Type

Blood

Part of

Nutritional health

Part of

Nutritional health

Blood biomarker

Part of

Nutritional health

Vitamin B12

Vitamin B12 is vital for red blood cell production and nerve function and the production of DNA. Found in meat, liver, eggs, poultry, shellfish and milk products. It works closely with folic acid.

Vitamin B12

Normal range

180-920 ng/L

Normal range

180-920 ng/L

Normal range

Vitamin B12

Vitamin B12 is vital for red blood cell production and nerve function and the production of DNA. Found in meat, liver, eggs, poultry, shellfish and milk products. It works closely with folic acid.

Vitamin B12

Normal range

180-920 ng/L

Normal range

180-920 ng/L

Normal range

Vitamin B12

Vitamin B12 is vital for red blood cell production and nerve function and the production of DNA. Found in meat, liver, eggs, poultry, shellfish and milk products. It works closely with folic acid.

Vitamin B12

Normal range

180-920 ng/L

Normal range

180-920 ng/L

Normal range

Vitamin B12

Dr. Thiviya Sivakanthan

MBBS

Your Body's Backstage Power Player

Vitamin B12 is your body’s unsung hero - working quietly behind the scenes to support red blood cell production, keep your nerves functioning, and power your energy levels. Without enough B12, your body struggles to make healthy blood, your nervous system falters, and your brain may feel foggy and fatigued. Think of B12 as a protective conductor: it keeps your neurological wiring intact and your body’s essential systems running smoothly. A deficiency can be slow and subtle - but left unchecked, it can lead to serious, irreversible damage.

Get tested

When B12 Levels Drop Too Low

Uncover the early warning signs of deficiency, from tingling hands to brain fog, and how low levels can lead to anaemia and nerve damage.

Why Vitamin B12 Is So Essential

Explore the many roles of B12—from protecting your brain and nerves to supporting DNA production and cardiovascular health.

What Depletes Your Vitamin B12 Stores?

Understand the key causes of B12 deficiency, including diet, ageing, medications, and digestive conditions.

Understanding Your Results

Decode your blood test results and learn when low B12 is just the tip of a deeper nutritional iceberg.

When B12 Levels Drop Too Low

Vitamin B12 deficiency can develop silently. At first, it might just feel like you're running on low battery - tired, mentally foggy, maybe a bit irritable. But over time, the symptoms grow more serious:

Anaemia: Without enough B12, your body can't produce normal red blood cells, leading to fatigue, weakness, and paleness.
Neurological issues: B12 deficiency can damage the protective sheath (myelin) around nerves, causing tingling, numbness, poor balance, or even memory loss and mood changes.
Glossitis and mouth ulcers: You might develop a swollen, painful tongue or sores in your mouth.
Cognitive changes: Brain fog, poor concentration, and low mood are common and sometimes mistaken for depression or ageing.

In severe or prolonged cases, deficiency can lead to irreversible nerve damage, especially in older adults. That’s why early detection and correction are vital.

When B12 Levels Drop Too Low

Anaemia: Without enough B12, your body can't produce normal red blood cells, leading to fatigue, weakness, and paleness.
Neurological issues: B12 deficiency can damage the protective sheath (myelin) around nerves, causing tingling, numbness, poor balance, or even memory loss and mood changes.
Glossitis and mouth ulcers: You might develop a swollen, painful tongue or sores in your mouth.
Cognitive changes: Brain fog, poor concentration, and low mood are common and sometimes mistaken for depression or ageing.

In severe or prolonged cases, deficiency can lead to irreversible nerve damage, especially in older adults. That’s why early detection and correction are vital.

When B12 Levels Drop Too Low

Anaemia: Without enough B12, your body can't produce normal red blood cells, leading to fatigue, weakness, and paleness.
Neurological issues: B12 deficiency can damage the protective sheath (myelin) around nerves, causing tingling, numbness, poor balance, or even memory loss and mood changes.
Glossitis and mouth ulcers: You might develop a swollen, painful tongue or sores in your mouth.
Cognitive changes: Brain fog, poor concentration, and low mood are common and sometimes mistaken for depression or ageing.

In severe or prolonged cases, deficiency can lead to irreversible nerve damage, especially in older adults. That’s why early detection and correction are vital.

Why Vitamin B12 Is So Essential

Vitamin B12 (also known as cobalamin) is a water-soluble vitamin that your body cannot make on its own - it must come from your diet or supplements.

