Beef Liver for B12 Deficiency

A 3-ounce serving of cooked liver supplies 70.7 mcg of B12 (NIH ODS), about 29 times the adult RDA of 2.4 mcg. That makes liver a very good food source. It does not make it a tested treatment: we found no randomised trial of beef liver, in food or capsule form, in anyone with low B12.

The difference matters because B12 deficiency is often an absorption problem. Atrophic gastritis, metformin and acid-suppressing drugs can all reduce how much B12 the gut takes up from food, so adding more B12 to the plate may not move the blood level. The best evidence for fixing a deficiency is for B12 tablets or injections; see the B12 for B12 deficiency page.

Vitamin B12 comes from animal foods, and cooked beef liver supplies far more than the daily requirement in a small serving: 70.7 mcg in 3 ounces against an RDA of 2.4 mcg.

Intake is only half the story. B12 deficiency is usually about getting B12 into the body. ODS lists atrophic gastritis (which lowers intrinsic factor and stomach acid), metformin and proton pump inhibitors among the causes of reduced absorption.

A systematic review of B12 absorption in healthy adults found absorption ranged from 4.5% for a 38 mcg dose from liver to 83% for a 3.0 mcg dose from mutton, and that the amount absorbed rose with dose but less than proportionally (Doets 2013). Those were different foods and studies, so the numbers are not a direct comparison; they show that a large dose is not absorbed in full.

None of those studies were done in people with deficiency, so they cannot say how much liver B12 would reach the blood of someone whose absorption is impaired.

No dose of liver has been tested for B12 deficiency. The B12 deficiency trials tested crystalline B12: 1000 mcg a day orally in two trials and 2000 mcg a day in one, all compared with injections (Cochrane review). A Madrid trial in 283 adults over 65 used 1 mg a day for 8 weeks, then 1 mg a week (Sanz-Cuesta 2020).

Liver capsules vary by product, and no source we read standardises their B12 or vitamin A content. Read the label and count the vitamin A toward your daily limit. The beef liver page has the full form and safety detail.

We searched for trials of beef liver or desiccated liver for B12 status and found none in adults or children with deficiency. The only liver trial linked to this site is a small, unblinded Egyptian study of liver meatballs in 60 children with mild anaemia; it reported anaemia resolving, and the abstract does not report B12 levels (Bassouni 2022).

An Indonesian trial in toddlers tested desiccated liver powder for acceptability only; mothers reported a strong smell and fishy odor as the main objection (Duizer 2017).

In 117 Vietnamese women, a daily animal-source snack providing about 5.5 mcg of B12 eliminated intakes below the average requirement, but serum B12 did not differ from the control group after 6 months (Hall 2017). The snack was not liver and the women were not deficient, so it is context, not proof either way.

The Cochrane review pooled three trials in 153 people; two used 1000 mcg a day orally and found no clinically relevant difference from injections, and one using 2000 mcg a day favoured oral by 680 pg/mL. The authors rated the evidence low quality and noted that no trial reported symptoms. In 283 adults over 65, oral B12 matched injections at 8 weeks, but at 52 weeks 73.6% vs 80.4% had normal levels and non-inferiority was not shown.

A review of 92 older patients with food-cobalamin malabsorption found neurologic and blood abnormalities corrected equally with oral or intramuscular cyanocobalamin (Andrès 2005).

No trial compares liver with a B12 tablet, tests liver capsules, or measures liver's effect in people with pernicious anaemia, atrophic gastritis or metformin use. The NEJM clinical review's abstract concludes that parenteral or high-dose oral B12 is effective therapy, and says nothing about liver.

A 3-ounce serving of liver has 6,582 mcg RAE of vitamin A against an adult upper limit of 3,000 mcg RAE a day, so a single serving is over twice the limit. ODS also states that preformed vitamin A above the limit can cause congenital birth defects.

Add the vitamin A in any multivitamin or capsule. The B12 benefit does not outweigh this for pregnant or conceiving women, who should avoid liver unless a clinician advises otherwise.

Liver adds preformed vitamin A and can interact with products you already take. Metformin and acid reducers matter for B12 itself.