Liver: one meal, three to five times the retinoic acid

Liver is among the richest sources of preformed vitamin A in the food supply, and that is the reason to eat it and the reason to be careful with it. The UK composition table gives 3.5 oz (100 g) of raw liver between 9,700 mcg of retinol for chicken and 18,800 mcg for calf. The upper limit for adults, set by NIH and kept by EFSA in 2024, is 3,000 mcg a day from food and supplements together, pregnancy included, so 3.5 oz (100 g) of any raw liver in that table holds three to six times the adult limit. For young children the limits are far lower: 600 mcg a day up to age 3 by NIH, 800 mcg at 1 to 3 by EFSA. If you are pregnant or planning a pregnancy, the agency advice is direct. UK Government advice, restated by the Committee on Toxicity in 2022, is not to eat liver or liver products such as pate unless a GP advises it, and EFSA advises women planning a pregnancy or pregnant not to eat liver products. NIH states that total preformed vitamin A above the upper limit can cause birth defects of the eye, skull, lungs and heart, as can retinoid medicines such as isotretinoin. The exposure from one meal is measurable: a single liver meal delivering up to 120 000 IU raised 24-hour exposure to two retinoic acid metabolites, the 13-cis forms, three to five times over. That was measured in women who were not pregnant, so it records the exposure and not any harm. EFSA says Europeans are unlikely to exceed the adult limit if liver and offal are eaten once a month or less. Separately, and this does not make liver safer, the published record of vitamin A poisoning is mostly a record of supplements: across 31 reports, capsules or tablets were the source in 21 of them. The commonest sign was high blood calcium, then gut, neurological and liver problems. Case reports have no denominator, so they describe the syndrome and say nothing about how often food causes it.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• The UK composition table gives raw liver 18,800 mcg of retinol per 3.5 oz (100 g) for calf, 17,400 for pig, 17,300 for lamb, 14,200 for ox and 9,700 for chicken. Chicken liver has about half the vitamin A of calf liver. — UK raw liver, CoFID 2021 codes 18-409, 18-411, 18-413, 18-415, 18-417 (n = 5 foods) Evidence E source
  Retinol per 3.5 oz (100 g) raw: calf 18800 mcg, lamb 17300 mcg, pig 17400 mcg, ox 14200 mcg, chicken 9700 mcg
• Per 100 g cooked, the UK table lists 25,200 mcg of retinol in fried calf liver, 22,600 in stewed pig liver and 10,500 in fried chicken liver. Each cooked value is higher per 3.5 oz (100 g) than the raw value for the same animal. — UK cooked liver and liver dishes, CoFID 2021 codes 18-410, 18-412, 18-416, 18-418, 18-494, 19-603, 19-604 (n = 7 foods) Evidence E source
  Retinol per 3.5 oz (100 g) cooked: calf fried 25200 mcg, pig stewed 22600 mcg, lamb fried 19700 mcg, ox stewed 17300 mcg, chicken fried 10500 mcg; liver and bacon 15752 mcg; liver and onions 11959 mcg

What a real portion looks like

• Liver powder made for toddlers was rated acceptable by the mothers of 96 Indonesian children and then largely went unused over a 2-week home trial, because of the smell. — 96 Indonesian children aged 12 to 23 months and their mothers (n = 96) Evidence B source
  Liking scores from mothers never fell below neutral on a 7-point scale, and after home use mothers rated their children's liking at 3.3 to 3.5 on a 5-point scale with no detectable difference from placebo except lower liking for the liver plus meat combination; the disappearance rate of the powders during the home trial was low, with a strong smell and fishy odor named as the main reason

What your body absorbs

• The NIH fact sheet puts absorption of retinol at 75 to 100 percent and of beta-carotene at 10 to 30 percent, as a range from a review rather than a measurement. — — Evidence E source
  The body may absorb up to 75% to 100% of retinol and in most cases 10% to 30% of beta-carotene from foods; preformed vitamin A is highest in liver, fish, eggs and dairy, and cooking and heat treatment can raise the bioavailability of beta-carotene

