Chicken gizzard and liver: lean muscle against a vitamin A load

Liver eaten as food has been tested against anemia in two randomized trials, with different results. In 60 mildly anemic Egyptian children aged 3 to 9, liver meatballs three times a week for 90 days cleared anemia, present in 43 percent at the start, in every child under 6 and in 88 percent of the older ones. The abstract does not say how much liver the meatballs held, and EFSA judges that liver eaten more often than about once a month can push vitamin A above its upper limit, which is 800 micrograms a day for children aged 1 to 3. That trial was small and unblinded, the control group got nothing, and the abstract does not name the animal. In 274 pregnant Indonesian women, crackers made with chicken liver and eggshell left hemoglobin unchanged (12.0 vs 12.3 g/dL). The women ate 2.5 to 3.6 oz (72 to 103 g) a week against the 525 g planned. Between the two organs, the difference that matters is vitamin A. One 22 g chicken liver carries about 618 micrograms RAE by US survey data, and a Korean analysis found thousands of times more vitamin A in liver than in gizzard. Protein is almost equal in that analysis, 17.7 percent in liver and 17.3 in gizzard, and gizzard had the least fat of all parts tested, 0.81 percent against 2.89. The same vitamin A is the reason for caution with liver: twin infants fed chicken liver every day for four months developed vitamin A toxicity, and a study of a single liver meal is read by its authors as support for caution in pregnancy. EFSA sets the upper limit for preformed vitamin A from all sources at 3,000 micrograms a day for adults and 800 for children aged 1 to 3. EFSA and UK advice both tell women who are pregnant or planning a pregnancy not to eat liver or liver products.

How much is actually in it

• Raw chicken liver measured 21,676 ug RE of vitamin A per 3.5 oz (100 g) in a Korean analysis, thousands of times more than gizzard and the other chicken by-products tested. — Raw chicken by-products (liver, gizzard, heart, lung, crop, cecum, duodenum), Korea Evidence D source
  Vitamin A 21,676.18 ug RE/100 g in liver
• Chicken gizzard and liver carry almost the same protein (17.3% vs 17.7%), but gizzard has the least fat of the by-products tested (0.81% vs 2.89% in liver). — Raw chicken by-products, Korea Evidence D source
  Protein 17.26% gizzard vs 17.70% liver; fat 0.81% vs 2.89%
• Among chicken by-products analyzed, liver held the most iron, copper, manganese and zinc, ahead of gizzard. — Raw chicken by-products, Korea Evidence D source
  Liver highest for Fe, Cu, Mn, Zn
• In the UK dataset, raw chicken liver has 9700 ug retinol, 9.2 mg iron, 35 ug vitamin B12 and 995 ug folate per 3.5 oz (100 g). — Liver, chicken, raw, CoFID code 18-411 Evidence E source
  Per 100 g: retinol 9700 ug; iron 9.2 mg; B12 35 ug; folate 995 ug; protein 17.7 g; fat 2.3 g

What a real portion looks like

• One chicken gizzard weighs about 22 g and a cup about 145 g. Gizzard carries 3.16 mg iron per 3.5 oz (100 g), about 0.7 mg per gizzard. — US survey food Gizzard, FNDDS code 25170420 Evidence E source
  1 gizzard 22 g; 1 cup 145 g; iron 3.16 mg/100 g
• One chicken liver weighs about 22 g and carries about 618 ug RAE of vitamin A (2808 ug per 3.5 oz (100 g)). A cup of 4.9 oz (140 g) carries about 3931 ug. — US survey food Liver, chicken, FNDDS code 25110450 Evidence E source
  1 liver 22 g, 617.8 ug RAE; 1 cup 140 g, 3931 ug RAE; 2808 ug RAE/100 g
• EFSA judges that liver or offal eaten once a month or less keeps preformed vitamin A under the upper limit, while more frequent offal can push intake above it. — European populations (EFSA Comprehensive Food Consumption Database) Evidence E source
  Liver, offal and products thereof no more than once per month: UL not expected to be exceeded; higher frequency may exceed it
• Among the few UK women aged 16-49 who ate liver in the national diet survey, liver alone supplied on average about 3,500 micrograms of vitamin A a day, and 7,500 at the 97.5th percentile. — women aged 16-49, UK NDNS, liver consumers (liver with recipes) (n = 25 consumers) Evidence E source
  Vitamin A from liver: mean 3500 ug/day (50 ug/kg bw), 97.5th percentile 7500 ug/day (97 ug/kg bw)

