Vitamin B12: Unlocking the Mystery

Vit B12 - Deficiency, dietary sources & health implications

B12 deficiency is one of the most common nutrient deficiencies among Indians. (Other common deficiencies being Vit D & Iron deficiency). A research conducted in 2019 revealed that roughly 50% of urban Indians are deficient in this essential nutrient.  B12 deficiency occurs mainly due to our dietary choices. Other reasons are, age-related changes in the body, medical conditions, and the medications we take.

Unlike some other vitamins, our body can’t produce Vitamin B12 on its own, which means we must obtain it through our diet or supplements. Understanding why and how Vitamin B12 deficiency occurs is the first step in safeguarding our health.

Vitamin B12, also known as cobalamin, is a water-soluble vitamin, that belongs to the B-Complex family. It plays a very important role in the human body – from supporting the production of red blood cells, optimizing neurological processes, DNA synthesis, boosting energy levels and nurturing cardiovascular health.

Vitamin B12 has an intricate structure that contains a rare metal element, cobalt, which gives it its name – ‘cobalamin’. This unique composition sets it apart from other vitamins, and it plays a host of vital roles in your body.

Role of Vitamin B12 in the Body

  1. Red Blood Cell Formation: One of the primary functions of Vitamin B12 is its involvement in the production of red blood cells. These cells are crucial for transporting oxygen throughout your body, ensuring your organs and tissues receive the oxygen they need to function optimally. Without adequate B12, your bone marrow struggles to manufacture these essential blood cells, leading to a condition known as anemia. Symptoms of anemia can include fatigue, weakness, and pale skin, all of which can significantly impact your quality of life.
  2. Neurological Health: B12 plays a pivotal role in maintaining the health of your nervous system. It helps protect nerve cells by supporting the formation of the protective myelin sheath, a layer around nerve fibers that facilitates efficient transmission of nerve signals. When myelin is compromised, nerve signals can become slow or disrupted, potentially leading to neurological problems. In severe cases, untreated Vitamin B12 deficiency can result in nerve damage and neurological disorders, which can manifest as numbness, tingling, memory problems, or even mood changes.
  3. Energy Metabolism: Your body needs B12 to convert food into energy. It helps metabolize carbohydrates, fats, and proteins, ensuring that your cells have a constant source of energy to perform their functions. Without sufficient Vitamin B12, the conversion of these nutrients into usable energy can be inefficient, leading to feelings of fatigue and weakness
  4. Methylation Reactions: B12 is involved in a group of biochemical reactions known as methylation. These reactions are critical for DNA synthesis, repair, and regulation, as well as for the metabolism of important molecules like homocysteine.
  5. Immune System Support: Some research suggests that B12 may also play a role in supporting your immune system by helping your body produce immune cells more effectively.
  6. Other Functions: B12 helps regulate homocysteine levels in the blood. Elevated homocysteine is associated with an increased risk of heart disease and stroke. By aiding in the breakdown of homocysteine, Vitamin B12 supports a healthy cardiovascular system.

Also Read: Tips for maintaining kidney health

Difference Between B12 and Other B Vitamins

While Vitamin B12 belongs to the B-complex family, it differs significantly from other B vitamins in several ways:

  • Cobalamin Structure: As previously mentioned, Vitamin B12 contains cobalt, a unique feature not found in other B vitamins.
  • Storage: Unlike some other B vitamins, your body can store Vitamin B12 for an extended period in the liver, which means you don’t need a daily supply.
  • Sources: Vitamin B12 is primarily found in animal-based foods, setting it apart from many other B vitamins that are readily available in both animal and plant sources.

Dietary Sources of Vitamin B12

A. Animal-Based Sources

  1. Meat, Poultry, and Fish: Animal-based foods are the most abundant and reliable sources of B12. Red meat, poultry (such as chicken and turkey), and various types of fish (like salmon, tuna, and trout) are particularly rich in this vitamin. Organ meats, such as liver, are especially potent sources.
  2. Dairy Products: Dairy lovers can rejoice because milk, yogurt, and cheese also contain Vitamin B12. These dairy items provide a convenient source for those who include them in their diet.
  3. Eggs: Eggs are another excellent source of Vitamin B12. Both the yolk and the white of the egg contain this essential nutrient, making them a versatile addition to your diet.

