B12 Deficiency: The hidden health issue you might be overlooking

“I just received my check-up results, and my doctor said I have anemia. I’ve been feeling tired for some time now, and it seems like the food I eat doesn’t taste as it used to. Lately, my friends have noticed that I look a bit yellowish. I always thought anemia made you look pale.”

“I had stomach surgery a few years ago, but nobody ever told me that I could develop anemia due to folate deficiency.”

“Because of my Celiac disease, I’ve had to restrict my diet, and now I have anemia. I’ve also been feeling numbness in my legs most of the time. Is this normal?”

“I decided to go vegan five years ago, but now my tongue is red and sore, and I’ve been getting mouth ulcers more frequently.”

A deficiency of vitamin B12 in the blood leads to B12 deficiency, which can progress to anemia. Vitamin B12 is a vital nutrient required for the formation of red blood cells, proper nerve function, and DNA synthesis. When deficient, it can trigger symptoms such as fatigue, weakness, memory problems, and, in more severe cases, nerve damage or anemia. Common causes of this deficiency include inadequate dietary intake—particularly among vegetarians and vegans—malabsorption disorders, or various medical conditions affecting the gastrointestinal system.

 

Symptoms of B12 deficiency

  Fatigue is the most prevalent symptom of B12 deficiency, resulting from a reduction in red blood cell production, which impairs the transport of oxygen throughout the body.

  Weakness often accompanies fatigue, making even routine tasks feel more exhausting.

  Pale or jaundiced skin may develop as a result of impaired red blood cell production and breakdown.

  Numbness or tingling in the hands and feet, known as peripheral neuropathy, can occur, as vitamin B12 is essential for maintaining nerve health.

  Memory problems and difficulty concentrating can arise due to B12’s crucial role in brain function.

  Additional symptoms may include shortness of breath, dizziness, mood changes (such as depression or irritability), and mouth ulcers or a swollen tongue.

  In severe cases, a prolonged deficiency may lead to balance issues and vision disturbances due to nerve damage.

What could influence B12 deficiency

Our bodies absorb vitamin B12 through a specific process when we consume it:

  1. Hydrochloric acid in the stomach breaks vitamin B12 free from the food it is contained in.
  2. Vitamin B12 then binds to a protein called Intrinsic Factor, which is produced by the stomach.

Once bound to intrinsic factor, vitamin B12 can be absorbed by the digestive system. While anyone can develop a vitamin B12 deficiency at any age, individuals over the age of 60 are more likely to become deficient compared to younger age groups.

Vitamin B12 deficiency occurs when you either don’t consume enough vitamin B12 through your diet or your body is unable to absorb it properly. Various situations and conditions can contribute to vitamin B12 deficiency, including:

  1. Inadequate Dietary Intake: People who do not consume sufficient foods that naturally contain vitamin B12 or fail to eat foods fortified with B12 may develop a deficiency.
  2. Gastritis: Gastritis, an inflammation of the stomach lining, is a common cause of B12 deficiency, as it can result in insufficient hydrochloric acid in the stomach.
  3. Pernicious Anaemia: Individuals with pernicious anaemia are unable to produce intrinsic factor, preventing the absorption of B12.
  4. Malabsorption Disorders: Conditions such as celiac disease, Crohn’s disease, or atrophic gastritis can impair nutrient absorption, leading to a B12 deficiency.
  5. Gastrointestinal Surgery: Those who have undergone gastrointestinal surgery, such as bowel resection or gastric bypass, may have difficulty absorbing B12.
  6. Alcoholism: Chronic alcohol consumption can damage the digestive system, interfering with B12 absorption.
  7. Age-Related Changes: Reduced stomach acid production in older adults can impede B12 absorption.
  8. Parasitic Infections: Intestinal parasites, such as tapeworms, can consume B12 before the body has the chance to absorb it.
  9. Genetic Disorders: Rare inherited conditions can affect the body’s ability to process vitamin B12 properly.

 

Daily Requirement of Vitamin B12

The recommended daily intake (RDI) of vitamin B12 varies depending on age, sex, and life stage. For most adults, the RDI is 2.4 micrograms (mcg) per day. However, certain groups may require higher amounts:

  • Pregnant women: 2.6 mcg/day
  • Breastfeeding women: 2.8 mcg/day
  • Older adults: May need supplements due to reduced absorption efficiency.

Vitamin B12 is found in a variety of foods, both of animal origin and in plant-based sources that are fortified with the vitamin.