What your body absorbs

• In a trial in non-pregnant women, one liver meal with up to 120,000 IU of vitamin A raised 24-hour exposure to 13-cis retinoic acid metabolites three- to five-fold, which the authors read as support for caution with liver in pregnancy. — Non-pregnant female volunteers, single liver meal (n = not stated in abstract) Evidence B source
  AUC24h of 13-cis and 13-cis-4-oxo retinoic acid up 3-5 fold; all-trans retinoic acid exposure unchanged despite a temporary 2-fold peak

What cooking and storage change

• In a 2017 hotel outbreak in England with 19 campylobacteriosis cases, chicken liver pate was the food most strongly linked to illness, with a crude relative risk of 12.95. — Guests of a Christmas set-menu meal at one hotel, North Yorkshire, England, January 2017 (n = 19) Evidence C source
  Crude RR 12.95 for chicken liver pate, P < 0.001, with dose-response
• For beef liver simmered, the USDA table keeps 55% of vitamin B6, 70% of folate and 75% of vitamin B12, with iron and zinc fully retained. — USDA R6 group Beef Products, LIVER, SIMMERED, W/DRIPPINGS, code 1153 Evidence E source
  Retention: B6 55%, folate 70%, B12 75%, thiamin 80%, iron 100%, zinc 100%

What it does to your health

• In a cluster RCT in 274 pregnant Indonesian women, crackers made with chicken liver and eggshell did not change maternal hemoglobin (12.0 vs 12.3 g/dL) or infant growth, and adherence stayed far below target. — Pregnant women aged 19-35 years, 7-13 weeks gestation, 28 village clusters in Sumedang, Indonesia, followed to 5 months postpartum (n = 274) Evidence B source
  Maternal Hb 12.0 vs 12.3 g/dL; anemia 11.9% vs 11.3%; no effect on growth outcomes; intake 72-103 g/week vs 525 g/week planned
• In an RCT in 60 mildly anemic Egyptian children aged 3-9, fried liver meatballs three times a week for 90 days cleared anemia (43% at baseline) in all children under 6 and in 88% of older ones. — Boys and girls aged 3-9 years, kindergarten and primary school, urban Giza, Egypt; 90 days (n = 60) Evidence B source
  Anemia prevalence 43% at baseline; resolved in 100% of children under 72 months and 88% of those 72 months or older

Safety, limits and interactions

• A meta-analysis of 75 studies (8585 samples) found ochratoxin A in 66% of poultry gizzard samples, the highest share of any meat or offal type, against 2% of cow liver samples. — Meat, edible offal and meat products sampled worldwide, 1975-2022 (n = 8585 samples) Evidence C source
  OTA prevalence 66% in poultry gizzard vs 2% in cow liver; overall 39%
• US upper limits for preformed vitamin A apply to food and supplements alike and rest on liver abnormalities in adults, birth defects, and toxicity in infants and children. — General population, all ages Evidence E source
  —

What people believe that the data does not support

• In Myanmar, mothers of children aged 12-23 months believed liver causes worms and diarrhea, yet trials of improved practices showed chicken liver could still be promoted as a nutrient gap filler. — Children aged 12-23 months (n 106) and their mothers (n 20 in trials of improved practices), Ayeyarwady region, Myanmar (n = 106) Evidence C source
  Belief reported; overcome in trials of improved practices