B. Plant-Based Sources

There is no plant source for B12. Vegetarians and vegans have to meet their B12 needs through fortified foods and supplements. Many plant-based milk alternatives, such as almond milk and soy milk, may be fortified with Vitamin B12 to bridge the dietary gap. Certain breakfast cereals may also be fortified. Vitamin B12 supplements are widely available and are a reliable way to ensure you meet your daily needs, especially if you have dietary restrictions or absorption issues.

Recommended Daily Intake for Different Age Groups

The recommended daily intake of Vitamin B12 varies depending on factors such as age, gender, and life stage. Here are general guidelines from the National Institutes of Health (NIH):

  • Infants (0-6 months): 0.4 micrograms (mcg)
  • Infants (7-12 months): 0.5 mcg
  • Children (1-3 years): 0.9 mcg
  • Children (4-8 years): 1.2 mcg
  • Children (9-13 years): 1.8 mcg
  • Adolescents (14-18 years): 2.4 mcg
  • Adults: 2.4 mcg
  • Pregnant and lactating women: 2.6-2.8 mcg

It’s worth noting that these recommendations are general guidelines, and individual needs may vary. Factors like pregnancy, breastfeeding, medical conditions, and medications can influence your B12 requirements

Vitamin B12 – Digestion & Absorption

Dietary Cobalamin (Vitamin B12) that is bound to animal protein is released in the stomach by the action of hydrochloric acid (stomach acid) and an enzyme called pepsin. After being released from food, B12 binds to a protein called R-protein (also known as haptocorrin), which protects it from degradation in the acidic environment of the stomach. In the small intestine, Vitamin B12 is further processed. Pancreatic enzymes digest the R-protein, releasing B12. It then binds to a glycoprotein called intrinsic factor, which is secreted by cells in the stomach lining.

The Vitamin B12-Intrinsic Factor complex travels through the small intestine to the ileum, the final part of the small intestine. Here, there are specialized receptors called cubilin-amnionless receptors on the surface of intestinal cells. The complex binds to these receptors, facilitating the absorption of B12 into the bloodstream. Once absorbed, Vitamin B12 is bound to transport proteins in the blood, primarily transcobalamin II (TC-II). This complex circulates in the bloodstream, delivering B12 to various cells and tissues in the body. Cells in different tissues, particularly the bone marrow for red blood cell production and the nervous system, have specific receptors for the TC-II-bound B12 complex. These receptors allow cells to take up and utilize Vitamin B12 for essential functions.

Who is at Risk of Vitamin B12 Deficiency?

Those who adhere to a strict vegan diet, which excludes all animal products, are at high risk of B12 deficiency. Plant-based diets lack natural sources of B12, making it essential for vegans to rely on fortified foods or supplements. While vegetarians include dairy products and/or eggs in their diet, which can provide some Vitamin B12, they may still be at risk if these foods are not consumed in sufficient quantities or if their absorption is compromised

As individuals age, their ability to absorb B12 from food can diminish. This is often due to reduced stomach acid production, a common age-related change. Additionally, older adults may have a decreased intake of Vitamin B12-rich foods. Regular monitoring of B12 levels is advisable for this demographic.

For some individuals, the delicate balance of stomach acid production can be disrupted. Acid-reducing medications, such as proton pump inhibitors (PPIs) and H2 receptor antagonists, are commonly used to treat conditions like acid reflux, gastroesophageal reflux disease (GERD), and ulcers. While these medications are effective at reducing stomach acid, they can inadvertently lead to B12 deficiency. Prolonged usage of certain Diabetes medications such as Metformin can also lead to B12 deficiency

Conditions that affect the digestive system, such as celiac disease, Crohn’s disease, or atrophic gastritis, can hinder B12 absorption. In some cases, surgery or medications used to treat these conditions can also impact absorption. Autoimmune conditions like Pernicious Anemia damage the stomach lining, reducing intrinsic factor production. As intrinsic factor is crucial for Vitamin B12 absorption, individuals with pernicious anemia often require B12 injections or high-dose oral supplements.

In severe cases, untreated Vitamin B12 deficiency can lead to irreversible nerve damage, making early detection and treatment crucial.

Also Read: Acidity – diet & lifestyle changes

Fermented Food – Is it a reliable source of Vit B12?

The belief that fermented foods are rich in B12 likely stems from the presence of bacteria during the fermentation process. Some of these bacteria are known to produce B12 analogs or compounds that resemble B12. However, these analogs are not biologically active forms of the vitamin and cannot fulfill the body’s B12 requirements.

