absence of intrinsic factor production in the stomach. Consequently, their bodies are unable to effectively absorb vitamin B12, leading to a deficiency in this essential nutrient.

The recommended daily intake varies based on factors such as age, dietary habits, medical conditions, and medication usage. Here are the average recommended daily amounts in micrograms (mcg) for different age groups:

  • Infants up to 6 months: 0.4 mcg.

  • Babies aged 7-12 months: 0.5 mcg.

  • Children aged 1-3 years: 0.9 mcg.

  • Children aged 4-8 years: 1.2 mcg.

  • Children aged 9-13 years: 1.8 mcg.

  • Teens aged 14-18 years: 2.4 mcg (2.6 mcg per day during pregnancy and 2.8 mcg per day while breastfeeding).

  • Adults: 2.4 mcg (2.6 mcg per day during pregnancy and 2.8 mcg per day while breastfeeding).

What Are the Causes of Vitamin B12 Deficiency?

Vitamin B12 deficiency arises when there is inadequate intake of vitamin B12 through diet or when the body fails to absorb the consumed vitamin B12 effectively. Various situations or conditions that may lead to this deficiency include:

  • Insufficient intake of vitamin B12 in one's diet can lead to deficiency. This occurs when individuals consume insufficient amounts of foods naturally rich in vitamin B12 or fail to include fortified foods in their diet.

  • Gastritis, characterized by inflammation of the stomach lining, is a prevalent factor contributing to vitamin B12 deficiency. This deficiency can result from inadequate hydrochloric acid levels in the stomach, necessary for the proper absorption of vitamin B12.

  • Pernicious anemia, an uncommon medical condition, involves the inability to produce intrinsic factor, a protein synthesized in the stomach. Intrinsic factor is essential for the absorption of vitamin B12. Consequently, individuals with pernicious anemia experience a deficiency in vitamin B12.

  • Digestive disorders such as Crohn’s disease and celiac disease can hinder the complete absorption of vitamin B12 by the body.

  • Individuals who undergo gastrointestinal surgery, such as gastric bypass (a procedure for weight loss), may encounter challenges in absorbing vitamin B12 effectively.

  • Alcohol use disorder can lead to damage to the digestive system, resulting in vitamin B12 deficiency.

  • Transcobalamin II deficiency is a rare genetic disorder that hampers the transportation of vitamin B12, also referred to as cobalamin, throughout the body.

What Are the Signs of a Deficiency in Vitamin B12?

In cases of vitamin B12 deficiency, anemia may develop. While a mild deficiency might not present any noticeable symptoms, untreated deficiency can lead to the following:

  • Weakness, fatigue, or dizziness.

  • Paleness of the skin.

  • Heart palpitations and breathlessness.

  • Gastrointestinal issues such as constipation, loss of appetite, diarrhea, or bloating.

  • Glossitis (smooth tongue).

  • Visual impairment.

  • Neurological symptoms like numbness, muscle weakness, tingling, and difficulty walking.

  • Cognitive issues such as depression, memory impairment, or changes in behavior.

What Are the Food Sources of Vitamin B12?

Vitamin B12 is available in animal-derived foods, where it occurs naturally, or in fortified items. Animal sources encompass dairy products, fish, eggs, poultry, and meat. When seeking foods enriched with B12, refer to the Nutrition Facts label on the product.

What Factors Increase the Risk of Developing a Vitamin B12 Deficiency?

The likelihood of developing vitamin B12 deficiency increases if an individual possesses one or more of the following risk factors:

  • Individuals aged 75 years and older are at an increased risk of developing vitamin B12 deficiency due to potential challenges in the complete absorption of this vitamin by their bodies.

  • Experiencing a digestive system disorder, like celiac disease or Crohn’s disease, can hinder the absorption of vitamin B12 by the body.

  • Adhering to a strict vegan or vegetarian diet increases the risk of vitamin B12 deficiency since this vitamin is exclusively present in animal-derived products like meat and dairy. Consequently, individuals following these dietary patterns are more susceptible to deficiency unless they consume adequate fortified foods containing vitamin B12.

  • The use of specific medications can lead to decreased levels of vitamin B12 in the body. These medications include metformin (used to manage diabetes), histamine H2 blockers (used to reduce stomach acid production), proton pump inhibitors (PPIs, which treat GERD and peptic ulcers), and oral birth control pills (contraceptives).

  • Individuals with Sjögren's syndrome have a significantly higher likelihood of experiencing vitamin B12 deficiency, with a risk over six times greater compared to those without the condition.

  • Excessive alcohol consumption, particularly in cases of chronic alcoholism, can lead to damage to the digestive system and contribute to the development of vitamin B12 deficiency.

What Measures Can Be Taken to Avoid Vitamin B12 Deficiency?