Who this works differently for

• Twin infants fed 4.2 oz (120 g) of chicken liver homogenate daily for four months (36,000 IU vitamin A) developed vitamin A toxicity with bulging fontanelles and recovered once intake stopped. — Twin female infants, 4 months of daily chicken liver homogenate (n = 2) Evidence C source
  Irritability, vomiting, bulging anterior fontanelles, enlarged ventricles; full recovery after stopping vitamin A sources
• EFSA in 2024 kept the upper limit for preformed vitamin A at 3,000 micrograms RE a day for adults, set to prevent birth defects, and it applies to pregnant and breastfeeding women too. — EU population; adults including women of child-bearing age, pregnant and lactating women Evidence E source
  UL 3000 ug RE/day for adults, from all sources including food; based on a NOAEL for teratogenicity
• EFSA sets lower upper limits for preformed vitamin A in children, 800 micrograms RE a day at ages 1 to 3 and 1,500 at ages 7 to 10. — EU children and adolescents 1-17 years Evidence E source
  UL ug RE/day: 1-3 y 800; 4-6 y 1100; 7-10 y 1500; 11-14 y 2000; 15-17 y 2600
• EFSA advises women who are planning a pregnancy or are pregnant not to eat liver, offal or products made from them, because retinol can harm the embryo. — women planning pregnancy and pregnant women, EU Evidence E source
  General recommendation: do not consume liver, offal or products thereof (SCF 1992, 2002, maintained 2024)
• UK Government advice, as 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, unless advised by a GP. — pregnant women and women planning pregnancy, UK Evidence E source
  Avoid liver, liver products such as pate, and vitamin A supplements including fish liver oil
• According to NIH, total intakes of preformed vitamin A above the upper limit can cause congenital birth defects. — women who are or might be pregnant Evidence E source
  Teratogenic above the UL

What is still unknown

• A scoping review of 77 studies found that adding muscle tissue to single plant-based meals consistently raised iron and zinc absorption, while the effect across a whole diet is less clear. — Human and animal absorption studies up to September 2021 (n = 77 studies) Evidence C source
  Direction only: higher iron and zinc absorption from single meals; unclear over the whole diet

The bottom line

Vitamin A in chicken liver varies widely by source. The UK table gives 9700 micrograms of retinol per 3.5 oz (100 g) raw, and the Korean sample measured 21,676 micrograms RE. The UK table also gives raw chicken liver 9.2 mg iron, 35 micrograms of vitamin B12 and 995 micrograms of folate per 3.5 oz (100 g). A 22 g gizzard carries about 0.7 mg iron. In the Korean analysis liver held the most iron, copper, manganese and zinc of the by-products tested. Vitamin A is the main reason for caution. US upper limits for preformed vitamin A cover food as well as supplements, and rest on liver damage in adults, birth defects and toxicity in infants and children. EFSA in 2024 kept the adult upper limit at 3,000 micrograms RE a day, pregnancy included, with lower limits for children, 800 at ages 1 to 3 and 1,500 at ages 7 to 10. EFSA judges that liver or offal eaten once a month or less keeps intake under that limit, and that more often can push it above. Among 25 UK women aged 16 to 49 who ate liver, liver alone supplied about 3,500 micrograms a day on average. EFSA advises women planning a pregnancy or pregnant not to eat liver, offal or products made from them, and UK advice says the same for liver and liver products such as pate unless a GP advises otherwise. In non-pregnant women, a single meal of liver, indexed as beef liver, with up to 120,000 IU of vitamin A raised 24-hour exposure to 13-cis retinoic acid metabolites three- to five-fold. That is a blood marker, not a birth outcome, and the authors read it as support for caution with liver in pregnancy. Twin infants fed 4.2 oz (120 g) of chicken liver homogenate a day for four months, 36,000 IU of vitamin A daily, developed vitamin A toxicity with bulging fontanelles and recovered once it stopped. Undercooked liver carries Campylobacter. In a 2017 hotel outbreak in England with 19 cases, chicken liver pate had a crude relative risk of 12.95, which the authors put down to incorrectly cooked liver dishes. This page has no evidence card giving a safe cooking temperature for liver or pate, so it cannot tell you when liver is cooked through. For gizzard the concern is a mold toxin. A meta-analysis of 8585 samples found ochratoxin A in 66 percent of poultry gizzards, the highest share of any meat or offal, against 2 percent of cow liver. That counts how often it appears and says nothing about dose or harm. Mothers in Myanmar believed liver gives children worms and diarrhea, and trials of improved practices there found the belief could be overcome. A scoping review of 77 studies found that adding muscle tissue to single plant-based meals steadily raised iron and zinc absorption, with the effect over a whole diet less clear. Gizzard is muscle and liver is not, and we found no study that measured absorption from either one.

