Introduction

Vitamin B12 is an essential water-soluble vitamin required for red blood cell formation, DNA synthesis, nerve function, and brain health. Deficiency is extremely common, especially among vegetarians, elderly individuals, and people with digestive disorders.

What Is Vitamin B12?

Vitamin B12, also known as cobalamin, is a vital nutrient involved in neurological function and blood formation.

• Methylcobalamin – Active, neurological support
• Cyanocobalamin – Stable, commonly used
• Hydroxocobalamin – Injectable, long-lasting
• Adenosylcobalamin – Cellular energy support

How Vitamin B12 Works in the Body

Vitamin B12 helps convert food into energy, maintains myelin sheath around nerves, and supports healthy red blood cells.

Sources & Absorption

Vitamin B12 Foods

• Animal sources: Meat, fish, eggs, dairy
• Vegetarian sources: None naturally
• Fortified foods: Cereals, plant milk, nutritional yeast

Vitamin B12 Absorption

B12 absorption requires intrinsic factor, a protein produced in the stomach. Poor absorption is common in elderly and people with gut disorders.

Vitamin B12 Deficiency

Symptoms

• Neurological: Numbness, tingling, memory loss
• Psychiatric: Anxiety, depression, brain fog
• Blood-related: Anemia, weakness, pale skin
• Digestive: Loss of appetite, constipation

Causes

• Vegetarian or vegan diet
• Gastritis, IBS, low stomach acid
• Metformin and long-term PPI use

Untreated deficiency can lead to irreversible nerve damage.

Diagnosis & Lab Tests

• Normal range: 200–900 pg/mL
• Serum B12 test
• MMA (Methylmalonic Acid)
• Homocysteine

Treatment & Dosage

• Adults: 500–1500 mcg/day
• Elderly: 1000 mcg/day
• Pregnancy: 250–500 mcg/day
• Children: 5–50 mcg/day

Oral vs Injection: Injections are used for severe deficiency or absorption issues.

Recovery usually takes 4–12 weeks, depending on severity.

Supplements & Forms

• Tablets
• Sublingual tablets
• Injections

Benefits & Uses

• Boosts energy and reduces fatigue
• Supports brain and memory function
• Repairs nerve damage
• Prevents anemia
• Helps anxiety and depression
• Improves hair, skin, and nails

Safety & Side Effects

• Generally very safe
• No known toxicity
• Rare acne or headache
• May interact with metformin and PPIs

Vitamin B12 is safe for long-term use.

Special Populations

• Vegetarians & vegans: Must supplement
• Pregnancy & breastfeeding: Essential for fetal brain development
• Thyroid patients: Commonly deficient
• Diabetes: Metformin users need monitoring

Frequently Asked Questions

Can B12 deficiency cause anxiety?

Yes. Vitamin B12 deficiency affects neurotransmitters and nerve function, often causing anxiety, panic attacks, and mood changes.

Can high B12 be harmful?

No. Vitamin B12 is water-soluble, and excess amounts are excreted through urine.

Best time to take Vitamin B12?

Morning is ideal, as B12 supports energy production and alertness.

Can B12 cause insomnia?

In some people, taking B12 at night may cause alertness. Morning intake is recommended.

Is daily B12 safe?

Yes. Daily supplementation is safe and often necessary for vegetarians and elderly individuals.