What are the symptoms of vitamin B12 deficiency?

Numbness and tingling of the hands and feet, loss of balance, problems concentrating and, when severe, confusion (MedlinePlus). Long-term deficiency can cause nerve damage that may be permanent if treatment is delayed. A blood test confirms deficiency.

How much vitamin B12 do I need?

The RDA is 2.4 mcg a day for adults, 2.6 mcg in pregnancy and 2.8 mcg while breastfeeding (US National Academies). Doses to treat a diagnosed deficiency are set by a clinician.

Can vitamin B12 help with energy, mood or memory?

In people with normal B12 levels, supplements have not been shown to improve cognitive function or depression (Markun 2021 systematic review). Too few studies of fatigue exist to be sure about energy. If a deficiency is causing symptoms, treating it can help.

Is it possible to take too much vitamin B12?

The US National Academies did not set a tolerable upper intake level for B12 because the evidence was insufficient. That means safety at any dose is not established, so avoid high doses unless a clinician advises them.

Who is at risk of B12 deficiency?

People on a strict vegetarian diet, people with pernicious anemia, Crohn disease or celiac disease, those who have had surgery on the stomach or small intestine, and people who take metformin or antacid and heartburn medicines long-term (MedlinePlus). Older adults should be watched more closely (Miller 2024).

Can folic acid hide a B12 deficiency?

Yes. Folic acid can correct the anemia while nerve damage continues, so the deficiency can go unnoticed. The evidence is mainly correlative (Miller 2024).

Supplement guide Vitamins

Vitamin B12

Vitamin B12 is needed for red blood cells and nerves. See the adult RDA, who is at risk of deficiency, and why supplements have not been shown to improve mood or cognition in people with normal levels.

At a glance

Snapshot

Primary goal: Preventing or treating B12 deficiency
Dosage range: Adult RDA 2.4 mcg a day; doses to treat a deficiency are set by a clinician
Best time to take: Not established in studies
Time to effect: Depends on the cause of deficiency
Common stacks: Not studied
Intake notes: Only about 1% of a large oral dose is absorbed without intrinsic factor. The US National Academies did not set an upper limit because the evidence was insufficient.

Ranked picks

Top 3 Best Vitamin B12 Supplements

#1 NootroScore9.0

NOW Foods

NOW Foods Supplements, Vitamin B-12 5,000 mcg, With Folic Acid, Nervous System Health*, 60 Lozenges

LozengeWith Folic AcidNervous System Health

Quantity: 60 count
Potency: 5,000 mcg

$9.70$0.16/count

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#2 NootroScore9.0

Nature's Bounty

Nature's Bounty Vitamin B12 1000 mcg Supplements, Supports Energy Metabolism, 200 Ct

TabletSupports Energy Metabolism

Quantity: 200 count
Potency: 1000 mcg

$9.48$0.05/count

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#3 NootroScore9.0

Natrol

Natrol Vitamin B12 Fast Dissolve Tablets, Promotes Energy, Supports a Healthy Nervous System, Maximum Strength, Strawberry Flavor, 5,000mcg, 100 Count

TabletFast DissolvePromotes Energy

Quantity: 100 count
Potency: 5,000mcg

$8.96$0.09/count

View product

Top 10 Vitamin B12 Supplements

NOW Foods

NOW Foods Supplements, Vitamin B-12 5,000 mcg, With Folic Acid, Nervous System Health*, 60 Lozenges

LozengeWith Folic AcidNervous System Health

Quantity: 60 count
Potency: 5,000 mcg
NootroScore: 9.0
Price: $9.70$0.16/count

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Nature's Bounty

Nature's Bounty Vitamin B12 1000 mcg Supplements, Supports Energy Metabolism, 200 Ct

TabletSupports Energy Metabolism

Quantity: 200 count
Potency: 1000 mcg
NootroScore: 9.0
Price: $9.48$0.05/count

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Natrol

Natrol Vitamin B12 Fast Dissolve Tablets, Promotes Energy, Supports a Healthy Nervous System, Maximum Strength, Strawberry Flavor, 5,000mcg, 100 Count

TabletFast DissolvePromotes Energy

Quantity: 100 count
Potency: 5,000mcg
NootroScore: 9.0
Price: $8.96$0.09/count

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Nature's Bounty

Nature's Bounty Vitamin B12 2500 mcg, Cellular Energy Support, for Energy Metabolism, Heart & Nervous System Health, 75 Quick Dissolve Tablets

TabletQuick Dissolve

Quantity: 75 count
Potency: 2500 mcg
NootroScore: 9.0
Price: $8.87$0.12/count

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Nature Made

Nature Made Vitamin B12 1000 mcg, Dietary Supplement for Energy Metabolism Support, 150 Softgels, 150 Day Supply