What cooking and storage change

• By the USDA retention table, fried liver keeps about 95% of its iron, 80% of its B12 and 85% of its folate. Simmered beef liver eaten without its juices keeps only 60% of iron and B12. Served with the drippings, iron stays at 100%. — USDA R6 Retn_Codes 1151 (lamb, veal and game liver, fried), 1152 and 1153 (beef liver, simmered) (n = 3 methods) Evidence E source
  Fried: iron 95%, B12 80%, folate 85% retained; simmered without drippings: iron 60%, B12 60%, folate 65%, potassium 45%; simmered with drippings: iron 100%, B12 75%, folate 70%

What it does to your health

• In a randomized trial in 60 mildly anemic Egyptian children aged 3 to 9, liver meat balls three times a week for 90 days cleared the 43% baseline anemia in all children under 6 and in 88% of the older ones. — Sixty boys and girls aging 3-9 years, mildly anemic, Giza, Egypt (n = 60) Evidence B source
  Fried liver meat balls three times a week for 90 days; mild and moderate anemia 43% at baseline, gone in all children under 72 months and in 88% of those 72 months or older

Safety, limits and interactions

• NIH sets the upper limit for preformed vitamin A, the form in liver, at 3,000 mcg a day for adults, pregnancy included. For children it is 600 mcg up to age 3, 900 mcg at 4 to 8, 1,700 mcg at 9 to 13 and 2,800 mcg at 14 to 18. The limits cover food and supplements together. — infants, children, adolescents and adults by age band, including pregnancy and lactation Evidence E source
  UL for preformed vitamin A: 600 mcg (birth to 3 years), 900 mcg (4-8 years), 1,700 mcg (9-13 years), 2,800 mcg (14-18 years), 3,000 mcg (19 years and older, pregnancy included)
• NIH states that total intakes of preformed vitamin A above the upper limit can cause birth defects of the eye, skull, lungs and heart, as can retinoid medicines such as isotretinoin. Experts advise women who are or might be pregnant not to take vitamin A supplements above 3,000 mcg a day. — women who are or might be pregnant; people using retinoid medicines Evidence E source
  Intakes above the UL and some retinoid drugs (isotretinoin, etretinate) can cause birth defects of eye, skull, lungs and heart
• EFSA in 2024 kept the upper limit for preformed vitamin A at 3,000 mcg a day for adults, pregnancy included, and 800 to 2,600 mcg for children by age. It says Europeans stay below it if liver and offal are eaten once a month or less. Women planning a pregnancy or pregnant are advised not to eat liver products. — European population, including women of child-bearing age, pregnant and lactating women, children Evidence E source
  UL 3000 mcg RE/day for adults including pregnancy; 800 (1-3 y) to 2600 (15-17 y) mcg RE/day for children; liver and offal once a month or less; no liver products before and during pregnancy
• UK Government advice, restated by the Committee on Toxicity in 2022, is that pregnant women and women thinking about having a baby should not eat liver or liver products such as pate, or take vitamin A supplements, unless a GP advises it. — pregnant women and women planning pregnancy, UK Evidence E source
  Do not eat liver or liver products such as pate, or vitamin A supplements including fish liver oil, unless advised by a GP
• NIH says vitamin A supplements commonly hold 3,000 mcg RAE and multivitamins 750 to 1,050 mcg. The upper limit counts retinol from animal foods and supplements together, so a liver meal adds to whatever a supplement already supplies. — people taking vitamin A supplements or multivitamins Evidence E source
  Supplements commonly 3,000 mcg RAE, multivitamins 750 to 1,050 mcg RAE; the UL counts animal foods and retinol supplements together
• One meal of liver raised 24-hour exposure to two retinoic acid metabolites three to five times over, in women who were not pregnant. — non-pregnant female volunteers Evidence B source
  All-trans retinoic acid kept its diurnal profile and its 24-hour exposure was essentially unchanged despite a temporary doubling of the peak concentration; 13-cis and 13-cis-4-oxo retinoic acid rose several-fold in concentration with a three- to five-fold rise in 24-hour exposure; pooling with published data gave a linear relation between mean 24-hour exposure to those two metabolites and vitamin A intake from liver
• Most recorded vitamin A poisonings came from capsules, and the commonest sign was high blood calcium. — 31 studies: 26 case reports, 3 case series, 1 observational and 1 retrospective study (n = 31 studies) Evidence C source
  The source was vitamin A capsules or tablets in 21 of 31 studies (67.7%); the commonest adverse effect was hypercalcemia (29.0%), then gastrointestinal (25.8%), neurological (22.6%), hepatobiliary (22.6%), musculoskeletal (19.4%) and dermatological (16.1%); acute toxicity presented neurologically with headache, double vision and raised intracranial pressure, chronic toxicity with hepatobiliary, musculoskeletal and calcium problems