The fermentation process itself can lead to the degradation of Vitamin B12. Factors such as temperature, acidity, and duration of fermentation can impact the stability of the vitamin. Even within the same batch of fermented food, Vitamin B12 content can vary significantly. This inconsistency makes it challenging to rely on fermented foods as a consistent source of the vitamin

Gut Bacteria & Vit-B12 – Can gut bacteria produce enough Vitamin B12 for the body?

Certain types of gut bacteria can produce B12 (cobalamin) in the human digestive system. However, this production usually occurs in the lower part of the small intestine and the large intestine, where absorption of Vitamin B12 is limited or minimal. Therefore, the B12 produced by gut bacteria in these areas is typically not a significant source of B12 for the body.

The primary site for Vitamin B12 absorption is the ileum, which is the final section of the small intestine. In this region, Vitamin B12 that is derived from dietary sources (animal-based foods) and supplements is efficiently absorbed. However, the B12 produced by gut bacteria in the large intestine is located upstream from the absorption site and is usually not absorbed effectively.

The amount of B12 synthesized by gut bacteria is generally not sufficient to meet the daily requirements of the human body. The production of B12 by gut bacteria is more significant in animals with multi-chambered stomachs, such as cows and sheep, which can then absorb the synthesized B12 in their stomach compartments. Humans have a single-chambered stomach, which limits the absorption of B12 produced by gut bacteria.

Therefore, while gut bacteria do produce B12, it is not a reliable or substantial source of this essential nutrient for humans. Instead, humans primarily obtain B12 from dietary sources like meat, fish, dairy products, eggs, and fortified foods, as well as from supplements when needed

Symptoms of Vit B12 Deficiency

Recognizing the symptoms of Vitamin B12 deficiency is essential for early intervention. Common signs and symptoms include:

  • Fatigue
  • Weakness
  • Anemia (pale skin, shortness of breath)
  • Numbness or tingling in the hands and feet
  • Difficulty walking and balance problems
  • Cognitive changes (memory problems, mood changes)
  • Glossitis (inflamed tongue) and mouth ulcers
  • Vision disturbances

In severe cases, untreated B12 deficiency can lead to irreversible nerve damage, making early detection and treatment crucial.

Also Read: Anemia – Symptoms and Lifestyle changes

Vit B12 – Medical Tests for Deficiency

  1. Blood Tests: Blood tests are the primary method for diagnosing Vitamin B12 deficiency. Two commonly used blood markers are:
    • Serum Vitamin B12 Levels: This measures the amount of Vitamin B12 circulating in your bloodstream. While a low level indicates a deficiency, it’s essential to interpret results in the context of your overall health.
    • Methylmalonic Acid (MMA) Test: Elevated levels of MMA in the blood can indicate Vitamin B12 deficiency. MMA is a compound that accumulates when there isn’t enough Vitamin B12 to metabolize it.
  2. Complete Blood Count (CBC): A CBC can help identify anemia, which is often a symptom of B12 deficiency. It measures the number and quality of red blood cells.
  3. Intrinsic Factor Antibody Test: This test helps diagnose pernicious anemia, an autoimmune condition that impairs intrinsic factor production. If antibodies against intrinsic factor are present, it suggests the condition.
  4. Homocysteine Levels: Elevated homocysteine levels in the blood may indicate a deficiency of B12 (and other B vitamins). High homocysteine levels are associated with an increased risk of heart disease.

Also Read: Gut Bacteria & its role in digestion

Vitamin B12 – Special Considerations

Vitamin B12 and Pregnancy

  1. Fetal Development: Vitamin B12 is essential for the development of the fetal nervous system. Insufficient B12 during pregnancy can lead to developmental issues and neurological problems in the baby.
  2. Preventing Anemia: Pregnant women are already at an increased risk of anemia due to the higher demands for red blood cells. A deficiency in Vitamin B12 can exacerbate this risk, leading to a type of anemia known as megaloblastic anemia.
  3. Recommended Intake: The recommended daily intake of B12 is slightly higher during pregnancy, typically around 2.6-2.8 micrograms (mcg) per day. It’s essential for expectant mothers to meet this requirement through diet or supplements.