Sources

1. gzl-daily-r8-08 · composition analysis
   Regarding the vitamin A, liver had the highest level (21,676.18 µg RE/100g of raw sample). Noticeably, the level of vitamin A in liver was thousands of times greater than those in the other remaining by-products.
   Korean J Food Sci Anim Resour, 2015 · checked 2026-09-29
2. gzl-daily-r8-09 · composition analysis
   The fat content differed significantly (p<0.05) among the by-products examined; heart had the highest level (4.53%), followed by liver (2.89%), cecum (2.55%), duodenum (2.46%), lung (1.9%) and crop (1.81%), while the gizzard had the lowest level (0.81%). ... Protein content widely varied among the by-products; particularly, liver and gizzard had the highest values (17.70% and 17.26%, respectively)
   Korean J Food Sci Anim Resour, 2015 · checked 2026-09-29
3. gzl-daily-r8-10 · composition analysis
   The outcome of our analysis showed that liver had the highest Fe, Cu, Mn and Zn contents.
   Korean J Food Sci Anim Resour, 2015 · checked 2026-09-29
4. gzl-daily-r8-15 · dataset
   CoFID 2021, 18-411 Liver, chicken, raw: Retinol 9700 ug, Iron 9.20 mg, Vitamin B12 35.0 ug, Folate 995 ug, Protein 17.7 g, Fat 2.3 g per 100 g
   CoFID 2021, Public Health England / OGL v3.0 · checked 2026-09-29
5. gzl-daily-r8-13 · dataset
   Gizzard, WWEIA category Liver and organ meats, FNDDS code 25170420, fdc_id 2706165: 1 gizzard 22 g; 1 cup 145 g; 1 oz yields 20 g; Quantity not specified 85 g; Iron, Fe 3.16 MG per 100 g
   USDA FoodData Central, FNDDS survey foods, release 2024-10-31 · checked 2026-09-29
6. gzl-daily-r8-14 · dataset
   Liver, chicken, WWEIA category Liver and organ meats, FNDDS code 25110450, fdc_id 2706154: 1 liver 22 g; 1 cup 140 g; Vitamin A, RAE 2808 UG per 100 g
   USDA FoodData Central, FNDDS survey foods, release 2024-10-31 · checked 2026-09-29
7. gzl-vita-04 · agency risk characterization
   The Panel considers that the UL for preformed vitamin A is not expected to be exceeded in European populations if consumption of ‘liver, offal and products thereof’ is limited to once per month or less. However, a higher frequency of offal consumption, and/or the consumption of high‐dose supplements, may lead to intakes above the UL (Section 3.5.1 and Sections thereof).
   EFSA NDA Panel, Scientific opinion on the tolerable upper intake level for preformed vitamin A and beta-carotene, EFSA Journal 2024;22(6):e8814 · checked 2026-09-29
8. gzl-vita-06 · exposure assessment
   Liver and liver products in the diet constitute a major source of dietary pre-formed RE. || Table 3. Chronic exposure of Vitamin A from Liver (with recipes) in women aged 16 -49 — Consumers 25 · Mean 3500 µg/person/day · 97.5th percentile 7500 µg/person/day · Mean 50 µg/kg bw/day · 97.5th percentile 97 µg/kg bw/day
   Committee on Toxicity (COT), Statement on the effects of excess Vitamin A on maternal health, 2022, para 111 and Table 3 · checked 2026-09-29
9. gzl-daily-r8-03 · pharmacokinetic trial
   The current study in non-pregnant female volunteers showed that a single high vitamin A intake with a liver meal (up to 120,000 IU) exhibited a similar diurnal-like plasma concentration time curve for all-trans RA and its overall exposure remained also unaltered, despite a temporary two-fold increase in peak plasma concentration. Concentrations of 13-cis and 13-cis-4-oxo RA increased several-fold after a liver meal, and exposure (AUC24h) increased three- to five-fold.
   Int J Vitam Nutr Res, 2005 · checked 2026-09-29
10. gzl-daily-r8-04 · outbreak cohort
    Chicken liver pâté was the food item most strongly associated with illness (P < 0.001) with a corresponding high crude relative risk (12.95).
    Epidemiol Infect, 2020 · checked 2026-09-29
11. gzl-daily-r8-16 · dataset
    USDA Table of Nutrient Retention Factors, Release 6 (2007), Retn_Code 1153, Beef Products, LIVER,SIMMERED,W/DRIPPINGS: vitamin_b6 55%, folate_total 70%, vitamin_b12 75%, thiamin 80%, iron 100%, zinc 100%