The majority of individuals can avert vitamin B12 deficiency by incorporating foods and beverages rich in vitamin B12 into their diet. Ways to incorporate vitamin B12 into the diet include:

  • Ensure adequate vitamin B12 intake through animal food products like red meat, poultry, fish, eggs, and dairy.

  • Incorporate fortified foods such as certain cereals, plant milk, nutritional yeast, and bread into the diet.

  • Consider vitamin B12 dietary supplements, available in multivitamins or standalone options, after consulting with healthcare providers.

  • Limit alcohol consumption to prevent digestive system damage hindering vitamin B12 absorption. Manage digestive diseases effectively per healthcare provider guidance.


Vitamin B12 is essential for overall health, attainable through dietary intake. Regular consumption can avert deficiency. If at risk or exhibiting symptoms, consult a doctor for a blood test to assess vitamin B12 levels.

Frequently Asked Questions


What Do Low Vitamin B12 Levels Do?

When your body is deficient in vitamin B12, it leads to anemia, nerve damage, problems with memory and thinking, tiredness, and weakness.


What Mainly Causes Vitamin B12 Deficiency?

Conditions causing malabsorption of dietary vitamin B12 like pernicious anemia, aging, absence of a part of the stomach or small intestine (surgically removed), bacterial or parasitic infestation in the small intestine, Crohn’s disease, and celiac disease result in vitamin B12 deficiency. Veganism, alcoholism, and taking certain medicines (Metformin and antacids) also cause B12 deficiency.


What Neurological Symptoms Does B12 Deficiency Cause?

Neurological symptoms caused due to vitamin B12 deficiency include,
- Decreased mental abilities.
- Tingling sensation in fingers and toes.
- Numbness.
- A sensation of imbalance.
- Altered moods or low moods.
- Blurred vision.


How Does a B12 Deficient Tongue Look Like?

Vitamin B12 deficiency causes glossitis, which is the inflammation of the tongue. Tongue in B12 deficiency is swollen, red, painful, and smooth. The tiny taste buds disappear.


Is B12 Deficiency Associated With Weight Gain?

Though vitamin B12 deficiency does not directly cause weight gain, the weakness, fatigue feeling, and tiredness due to B12 deficiency-induced anemia can make one physically less active contributing to weight gain.


How to Promptly Raise Vitamin B12 Levels?

Including the following food items and supplements consistently can help increase B12 levels.
- Beef.
- Chicken.
- Liver.
- Milk.
- Cheese.
- Yogurt.
- Fortified cereals.
- Eggs.
- Fish and shellfish.
- Vitamin B12 supplements.


Which Food Needs to Be Avoided for Vitamin B12 Deficiency?

Alcohol needs to be avoided to prevent the vitamin B12 deficiency. It was found that alcohols tend to reduce B12 levels and provided false test results indicating increased vitamin B12 levels due to alcohol-induced liver disease.


How Long Does It Take for B12 Levels to Become Normal?

Vitamin B12 levels do not surge to normal levels immediately after supplementation or dietary intake. It takes at least six to twelve months for your symptoms to improve.


How Long Do B12 Supplements Take To Work?

Vitamin B12 supplements in the form of injections show immediate results within two to three days of administration. However, supplements are suggested for an extended period to maintain the achieved normal levels and prevent the recurrence of deficiency.


Which Fruit Is Packed With Vitamin B12?

Fruits do not contain vitamin B12. Plant-based foods are not sources of vitamin B12. Instead, fruits, especially citrus ones, contain another B vitamin, folate.


What Medications Should I Not Take Along With B12?

The following drugs decrease the absorption of B12.
- Antacids - Proton pump inhibitors, H2 receptor blockers.
- Antibiotics - Gentamicin, Neomycin, Tobramycin.
- Antidiabetic Drugs - Metformin.
- Anti-Seizure Drugs - Phenytoin, Phenobarbital.
- Colchicine.


Should B12 Injections Be Taken Lifelong?

The root cause for vitamin B12 deficiency decides whether one needs to take B12 injections temporarily or lifelong. Chronic conditions like a surgically removed stomach or small intestine’s part, aging, veganism, being under lifelong medications for diabetes, acidity, etc., need lifelong injections.


Can B12 Correct Nerve Damage Problems?

Vitamin B12 supplements can prevent further progress of nerve damage but are not found to reverse the nerve damage.


Is It Advisable to Take B12 in the Morning or at Night?

It is advisable to take vitamin B12 supplements (tablets) early in the morning with a glass of water on an empty stomach. If you plan to take it at night, it is better to have your dinner early and consume it before your bedtime, to maintain optimal hours’ gap between food and medicine as they are better absorbed in the acidic environment of an empty stomach.
Dr. Prashant Dharmraj Shah
Dr. Prashant Dharmraj Shah



vitamin b12 deficiency
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