Softgel

Quantity: 150 count
Potency: 1000 mcg
NootroScore: 8.9
Price: $9.98$0.07/count

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vitafusion

vitafusion Extra Strength Vitamin B12 Gummy Vitamins for Energy Metabolism Support and Nervous System Health Support, Cherry Flavored, America’s Number 1 Gummy Vitamin Brand, 45 Day Supply, 90 Count

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Quantity: 90 count
Potency: N/A
NootroScore: 8.9
Price: $9.74$0.11/count

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Nature's Bounty

Nature's Bounty Vitamin B12 5000 Mcg Sublingual Liquid, Cardiovascular Health & Cellular Energy Support, 2 Fl Oz (1 Count)

LiquidCardiovascular HealthCellular Energy Support

Quantity: 2 fl oz
Potency: 5000 mcg
NootroScore: 8.9
Price: $9.99$5/Fl Oz

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Nature Made

Nature Made Vitamin B12 1000 mcg, Dietary Supplement For Energy Metabolism Support, 160 Time Release Tablets, 160 Day Supply

TabletTime ReleaseDietary Supplement For Energy Metabolism Support

Quantity: 160 count
Potency: 1000 mcg
NootroScore: 8.7
Price: $10.65$0.07/count

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Nature Made

Nature Made Extra Strength Vitamin B12 3000 mcg, Dietary Supplement for Energy Metabolism Support, 60 Softgels, 60 Day Supply

Softgel

Quantity: 60 count
Potency: 3000 mcg
NootroScore: 8.5
Price: $11.99$0.20/count

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#10

Dr. Berg

Dr. Berg Natural Vitamin B12 1000 mcg with B Complex Blend - Methylcobalamin B12 for Energy, Nerve Health, and Cognitive Function* - Methylated B12 with Folate - 60 Capsules (2-Month Supply)

CapsuleNaturalMethylcobalamin B12

Quantity: 60 count
Potency: 1000 mcg
NootroScore: 7.1
Price: $19.99$0.33/count

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Use and selection

Buying Guide

Everything you need to know to make an informed decision about Vitamin B12

Why It Matters

B12 is needed for red blood cells and nerves. The groups most at risk of deficiency are people on a strict vegetarian diet, and people with pernicious anemia, Crohn disease or celiac disease, or surgery on the stomach or small intestine. Long-term metformin and long-term antacid or heartburn medicines can reduce absorption.

How Vitamin B12 Helps You

Red blood cells

Low vitamin B12 can cause vitamin B12 deficiency anemia. B12 is needed to form red blood cells.

Nerve health

Long-term deficiency can cause nerve damage, with numbness and tingling in the hands and feet, loss of balance and, when severe, confusion. The damage may be permanent if treatment is delayed.

Mood and cognition

A 2021 systematic review found no overall effect of B12 supplementation on depression, and no evidence of an effect of B12 alone on any cognitive function outcome, in people without advanced neurological disorders.

Energy

Trials in people with normal B12 levels have not shown an energy boost, but too few studies of fatigue exist to be sure.

Frequently Asked Questions

Common questions about Vitamin B12 answered by our experts

What are the symptoms of vitamin B12 deficiency?: Numbness and tingling of the hands and feet, loss of balance, problems concentrating and, when severe, confusion (MedlinePlus). Long-term deficiency can cause nerve damage that may be permanent if treatment is delayed. A blood test confirms deficiency.
How much vitamin B12 do I need?: The RDA is 2.4 mcg a day for adults, 2.6 mcg in pregnancy and 2.8 mcg while breastfeeding (US National Academies). Doses to treat a diagnosed deficiency are set by a clinician.
Can vitamin B12 help with energy, mood or memory?: In people with normal B12 levels, supplements have not been shown to improve cognitive function or depression (Markun 2021 systematic review). Too few studies of fatigue exist to be sure about energy. If a deficiency is causing symptoms, treating it can help.
Is it possible to take too much vitamin B12?: The US National Academies did not set a tolerable upper intake level for B12 because the evidence was insufficient. That means safety at any dose is not established, so avoid high doses unless a clinician advises them.
Who is at risk of B12 deficiency?: People on a strict vegetarian diet, people with pernicious anemia, Crohn disease or celiac disease, those who have had surgery on the stomach or small intestine, and people who take metformin or antacid and heartburn medicines long-term (MedlinePlus). Older adults should be watched more closely (Miller 2024).
Can folic acid hide a B12 deficiency?: Yes. Folic acid can correct the anemia while nerve damage continues, so the deficiency can go unnoticed. The evidence is mainly correlative (Miller 2024).