What people believe that the data does not support

• In 45 women, heme iron bioavailability was 10.3% alone and fell to 7.1% with fish and 4.9% with chicken, while beef, casein, collagen and albumin changed nothing. — 45 women aged 35 to 45, randomly assigned across the three sub-studies; the foods tested were beef, fish, chicken and a heme concentrate, not liver (n = 45) Evidence B source
  Bioavailability from hemoglobin matched heme alone at about 13.0%, while red blood cell concentrate reached 25.0% and concentrate with beef 21.3% (p < 0.05); heme alone gave 10.3% and fell to 7.1% with fish and 4.9% with chicken (p < 0.05) while beef left it unchanged; casein, collagen and albumin had no effect
• Over 8 weeks in 52 iron-deficient women taking an iron supplement, ferritin rose 10.7 ug/L whether lunch contained 4 oz (113 g) of beef or 4 oz (113 g) of a plant imitation, with no difference between them. — 52 non-pregnant females of reproductive age, mean age 24, with serum ferritin below 25 mcg/L; the food tested was beef against a plant imitation, not liver (n = 52) Evidence B source
  Over 8 weeks ferritin rose 10.7 mcg/L, transferrin saturation 5.1%, body iron stores 2.8 mg/kg and hemoglobin 0.5 g/dL while soluble transferrin receptor fell 0.6 mg/L, all significant as main time effects; no treatment-by-time interaction reached significance for any indicator, meaning animal and plant meals performed alike

The bottom line

The vitamin A in liver behaves differently from the vitamin A in a carrot, and the difference runs both ways. The NIH fact sheet for health professionals, which is an expert body summarizing a literature rather than a measurement in anyone, puts absorption of retinol from food at 75 to 100 percent and beta-carotene at 10 to 30 percent in most cases. We have no trial of our own to set beside those ranges. That is the reason liver fills the gap faster than any vegetable, and why the upper intake limit of 3,000 mcg a day for adults exists for the preformed form only. One is easy to get and easy to overdo. The other is hard to get and hard to overdo. Iron is the second reason people are told to eat liver, and the evidence under that advice is thinner than the advice. We have no absorption trial of liver itself. What we have is heme iron studied alongside other foods, where adding fish cut absorption from 10.3 to 7.1 percent and adding chicken cut it to 4.9 percent, while beef left it alone. Purified casein, collagen and albumin did nothing either way. Each of those comparisons rests on about 15 women and a single meal. And over eight weeks, 52 iron-deficient women taking an iron supplement with either 4 oz (113 g) of beef or 4 oz (113 g) of a plant imitation at lunch ended up in the same place. Ferritin, hemoglobin and transferrin saturation all improved with time, and the meat made no difference to any of them. The meat factor is an idea about single-meal chemistry, and it did not show up in either study here. The one trial of liver itself against anemia is from Egypt, in 60 mildly anemic children aged 3 to 9 who ate fried liver meat balls three times a week for 90 days. The anemia found in 43% of them at the start was gone in all children under 6 and in 88% of the older ones. That trial reports anemia and not how much vitamin A the children took in, and at those ages the NIH upper limit is 600 to 1,700 mcg a day depending on age band. The group most often told to eat liver is small children, and there the honest finding is about what happens in a kitchen. Ninety-six Indonesian toddlers were given complementary foods fortified with beef liver powder. Mothers rated the liking fine, never below neutral, and then very little of the powder actually got used over two weeks at home. The reason they gave was the smell. That study measured liking rather than iron status, so it says nothing about whether the powder works, and it is the only thing we have that measures how families actually use liver at home. We have no card on a standard portion, so the figures here are per 3.5 oz (100 g), and they vary with the animal: chicken liver has about half the vitamin A of calf liver. Cooked liver is no lower, and per 3.5 oz (100 g) the UK table lists 25,200 mcg in fried calf liver and 10,500 mcg in fried chicken liver. NIH says vitamin A supplements commonly hold 3,000 mcg and multivitamins 750 to 1,050 mcg, and the upper limit counts those together with liver. If you are pregnant or planning a pregnancy, the agency advice above is not to eat liver at all unless your GP advises it. If you eat liver regularly, or take a supplement containing retinol on top, the arithmetic belongs to your doctor and not to a page.

