Vitamin B12
Last updated: August 9, 2026
Benefits
Keeps nerve cells and red blood cells healthy and works with folate to make DNA. Mainly found in animal foods.
How much you need
Recommended daily amounts by life stage, per NIH and NASEM Dietary Reference Intakes. Where the evidence hasn't been enough to set a full RDA (Recommended Dietary Allowance), NASEM sets an AI (Adequate Intake) instead — both are shown together below.
| Life stage | RDA / AI |
|---|---|
| Children 1–3 | 0.9 mcg |
| Children 4–8 | 1.2 mcg |
| Boys 9–13 | 1.8 mcg |
| Girls 9–13 | 1.8 mcg |
| Males 14–18 | 2.4 mcg |
| Females 14–18 | 2.4 mcg |
| Men 19–50 | 2.4 mcg |
| Women 19–50 | 2.4 mcg |
| Men 51–70 | 2.4 mcg |
| Women 51–70 | 2.4 mcg |
| Men 71+ | 2.4 mcg |
| Women 71+ | 2.4 mcg |
| Pregnancy 14–18 | 2.6 mcg |
| Pregnancy 19–50 | 2.6 mcg |
| Lactation 14–18 | 2.8 mcg |
| Lactation 19–50 | 2.8 mcg |
Upper limit
No tolerable upper limit has been established for Vitamin B12. That doesn't mean unlimited amounts are risk-free — it means the evidence NASEM has reviewed so far hasn't been enough to set a numeric ceiling.
Best food sources
| Serving | ||
|---|---|---|
| Clams and shellfish | — | — |
| Beef and liver | — | — |
| Salmon and tuna | — | — |
| Dairy and eggs | — | — |
| Fortified nutritional yeast | — | — |
Absorption & caution
Absorption: Absorption relies on a stomach protein (intrinsic factor) that saturates quickly, so only a small fraction of a large dose is absorbed at once — which is why supplemental amounts often look huge next to the daily reference.
Pairings
Works well with
- Vitamin B9 (Folate) — Vitamin B12 and folate work together in red-blood-cell formation and DNA synthesis. Getting enough B12 matters even when folate intake is high, since high folate can mask the blood signs of a B12 shortfall.
Body systems & goals
Body systems it supports
- Brain — Your brain runs on a steady supply of these nutrients to think, focus, and hold a mood. Keeping them topped up supports the mental clarity that's often the first thing to fade when you're worn down. (established evidence)
- Liver — Your liver is the body's processing hub, handling everything you eat, drink, and metabolize. A balanced spread of these nutrients supports the everyday work it does to keep you steady. (emerging evidence)
Goals it supports
- Energy & stamina (established evidence)
- Healthy aging (established evidence)
- General wellness (established evidence)
- Menopause support (emerging evidence)
- Plant-based diet (established evidence)
- Mood support (emerging evidence)
Frequently asked questions
How much Vitamin B12 do adult women need per day?
Adult women (19–50) need 2.4 mcg of Vitamin B12 per day, per NIH/NASEM Dietary Reference Intakes.
How much Vitamin B12 do adult men need per day?
Adult men (19–50) need 2.4 mcg of Vitamin B12 per day, per NIH/NASEM Dietary Reference Intakes.
Does pregnancy change how much Vitamin B12 you need?
Yes — during pregnancy (ages 19–50) the recommended amount rises to 2.6 mcg per day, compared with 2.4 mcg for non-pregnant adult women.
Is there an upper limit for Vitamin B12?
No tolerable upper limit has been established for Vitamin B12, based on current evidence reviewed by NASEM.
What foods are highest in Vitamin B12?
Good sources include Clams and shellfish, Beef and liver, Salmon and tuna, Dairy and eggs, and Fortified nutritional yeast.
How Tavita handles this
Tavita logs Vitamin B12 from both the food you eat and the supplements you take, adding both into one running daily total. There's no established upper limit for Vitamin B12, so Tavita tracks it against the recommended amount without implying a ceiling that doesn't exist.
Sources
Figures on this page come from the NIH Office of Dietary Supplements fact sheets and the National Academies of Sciences, Engineering, and Medicine (NASEM) Dietary Reference Intake tables — the same dataset that powers the Tavita app. They were independently re-verified by blind re-derivation on August 9, 2026. See the methodology page for how this library is built and kept current.
Tavita is not a medical provider. This page is educational information, not medical advice — talk to your clinician before changing your supplement or medication routine.