    USDA Table of Nutrient Retention Factors, Release 6, 2007 · checked 2026-09-29
12. gzl-daily-r8-01 · cluster RCT
    Intervention adherence was low (72-103 gr/week) compared to 525 gr/week (75 gr/day) recommended, with no significant intervention effect on growth outcomes, after adjusting for maternal height, sex, and human milk intake at 5 months. There were no differences between MEC and SWC groups in maternal Hb (mean ± SD) (12.0 ± 1.1 vs. 12.3 ± 1.2 g/dL) and anemia (11.9 vs 11.3%) at 35-36 weeks GA or morbidity.
    BMC Pregnancy Childbirth, 2025 · checked 2026-09-29
13. gzl-daily-r8-02 · RCT
    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. ... 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 2026-09-29
14. gzl-daily-r8-05 · meta-analysis of surveys
    Concerning food type, OTA prevalence was highest in the poultry gizzard (66%) and lowest in the cow liver (2%).
    Food Chem Toxicol, 2023 · checked 2026-09-29
15. gzl-daily-r8-07 · agency fact sheet
    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.
    NIH Office of Dietary Supplements, Vitamin A and Carotenoids Fact Sheet for Health Professionals · checked 2026-09-29
16. gzl-daily-r8-12 · cross-sectional
    Chicken liver, anchovy and roselle leaves were locally available nutrient-dense foods that would fill these nutrient gaps. ... TIP showed that mothers believed liver and vegetables would cause worms and diarrhoea, but these beliefs could be overcome to successfully promote liver consumption.
    Br J Nutr, 2016 · checked 2026-09-29
17. gzl-daily-r8-06 · case series
    Twin female infants were fed 120 gm of chicken liver homogenate daily for four months. They developed irritability, vomiting, and bulging anterior fontanelles. ... The chicken liver homogenate contained 36,000 IU of vitamin A per 120 gm.
    Pediatrics, 1980 · checked 2026-09-29
18. gzl-vita-01 · agency risk assessment (UL)
    The Panel proposes to retain the UL of 3000 μg RE/day for adults, based on a NOAEL for teratogenicity (Section 3.7.1.1). This UL applies to men and women, including women of child‐bearing age, pregnant and lactating women, and post‐menopausal women.
    EFSA NDA Panel, Scientific opinion on the tolerable upper intake level for preformed vitamin A and beta-carotene, EFSA Journal 2024;22(6):e8814 · checked 2026-09-29
19. gzl-vita-02 · agency risk assessment (UL)
    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.
    EFSA NDA Panel, Scientific opinion on the tolerable upper intake level for preformed vitamin A and beta-carotene, EFSA Journal 2024;22(6):e8814 · checked 2026-09-29
20. gzl-vita-03 · agency recommendation
    Since both acute and chronic intakes of preformed vitamin A and the timing of consumption by pregnant women (i.e. during embryogenesis) may be critical for teratogenicity (Section 3.6.1), the Panel maintains the general recommendation for women who are planning to become pregnant or who are pregnant not to consume liver, offal or products thereof (SCF, 1992, 2002).
    EFSA NDA Panel, Scientific opinion on the tolerable upper intake level for preformed vitamin A and beta-carotene, EFSA Journal 2024;22(6):e8814 · checked 2026-09-29
21. gzl-vita-05 · 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, to avoid potential harm to the unborn child.
    Committee on Toxicity (COT), Statement on the effects of excess Vitamin A on maternal health, 2022, para 6 · checked 2026-09-29
22. gzl-vita-07 · agency fact sheet
    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].
    NIH Office of Dietary Supplements, Vitamin A and Carotenoids Fact Sheet for Health Professionals · checked 2026-09-29
23. gzl-daily-r8-11 · scoping review
    The addition of muscle tissue and muscle tissue fractions to single plant-based meals steadily increased absorption of iron and zinc across studies. The efficacy of the meat factor in increasing iron and zinc absorption in the overall diet is less clear.
    Adv Nutr, 2022 · checked 2026-09-29