Vitamin B12 is an essential nutrient that plays a critical role in energy production, brain health, and red blood cell formation. Despite its importance, vitamin B12 deficiency is more common than many people realize, especially among older adults, vegans, and people with digestive disorders.
Because the body cannot produce vitamin B12 on its own, it must be obtained through diet or supplementation when necessary.
What Is Vitamin B12?
Vitamin B12 (also known as cobalamin) belongs to the family of water-soluble B vitamins. It is essential for:
- Formation of red blood cells
- DNA synthesis
- Proper nerve function
- Prevention of megaloblastic (macrocytic) anemia
- Vitamin B12 works closely with folate (vitamin B9) to support hemoglobin production. For this reason, doctors often test B12 and folate together when anemia is suspected.
Vitamin B12 Benefits for the Body
Adequate vitamin B12 levels support:
- Healthy brain function and memory
- Nervous system protection
- Energy metabolism and reduced fatigue
- Cardiovascular health
- Healthy red blood cell production
Vitamin B12 Deficiency: Signs and Symptoms
Vitamin B12 deficiency develops gradually, sometimes over several years, because the body can store B12 for 2–4 years.
Common vitamin B12 deficiency symptoms include:
- Tingling or numbness in hands and feet
- Difficulty walking or poor balance
- Memory loss and mental confusion
- Anemia and pale skin
- Red, swollen tongue and burning mouth sensation
- Chronic fatigue and weakness
- Dizziness and chest discomfort
- Heart palpitations
- Ringing in the ears (tinnitus)
- Depression or mood changes
What Causes Vitamin B12 Deficiency?
Several factors can interfere with vitamin B12 absorption:
- Aging, which reduces stomach acid production
- Lack of intrinsic factor, required for B12 absorption
- Atrophic gastritis
- Long-term medication use such as:Proton pump inhibitors (PPIs) for more than one year and metformin use for more than four months
- Vegan or vegetarian diets without supplementation
- Stomach or bariatric surgery
- Digestive disorders such as:Crohn’s disease, Celiac disease, Enteritis, Ileum resection.
Who Is at Higher Risk of Vitamin B12 Deficiency?
Adults over 60
Vegans and strict vegetarians
Pregnant and breastfeeding women
People with gastrointestinal disorders
Individuals taking metformin or acid-reducing medications
Best Food Sources of Vitamin B12
Vitamin B12 is naturally found in animal-based foods because it is produced by bacteria in animals’ digestive systems.
Foods High in Vitamin B12
Beef liver
Shellfish (mussels, clams)
Fish (salmon, sardines)
Beef, lamb, poultry
Eggs
Milk, yogurt, cheese
Fortified Vitamin B12 Foods
Fortified breakfast cereals
Fortified nutritional yeast
Plant-Based Sources of Vitamin B12
Plant foods naturally contain very little B12. Nori seaweed contains small amounts, but not enough to meet daily needs.
How Much Vitamin B12 Do You Need Per Day?
Recommended Daily Intake
Adults (14+ years): 2.4 mcg/day
Pregnant women: 2.6 mcg/day
Breastfeeding women: 2.8 mcg/day
Vitamin B12 Content in Common Foods
Beef liver (100 g): 26–58 mcg
Fish (100 g): 3.1 mcg
Beef or lamb (100 g): 1–3 mcg
Chicken (100 g): 1 mcg
Dairy products (100 g): 0.3–2.4 mcg
One egg: 0.5 mcg
Should You Take a Vitamin B12 Supplement?
Vitamin B12 supplements may be necessary for:
Vegans and vegetarians
Older adults
People with absorption issues
Individuals with confirmed deficiency
Always consult a healthcare professional before starting supplementation.
Frequently Asked Questions About Vitamin B12
Can vitamin B12 deficiency cause fatigue?
Yes. Fatigue is one of the most common symptoms due to reduced oxygen delivery to tissues.
How long does it take to develop B12 deficiency?
It may take years, as the body stores vitamin B12.
Is vitamin B12 safe?
Yes. Vitamin B12 is water-soluble, and excess amounts are usually excreted.
Final Thoughts
Vitamin B12 is essential for maintaining energy, mental clarity, and healthy blood cells. Because deficiency often develops silently, regular screening is especially important for at-risk groups.
A balanced diet, awareness of symptoms, and timely supplementation when needed can protect long-term health.
References
https://ods.od.nih.gov/factsheets/vitamin%20B12-HealthProfessional/
https://ods.od.nih.gov/ Vitamin B12 – Consumer
https://www.hsph.harvard.edu/nutritionsource/vitamin-b12/
O’Leary F, Samman S. Vitamin B12 in Health and Disease. Nutrients. 2010; 2(3):299-316. https://doi.org/10.3390/nu2030299
Rizzo G, Laganà AS, Rapisarda AMC, La Ferrera GMG, Buscema M, Rossetti P, Nigro A, Muscia V, Valenti G, Sapia F, Sarpietro G, Zigarelli M, Vitale SG. Vitamin B12 among Vegetarians: Status, Assessment and Supplementation. Nutrients. 2016; 8(12):767. https://doi.org/10.3390/nu8120767
This article is for informational purposes only and is not a substitute for professional medical advice. Always consult your physician or dietitian for advice tailored to your individual needs.