Vitamin B12 Supplements and Interactions with Medications

  1. Medications: Some medications can interfere with B12 absorption or utilization. Notable examples include certain antacids, proton pump inhibitors (PPIs), and metformin (used for diabetes). If you’re taking these medications regularly, consult with your healthcare provider to assess your B12 status and consider supplementation if needed.
  2. Medical Conditions: Individuals with gastrointestinal disorders, such as celiac disease or Crohn’s disease, may have impaired absorption of Vitamin B12. If you have such a condition, your healthcare provider may recommend B12 supplementation.

The Role of Vitamin B12 in Cognitive Health

Emerging research has shed light on the potential link between B12 and cognitive health, particularly in older adults. While more studies are needed to establish definitive causation, there are notable observations:

  1. Brain Health: B12 is vital for the maintenance of a healthy nervous system, including the brain. Some studies have suggested that B12 deficiency may be associated with cognitive decline and an increased risk of neurodegenerative conditions, such as Alzheimer’s disease.
  2. Memory and Mood: B12 has been linked to memory function and mood regulation. Deficiency may lead to memory problems, mood swings, and even symptoms resembling depression.
  3. Preventive Measures: To support cognitive health, especially as you age, it’s advisable to maintain adequate B12 levels through a balanced diet or supplements. However, further research is needed to fully understand the precise relationship between Vitamin B12 and cognitive function.

Also Read: Aerobic Vs Anaerobic Exercises

About NuvoVivo

NuvoVivo is an online health and fitness company that helps its client manage lifestyle diseases. Our clients join us from across the world to manage acidity or reverse conditions such as diabetes (and its complications), cardiovascular diseases (hypertension, high cholesterol), fatty liver, PCOS, thyroid disorders, IBS etc. We help them reduce their reliance on medications through structured and scientific lifestyle changes that suit their cultural habits and medical conditions. Our team provides a diet plan, exercise plans and the necessary follow-up and support to help them achieve this

Reach for Consultations @

More about NuvoVivo @


  1. National Institutes of Health – Office of Dietary Supplements. (2020). Vitamin B12 Fact Sheet for Health Professionals. Source
  2. Hunt, A., Harrington, D., & Robinson, S. (2014). Vitamin B12 deficiency. BMJ, 349, g5226. Source
  3. Allen, L. H. (2009). How common is vitamin B-12 deficiency? The American Journal of Clinical Nutrition, 89(2), 693S-696S. Source
  4. O’Leary, F., & Samman, S. (2010). Vitamin B12 in health and disease. Nutrients, 2(3), 299-316. Source
  5. Rizzo, G., Laganà, A. S., Rapisarda, A. M. C., La Ferrera, G. M. G., Buscema, M., Rossetti, P., … & Vitale, S. G. (2016). Vitamin B12 among vegetarians: Status, assessment and supplementation. Nutrients, 8(12), 767. Source
  6. Gaby, A. R. (2011). Suboptimal vitamin B12 levels in the elderly. Alternative Medicine Review, 16(3), 188-196. Source
  7. Obeid, R., Fedosov, S. N., Nexo, E., & Herrmann, W. (2015). Cobalamin coenzyme forms are not likely to be superior to cyano‐and hydroxyl‐cobalamin in prevention or treatment of cobalamin deficiency. Molecular Nutrition & Food Research, 59(7), 1364-1372. Source
  8. Miller, J. W., Garrod, M. G., Allen, L. H., Haan, M. N., & Green, R. (2009). Metabolic evidence of vitamin B-12 deficiency, including high homocysteine and methylmalonic acid and low holotranscobalamin, is more pronounced in older adults with elevated plasma folate. The American Journal of Clinical Nutrition, 90(6), 1586-1592. Source
  9. Tangney, C. C., & Tang, Y. (2013). A pilot study of vitamin B12 in the treatment of tiredness. Journal of Alternative and Complementary Medicine, 19(7), 654-657. Source
  10. Reynolds, E. (2006). Vitamin B12, folic acid, and the nervous system. The Lancet Neurology, 5(11), 949-960. Source
  11. American Pregnancy Association. Vitamin B12 during Pregnancy. Source
  12. National Health Service (NHS). (2021). Vitamin B12 or folate deficiency anaemia. Source

This Post Has 2 Comments

  1. Esta Town

    You’ve got a talent for explaining things clearly.

  2. Carl Bauch

    I always appreciate your balanced view on things. This post was no exception.

Leave a Reply

Our Books