Vitamin B12
What is it?
Vitamin B12 (cobalamin) is an essential water-soluble vitamin for red blood cell production, DNA synthesis, neurological function and energy metabolism. It is found exclusively in animal-source foods — meats, eggs, dairy and seafood. Strict vegetarians and vegans have high deficiency risk. Intestinal absorption depends on intrinsic factor produced by the stomach — people with atrophic gastritis or prolonged omeprazole use may have compromised absorption even with adequate intake.
Main Benefits
- Red blood cell production and megaloblastic anemia prevention
- Neurological function and myelin sheath protection
- Energy metabolism — conversion of food into energy
- DNA synthesis and cell division
- Mood and cognitive function support
- Homocysteine reduction (cardiovascular risk factor)
- Skin, hair and nail health
Who it's for
- •Vegans and strict vegetarians (mandatory supplementation)
- •People over 50 (reduced absorption with age)
- •Users of omeprazole and other proton pump inhibitors
- •People with atrophic gastritis or Crohn's disease
- •Individuals with anemia or chronic fatigue
- •People with family history of B12 deficiency
Common Dose
For maintenance: 500–1,000mcg/day orally (passive absorption compensates for low intrinsic factor efficiency at high doses). For severe deficiency: intramuscular injection under medical guidance. Sublingual has superior absorption to conventional oral.
Available Types
Methylcobalamin
Characteristics
- •Active form of B12 — no hepatic conversion required
- •Easily crosses the blood-brain barrier
- •Remains longer in tissues
- •Preferred form for neurological health
Pros
- Active form — immediate bioavailability
- Best for neurological and cognitive health
- No conversion required — ideal for people with MTHFR mutation
Cons
- Higher cost than cyanocobalamin
- Less stable to light — store away from direct light
Best for
- Neurological and cognitive health
- People with MTHFR mutation
- Vegans and vegetarians as first choice
Hydroxocobalamin
Characteristics
- •Natural form of B12 found in food
- •Precursor of methylcobalamin and adenosylcobalamin in the body
- •Longer half-life than cyanocobalamin
- •Used in IM injections in clinical contexts
Pros
- Natural form — converted into both active forms
- Longer half-life
- Preferred for clinical injections
Cons
- Less available in oral supplements
- Requires conversion to active forms
Best for
- Clinical injections for severe deficiency
- Those seeking the form closest to natural
Cyanocobalamin
Characteristics
- •Most common and cheapest synthetic form
- •Requires hepatic conversion to active forms
- •More stable to light and temperature
- •Widely used in supplements and fortified foods
Pros
- Very accessible cost
- High stability
- Effective for most healthy people
Cons
- Requires hepatic conversion
- Contains small amount of cyanide (harmless at normal doses)
- Not ideal for people with MTHFR mutation or liver impairment
Best for
- General use in healthy people
- Those seeking maximum cost-benefit
- Fortified foods
Quick Comparison
| Feature | Methylcobalamin | Hydroxocobalamin | Cyanocobalamin |
|---|---|---|---|
| Form | Active | Natural | Synthetic |
| Conversion required | No | Yes | Yes |
| Neurological action | Superior | Good | Good |
| Stability | Low (light) | Medium | High |
| Cost | Medium | Medium-high | Low |
| Ideal for | Neurology and MTHFR | Clinical injections | General use |
How to Choose
Methylcobalamin
Choose if:
- You are vegan or vegetarian
- You have MTHFR mutation
- You want the active form without hepatic conversion
- The focus is neurological and cognitive health
Hydroxocobalamin
Choose if:
- You need IM injection for severe deficiency
- You want the form closest to the natural form in food
Cyanocobalamin
Choose if:
- You are a healthy person without special conditions
- You seek the best cost-benefit
- You use fortified foods as the main source
What the Science Says
B12 deficiency is one of the most common globally — especially in vegans, elderly and users of metformin or omeprazole. Deficiency can cause megaloblastic anemia, peripheral neuropathy and cognitive decline. Methylcobalamin has specific evidence for nerve regeneration and neuroprotection. Studies show that oral supplementation at high doses (500–1,000mcg) is effective even in people with compromised absorption — passive absorption (without intrinsic factor) compensates.
Possible Side Effects
Extremely safe — excess is excreted in urine as it is water-soluble. Rarely may cause acne at very high doses. Cyanocobalamin contains cyanide in minimal and harmless amounts at normal doses. Allergy is rare but possible.
Final Summary
Vitamin B12 is mandatory for vegans and vegetarians — there is no reliable plant source. For most people, cyanocobalamin works well and is more economical. For those with MTHFR mutation, liver impairment or neurological focus, methylcobalamin is the superior choice. Sublingual surpasses conventional oral in absorption. Test before supplementing in risk groups.