Animal-Based Sources:

  • Liver (beef or chicken) – One of the richest natural sources of vitamin B12
  • Fish (salmon, tuna, trout, sardines)
  • Shellfish (clams, oysters, crab)
  • Meat (beef, pork, lamb, chicken)
  • Eggs – Particularly the yolk
  • Dairy products – Milk, yogurt, and cheese

Plant-Based & Fortified Sources:

  • Fortified cereals – Clearly labeled as “B12-fortified”
  • Fortified plant-based milks – Such as soy, almond, or oat milk
  • Nutritional yeast – Often fortified with B12
  • B12 supplements – Available in various forms, including tablets, sprays, or injections for those at risk of deficiency

Since natural vitamin B12 is primarily found in animal products, vegetarians and vegans are often advised to rely on fortified foods or supplements to meet their daily B12 needs.

What Happens If I Take Too Much Vitamin B12?

Vitamin B12 is a water-soluble vitamin, meaning that excess amounts are typically excreted through urine, making toxicity a rare occurrence. This often results in bright yellow or neon-colored urine, particularly if you’re taking B12 supplements. However, in cases of extremely high doses—especially from supplements or injections—mild side effects may occasionally occur.

Possible Effects of Excessive B12 Intake:

  • Mild Symptoms: Some individuals may experience headaches, nausea, diarrhea, or skin rashes.
  • Acne or Rosacea Flare-ups: High doses may trigger or exacerbate skin conditions in individuals with sensitivities.
  • Kidney Concerns: In rare instances, very elevated B12 levels could place strain on kidney function, particularly in those with pre-existing kidney issues.

Currently, there is no established Tolerable Upper Intake Level (UL) for vitamin B12, as it is generally regarded as safe. However, it is advisable to adhere to recommended dosages and consult a healthcare professional before taking high-dose supplements.

 

How is B12 deficiency treated?

Vitamin B12 deficiency is typically treated with supplementation, and the choice of treatment method depends on the underlying cause and severity of the deficiency.

Treatment Approaches:

  1. Oral Supplementation:
    • Dosage: High-dose oral vitamin B12 (ranging from 1,000 to 2,000 micrograms daily) is often effective, even for individuals with malabsorption issues.
    • Duration: The length of treatment varies; some individuals may need lifelong supplementation, particularly if the deficiency is caused by irreversible conditions such as pernicious anemia.
  2. Intramuscular Injections:
    • Initial Phase: For severe deficiencies or when rapid correction is necessary, vitamin B12 is administered through intramuscular injections (typically 1,000 micrograms), initially given daily or weekly for several weeks.
    • Maintenance Phase: Once B12 levels are corrected, maintenance injections are typically given on a monthly basis.

The decision to begin vitamin B12 treatment is usually based on the severity of the deficiency and the specific symptoms being experienced.

Future directions: Integrating AI in B12 deficiency management

The University of Adelaide’s 2025 breakthrough optical sensor enables rapid, low-cost B12 quantification in diluted blood samples. This portable device uses fluorescence-based detection to measure B12 concentrations as low as 10 pM, offering a 95% correlation with standard laboratory assays. While not AI-driven itself, this technology lays the groundwork for integration with machine learning algorithms to predict deficiency trajectories or personalize supplementation regimens.

A 2024 study in Scientific Reports demonstrates how explainable AI (XAI) tools—SHAP, LIME, and Qlattice—enhance the differential diagnosis of anemias linked to B12 deficiency. The model’s decision-making process, made interpretable via XAI, allows clinicians to validate predictions against known B12 deficiency biomarkers like hypersegmented neutrophils (indirectly inferred through platelet distribution width). This approach reduces diagnostic delays, particularly in resource-limited settings where advanced testing is unavailable.

Ongoing research aims to combine B12 biomarkers with neuroimaging data in deep learning models. Preliminary studies using 3D convolutional neural networks (CNNs) can predict white matter lesion progression with 89% accuracy by analyzing serial MRI scans and serum B12 trends. Additionally, natural language processing (NLP) tools are being trained on electronic health records to flag early symptom patterns (e.g., paresthesia plus memory complaints) suggestive of preclinical deficiency.

The nexus of B12 deficiency research and AI technology is transforming diagnostic paradigms and therapeutic precision. While current AI applications focus on hematological differentiation and treatment personalization, future innovations promise to integrate genetic, imaging, and clinical data for holistic patient management. Clinicians must remain vigilant to subtle neurological signs, leveraging both biochemical assays and computational tools to mitigate the long-term consequences of B12 insufficiency.

List of References:

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  2. Pernicious Anemia Society. (n.d.). Symptoms of Vitamin B12 Deficiency. Retrieved from: https://www.pernicious-anaemia-society.org/
  3. American Academy of Family Physicians. (2019). Vitamin B12 Deficiency: Causes, Symptoms, and Treatment. American Family Physician, 99(3), 174-182.
  4. Mayo Clinic. (2023). Vitamin B12 Deficiency Symptoms & Causes. Retrieved from: https://www.mayoclinic.org/diseases-conditions/vitamin-b12-deficiency/symptoms-causes/syc-20350498
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