HypeCheck
← All Ingredients Vitamin

Last verified: 10 days ago

Vitamin B12

Also known as: cobalamin, cyanocobalamin, methylcobalamin, hydroxocobalamin, adenosylcobalamin

Evidence under review. — Not yet rated

Essential B vitamin that treats deficiency-related anemia and supports nerve and metabolic health.

  • What it does

    Vitamin B12 is an essential water-soluble vitamin your body cannot make on its own. It is critical for red blood cell formation, nerve function, and DNA synthesis — and deficiency causes...

  • Evidence quality

    Evidence base hasn't been formally rated yet. See research below.

  • Clinical dose

    No established dose from provided studies alone; studies used 500–1000 µg daily

  • Found in

    AG1 (Athletic Greens), Thorne Basic Nutrients 2/Day, Nutrilite Double X and 17 more

See full breakdown ↓ Methodology →

What the Science Says

Vitamin B12 is an essential water-soluble vitamin your body cannot make on its own. It is critical for red blood cell formation, nerve function, and DNA synthesis — and deficiency causes megaloblastic anemia, neurological damage, and elevated homocysteine. Clinical trials show all major delivery routes (oral, intranasal, intramuscular, intravenous) effectively restore B12 levels and reverse deficiency anemia, with intramuscular injection producing the strongest reticulocyte response. Higher dietary B12 intake is also associated with lower risk of liver disease progression and death in people with fatty liver disease.

What It Doesn't Do

Won't improve mood or depression on its own — one RCT found B12 had no antidepressant effect compared to placebo. Won't boost cognitive function in healthy, well-nourished teenagers. Not a standalone fertility treatment — the IVF study combined it with omega-3, folate, and vitamin D, so B12 alone gets no credit. Won't replace ibuprofen for post-surgical pain.

Evidence-Based Benefits

Corrects megaloblastic anemia caused by B12 deficiency regardless of whether given by injection, IV, or nasal spray.

Moderate Evidence

Effective at: No established oral dose from provided studies; injection/IV/intranasal used in RCT

Supporting studies (click to view on PubMed):

PMID 42393020

Fortifying everyday foods like salt or flour with B12 significantly raises blood B12 levels in deficient populations.

Moderate Evidence

Effective at: 0.35 ppm in fortified salt; 0.02 mg/kg in fortified flour

Supporting studies (click to view on PubMed):

PMID 42730560 PMID 42400612

Higher dietary B12 intake is linked to lower risk of liver disease progression and death in people with fatty liver disease.

Weak Evidence

Effective at: No established dose from provided studies

Supporting studies (click to view on PubMed):

PMID 42693175

B12 plays a key role in lowering homocysteine, and deficiency — especially with genetic variants — can cause dangerously high levels.

Weak Evidence

Effective at: No established dose from provided studies

Supporting studies (click to view on PubMed):

PMID 42713553

Absorption & Bioavailability

Moderate to Good — varies significantly by route. Intramuscular injection produces the strongest reticulocyte response; intranasal and intravenous routes show comparable hematological recovery. Oral absorption is limited by intrinsic factor availability and may be poor in people with celiac disease, gut disorders, or MTHFR variants.

Red Flags to Watch For

  • People with celiac disease, Crohn's, or gastric surgery may absorb oral B12 poorly and need injections or intranasal forms
  • High-dose B12 supplements are often sold alongside unproven cognitive or energy claims not supported by the clinical evidence here
  • MTHFR gene variants can impair B12 metabolism — standard supplementation may be insufficient without personalized testing
  • B12 deficiency is common in Afghan refugees (25%), Indian women of reproductive age, and vegetarians/vegans — at-risk groups should test levels, not just supplement blindly
  • The IVF study combined B12 with multiple nutrients; attributing fertility benefits to B12 alone is not supported by the data

Products Containing Vitamin B12

See how Vitamin B12 is used in these analyzed products:

AG1 (Athletic Greens)

Supplement

Overhyped

Thorne Basic Nutrients 2/Day

Supplement

Legitimate

Nutrilite Double X

Supplement

Mostly Legit

Jarrow Formulas B-Right®

Supplement

Legitimate

Life Extension Two-Per-Day Multivitamin

Supplement

Legitimate

Vanilla Creme Shake (310 Nutrition)

Supplement

Overhyped

Gruns

Supplement

Overhyped

The Absorption Company Energy

Supplement

Overhyped

310 Chocolate Icing Shake

Supplement

Overhyped

Purolabs Collagen Complex

Supplement

Overhyped

Affiliatesupps

Supplement

Overhyped

Life Extension Mix Capsules

Supplement

Mostly Legit

Vitabiotics Neuromind Plus

Supplement

Mostly Legit

Baby & Me 2 by MegaFood

Supplement

Legitimate

BrainMD Serotonin Mood Support

Supplement

Mostly Legit

New Chapter Every Woman's One Daily Multivitamin

Supplement

Mostly Legit

OLLY Daily Energy

Supplement

Mostly Legit

Garden of Life Raw Organic Meal Powder Vanilla

Mostly Legit

Ritual Essential for Women Prenatal Multivitamin

Supplement

Mostly Legit

Juna Nightcap Sleep Gummies

Supplement

Mostly Legit
View all product reviews →

Frequently Asked Questions

What does Vitamin B12 do?

Essential B vitamin that treats deficiency-related anemia and supports nerve and metabolic health.

What is the effective dose of Vitamin B12?

No established dose from provided studies alone; studies used 500–1000 µg daily

Is Vitamin B12 safe?

People with celiac disease, Crohn's, or gastric surgery may absorb oral B12 poorly and need injections or intranasal forms

What doesn't Vitamin B12 do?

Won't improve mood or depression on its own — one RCT found B12 had no antidepressant effect compared to placebo.

Research Sources

  • PubMed
  • NIH DSLD

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-09-16