Sources

1. hf2-lvr-5 · food composition dataset
   CoFID 2021 Retinol (µg) per 100 g: 18-409 Liver, calf, raw 18800 · 18-411 Liver, chicken, raw 9700 · 18-413 Liver, lamb, raw 17300 · 18-415 Liver, ox, raw 14200 · 18-417 Liver, pig, raw 17400
   CoFID 2021 (Public Health England), codes 18-409 to 18-418 and 18-494, liver by species · checked 2026-10-08
2. hf2-lvr-6 · food composition dataset
   CoFID 2021 Retinol (µg) per 100 g: 18-410 Liver, calf, fried in corn oil 25200 · 18-412 Liver, chicken, fried in corn oil 10500 · 18-416 Liver, ox, stewed 17300 · 18-418 Liver, pig, stewed 22600 · 18-494 Liver, lamb, fried in corn oil 19700 · 19-603 Liver and bacon, fried, homemade 15752 · 19-604 Liver and onions, stewed, homemade 11959
   CoFID 2021 (Public Health England), codes 18-409 to 18-418 and 18-494, liver by species · checked 2026-10-08
3. lvr-r2-06 · randomized acceptability trial
   The low disappearance rate of the study powders during the home trial was a concern, with mothers reporting a strong smell and fishy odor as the major reason why children did not like their meals.
   J Food Sci, 2017 · checked 2026-09-22
4. lvr-r2-02 · expert body fact sheet
   The body might absorb up to 75% to 100% of retinol and, in most cases, 10% to 30% of beta-carotene from foods [17,18].
   NIH Office of Dietary Supplements, Vitamin A and Carotenoids fact sheet for health professionals, snapshot 2026-09-21 · checked 2026-09-22
5. hf2-lvr-7 · nutrient retention dataset
   USDA-RETN-R6:1151 LIVER,FRIED (Lamb, Veal, and Game Products): iron_mg 95%, vitamin_b12_ug 80%, folate_total_ug 85%, thiamin_mg 70%, vitamin_b6_mg 60% retained; USDA-RETN-R6:1152 LIVER,SIMMERED,WO/DRIPPINGS (Beef Products): iron_mg 60%, vitamin_b12_ug 60%, folate_total_ug 65%, potassium_mg 45%, niacin_mg 45%; USDA-RETN-R6:1153 LIVER,SIMMERED,W/DRIPPINGS (Beef Products): iron_mg 100%, vitamin_b12_ug 75%, folate_total_ug 70%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, Retn_Codes 1151, 1152, 1153 · checked 2026-10-08
6. hf2-lvr-9 · randomized controlled trial
   Randomised controlled trial consisting of two arms: control group with no supplement and LMB group receiving LMB supplement three times a week for 90 d. ... Sixty boys and girls aging 3-9 years. ... Initial overall prevalence of mild and moderate anaemia was 43 %, which disappeared completely from all children aging < 72 months and from 88 % of children ≥ 72 months after the 90 d dietary intervention with the LMB.
   Public Health Nutr, 2022 · checked 2026-10-08
7. hf2-lvr-1 · agency advice
   The FNB has established ULs for preformed vitamin A that apply to both food and supplement intakes [5]. The FNB based these ULs on the amounts associated with an increased risk of liver abnormalities in men and women, teratogenic effects, and several toxic effects in infants and children. ... Birth to 12 months 600 mcg 600 mcg 1–3 years 600 mcg 600 mcg 4–8 years 900 mcg 900 mcg 9–13 years 1,700 mcg 1,700 mcg 14–18 years 2,800 mcg 2,800 mcg 2,800 mcg 2,800 mcg 19+ years 3,000 mcg 3,000 mcg 3,000 mcg 3,000 mcg
   NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals · checked 2026-10-08
8. hf2-lvr-2 · agency advice
   Total intakes of preformed vitamin A that exceed the UL as well as some retinoid medications used as topical therapies (such as isotretinoin, used to treat severe acne, and etretinate, a treatment for severe psoriasis) can cause congenital birth defects [1]. These birth defects can include malformations of the eye, skull, lungs, and heart [14]. Experts advise women who are or might be pregnant and those who are lactating not to take high doses (more than 3,000 mcg RAE [10,000 IU] daily) of vitamin A supplements [1].
   NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals · checked 2026-10-08
9. hf2-lvr-3 · EFSA scientific opinion
   The Panel proposes to retain the UL for preformed vitamin A of 3000 μg RE/day for adults. This UL applies to men and women, including women of child‐bearing age, pregnant and lactating women and post‐menopausal women. ... These are 2600 μg RE/day for adolescents 15 to 17 years; 2000 μg RE/day for adolescents 11 to 14 years; 1500 μg RE/day for children 7 to 10 years; 1100 μg RE/day; and 800 μg RE/day for children 1 to 3 years. ... Based on available intake data, European populations are unlikely to exceed the UL for preformed vitamin A if consumption of liver, offal and products thereof is limited to once per month or less. Women who are planning to become pregnant or who are pregnant are advised not to consume liver products.
   EFSA NDA Panel, Scientific opinion on the tolerable upper intake level for preformed vitamin A and beta-carotene, EFSA Journal 2024;22:e8814 · checked 2026-10-08
10. hf2-lvr-4 · agency statement
    UK Government dietary advice, as given on the NHS website, recommends that pregnant women, or women thinking about having a baby, should not consume liver or liver products such as pate, or supplements that contain vitamin A, including fish liver oil, unless advised by a GP
    Committee on Toxicity (COT), Statement on the effects of excess Vitamin A on maternal health, 2022, para 6 · checked 2026-10-08
11. hf2-lvr-8 · agency advice
    Amounts of vitamin A in supplements vary widely, but 3,000 mcg RAE (333% of the DV) is common [21]. Multivitamins commonly have somewhat lower amounts, often 750 to 1,050 mcg RAE (83% to 117% of the DV). ... *These ULs apply only to products from animal sources and supplements whose vitamin A comes entirely from retinol or its ester forms, such as retinyl palmitate.
    NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals · checked 2026-10-08
12. lvr-r2-01 · clinical trial
    Metabolism to all-trans RA of vitamin A with liver seems not to be of safety concern. However, the observed increase of plasma concentrations and the dose-dependent increase in exposure to 13-cis and 13-cis-4-oxo RA support the current safety recommendations on vitamin A intake and suggest that women should be cautious regarding their consumption of liver-containing meals during pregnancy.
    Int J Vitam Nutr Res, 2005 · checked 2026-09-22
13. lvr-r2-03 · systematic review of case reports and case series
    The most common adverse effect was hypercalcemia (n = 9, 29.0%), followed by gastrointestinal manifestations (n = 8, 25.8%), neurological manifestations (n = 7, 22.6%), hepatobiliary manifestations (n = 7, 22.6%), musculoskeletal manifestations (n = 6, 19.4%), and dermatological manifestations (n = 5, 16.1%).
    Clin Chim Acta, 2026 · checked 2026-09-22
14. lvr-r2-04 · randomized controlled trial
    Study 2: the bioavailability from heme alone (10.3%) was reduced (p<0.05) when it was blended with fish (7.1%) and chicken (4.9%), however it was unaffected by beef.
    Food Chem, 2016 · checked 2026-09-22
15. lvr-r2-05 · randomized double-blind controlled trial
    Findings suggest that the "meat factor" does not contribute substantially to improvements in iron status in women of reproductive age with iron deficiency when consumed with an iron supplement for 8 wk.
    Am J Clin Nutr, 2025 · checked 2026-09-22