Its roles include:

Red blood cell formation: B12 is essential for making healthy red blood cells that carry oxygen efficiently.
Nervous system protection: It maintains the myelin sheath that insulates nerves, enabling smooth and fast nerve signal transmission.
DNA synthesis: Every time your cells divide, B12 helps ensure accurate replication.
Brain and mood support: B12 is involved in producing neurotransmitters like serotonin and dopamine, which influence your mood and cognitive function.
Heart health: Alongside folate and B6, B12 helps regulate homocysteine, a compound linked to cardiovascular risk when elevated.

Low B12 levels can be especially problematic in older adults, vegetarians/vegans, and people with gastrointestinal issues.

Why Vitamin B12 Is So Essential

Vitamin B12 (also known as cobalamin) is a water-soluble vitamin that your body cannot make on its own - it must come from your diet or supplements.

Its roles include:

Red blood cell formation: B12 is essential for making healthy red blood cells that carry oxygen efficiently.
Nervous system protection: It maintains the myelin sheath that insulates nerves, enabling smooth and fast nerve signal transmission.
DNA synthesis: Every time your cells divide, B12 helps ensure accurate replication.
Brain and mood support: B12 is involved in producing neurotransmitters like serotonin and dopamine, which influence your mood and cognitive function.
Heart health: Alongside folate and B6, B12 helps regulate homocysteine, a compound linked to cardiovascular risk when elevated.

Low B12 levels can be especially problematic in older adults, vegetarians/vegans, and people with gastrointestinal issues.

Why Vitamin B12 Is So Essential

Vitamin B12 (also known as cobalamin) is a water-soluble vitamin that your body cannot make on its own - it must come from your diet or supplements.

Its roles include:

Red blood cell formation: B12 is essential for making healthy red blood cells that carry oxygen efficiently.
Nervous system protection: It maintains the myelin sheath that insulates nerves, enabling smooth and fast nerve signal transmission.
DNA synthesis: Every time your cells divide, B12 helps ensure accurate replication.
Brain and mood support: B12 is involved in producing neurotransmitters like serotonin and dopamine, which influence your mood and cognitive function.
Heart health: Alongside folate and B6, B12 helps regulate homocysteine, a compound linked to cardiovascular risk when elevated.

Low B12 levels can be especially problematic in older adults, vegetarians/vegans, and people with gastrointestinal issues.

What Depletes Your Vitamin B12 Stores?

B12 deficiency isn’t always about poor diet. Here are some of the most common causes:

Inadequate dietary intake: B12 is found mainly in animal products like meat, fish, dairy, and eggs. Vegans are especially at risk and often require supplementation.
Age-related changes: As you age, your stomach produces less acid—needed to absorb B12 from food.
Medications: Long-term use of proton pump inhibitors (PPIs), H2 blockers, and metformin can impair B12 absorption.
Digestive conditions: Pernicious anaemia (an autoimmune condition), coeliac disease, Crohn’s, or history of gastric surgery (like bariatric procedures) all affect absorption.
Alcohol and smoking: Both can reduce your body’s ability to absorb or utilise B12 effectively.

Your liver stores B12 for several years, so deficiency can take time to show up—but once it does, the impact can be significant.

What Depletes Your Vitamin B12 Stores?

B12 deficiency isn’t always about poor diet. Here are some of the most common causes:

Inadequate dietary intake: B12 is found mainly in animal products like meat, fish, dairy, and eggs. Vegans are especially at risk and often require supplementation.
Age-related changes: As you age, your stomach produces less acid—needed to absorb B12 from food.
Medications: Long-term use of proton pump inhibitors (PPIs), H2 blockers, and metformin can impair B12 absorption.
Digestive conditions: Pernicious anaemia (an autoimmune condition), coeliac disease, Crohn’s, or history of gastric surgery (like bariatric procedures) all affect absorption.
Alcohol and smoking: Both can reduce your body’s ability to absorb or utilise B12 effectively.

Your liver stores B12 for several years, so deficiency can take time to show up—but once it does, the impact can be significant.

What Depletes Your Vitamin B12 Stores?

B12 deficiency isn’t always about poor diet. Here are some of the most common causes:

Inadequate dietary intake: B12 is found mainly in animal products like meat, fish, dairy, and eggs. Vegans are especially at risk and often require supplementation.
Age-related changes: As you age, your stomach produces less acid—needed to absorb B12 from food.
Medications: Long-term use of proton pump inhibitors (PPIs), H2 blockers, and metformin can impair B12 absorption.
Digestive conditions: Pernicious anaemia (an autoimmune condition), coeliac disease, Crohn’s, or history of gastric surgery (like bariatric procedures) all affect absorption.
Alcohol and smoking: Both can reduce your body’s ability to absorb or utilise B12 effectively.

Your liver stores B12 for several years, so deficiency can take time to show up—but once it does, the impact can be significant.

Get started

Understanding Your Results

Vitamin B12 is measured via a blood test, typically reported in nanograms per litre (ng/L). It plays a vital role in red blood cell production, nerve function, and DNA synthesis.

Vitamin B12 Normal ranges:

Deficient: < 100 ng/L
Intermediate/Borderline: 100–180 ng/L
Normal: 180–920 ng/L
High: > 920 ng/L

Low or borderline B12 can lead to fatigue, brain fog, nerve tingling, mood changes, or even anaemia if prolonged. But because symptoms can be subtle or overlap with other conditions, further testing may be needed.

Low B12 Treatment Depends on the Cause:

Dietary deficiency: (e.g. vegan or low animal-product intake) Oral supplements like cyanocobalamin or methylcobalamin usually work well.
Absorption issues: (e.g. pernicious anaemia, GI disorders) B12 injections may be necessary long-term.

Important note: Folate and B12 are closely linked in the body. Taking high-dose folic acid can correct the anaemia caused by B12 deficiency while masking its neurological effects—which may become irreversible. Always test both folate and B12 together before starting supplements.

Understanding Your Results

Vitamin B12 is measured via a blood test, typically reported in nanograms per litre (ng/L). It plays a vital role in red blood cell production, nerve function, and DNA synthesis.

Vitamin B12 Normal ranges:

Deficient: < 100 ng/L
Intermediate/Borderline: 100–180 ng/L
Normal: 180–920 ng/L
High: > 920 ng/L

Low B12 Treatment Depends on the Cause:

Dietary deficiency: (e.g. vegan or low animal-product intake) Oral supplements like cyanocobalamin or methylcobalamin usually work well.
Absorption issues: (e.g. pernicious anaemia, GI disorders) B12 injections may be necessary long-term.

Understanding Your Results

Vitamin B12 is measured via a blood test, typically reported in nanograms per litre (ng/L). It plays a vital role in red blood cell production, nerve function, and DNA synthesis.

Vitamin B12 Normal ranges:

Deficient: < 100 ng/L
Intermediate/Borderline: 100–180 ng/L
Normal: 180–920 ng/L
High: > 920 ng/L

Low B12 Treatment Depends on the Cause:

Dietary deficiency: (e.g. vegan or low animal-product intake) Oral supplements like cyanocobalamin or methylcobalamin usually work well.
Absorption issues: (e.g. pernicious anaemia, GI disorders) B12 injections may be necessary long-term.

The Takeaway

Vitamin B12 is critical for your brain, nerves, and blood. A deficiency can leave you tired, foggy, and numb - literally. It often sneaks up slowly, especially in older adults, vegans, or people with digestive issues - but it’s entirely treatable once identified. If you're feeling persistently drained, unsteady on your feet, or mentally off-balance, a B12 test could offer a clear explanation. Don’t ignore the early signs - correcting low B12 now can protect your nerves, sharpen your brain, and restore your energy for years to come.

The Takeaway

References

British Society for Haematology. (2021). Guidelines on the investigation and management of vitamin B12 deficiency.
NHS. Vitamin B12 or folate deficiency anaemia. 2020.
NICE Clinical Knowledge Summaries. Anaemia - B12 and folate deficiency. 2022.
National Institute on Aging. Vitamin B12 Deficiency in Older Adults.

References

British Society for Haematology. (2021). Guidelines on the investigation and management of vitamin B12 deficiency.
NHS. Vitamin B12 or folate deficiency anaemia. 2020.
NICE Clinical Knowledge Summaries. Anaemia - B12 and folate deficiency. 2022.
National Institute on Aging. Vitamin B12 Deficiency in Older Adults.

References

British Society for Haematology. (2021). Guidelines on the investigation and management of vitamin B12 deficiency.
NHS. Vitamin B12 or folate deficiency anaemia. 2020.
NICE Clinical Knowledge Summaries. Anaemia - B12 and folate deficiency. 2022.
National Institute on Aging. Vitamin B12 Deficiency in Older Adults.