Blood sausage: dense in iron and fat, thin on direct evidence

In a meta-analysis of 13 randomized trials with 910 people, heme iron raised hemoglobin by 1.06 g/dL more than non-heme iron in children with anemia or low iron stores (95% CI 0.34 to 1.78). The certainty is very low, and most trials gave small doses of heme as supplements or fortified food. Other groups showed no difference. None of those trials used blood sausage, which is the heme food this page is about. In 208 anemic Gambian infants given 10 mg of iron a day for 84 days, a heme iron supplement matched ferrous sulfate on hemoglobin and ferritin. Both are trials of iron given as supplements, not evidence for feeding blood sausage to children. The sausage itself is dense in iron and in fat. Per 100 g, the single USDA reference record lists 6.4 mg of iron, 34.5 g of fat with 13.4 g of it saturated, and 1 microgram of vitamin B12, with no second sample to show how brands differ. A thin round slice of about 8 g gives 0.5 mg of iron, and an unspecified 2.1 oz (60 g) serving about 3.8 mg, both recalculated from the 100 g values.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• UK black pudding carries 14.6 g of starch per 3.5 oz (100 g) in the national table, while the US blood sausage record has 1.3 g of carbohydrate, so the British style is bulked with a starchy filler that the table does not name. — UK black pudding, CoFID 2021 code 19-113, versus US blood sausage, FNDDS 2024 fdc 2706173 (n = 8 samples of 6 brands (CoFID); 1 record (USDA)) Evidence E source
  Starch 14.6 g per 3.5 oz (100 g) in UK black pudding; total carbohydrate 1.29 g per 3.5 oz (100 g) in the US record
• Per 100 g, blood sausage in the USDA reference record carries 34.5 g of fat, 13.4 g of it saturated, 6.4 mg of iron and 1 microgram of vitamin B12. — USDA SR Legacy reference record for blood sausage, single record, no sample spread (n = 1 record) Evidence E source
  Fat 34.5 g, saturated fat 13.4 g, iron 6.4 mg, vitamin B12 1 ug per 3.5 oz (100 g)

What a real portion looks like

• A thin round slice of blood sausage weighs about 8 g and gives 0.5 mg of iron, while an unspecified serving of 2.1 oz (60 g) gives about 3.8 mg. — USDA FNDDS portion weights for blood sausage, food code 25220210 (n = 6 portion measures) Evidence E source
  8 g slice 0.5 mg iron; 0.88 oz (25 g) slice 1.6 mg; 2.1 oz (60 g) serving 3.8 mg; 138 g cup 8.8 mg

What your body absorbs

• In a meta-analysis of 13 randomized trials, heme iron raised hemoglobin by 1.06 g/dL more than non-heme iron in children with anemia or low iron stores, with very low certainty. — 13 randomized trials with 910 participants comparing heme iron with non-heme iron, non-hospitalized groups (n = 910) Evidence A source
  MD 1.06 g/dL (95% CI 0.34 to 1.78) in children; no difference in other groups; side effects RR 0.62 (95% CI 0.40 to 0.96)
• In 208 anemic Gambian infants given 10 mg iron daily for 84 days, heme iron did not beat ferrous sulfate on hemoglobin or ferritin but raised serum iron by 48.4% more. — 208 anemic infants aged 6-12 mo, 84 d of daily supplementation with 10 mg elemental iron as HIP or ferrous sulfate (n = 208) Evidence B source
  No difference in hemoglobin or ferritin; serum iron +48.4% (95% CI 15.4% to 91.0%); transferrin saturation +52.3%
• According to NIH, heme iron from meat is absorbed better than non-heme iron and is less affected by other foods in the meal, though calcium may reduce both. — general population, United States Evidence E source
  Iron bioavailability about 14% to 18% from mixed diets with meat versus 5% to 12% from vegetarian diets

What it does to your health

• Laboratory data suggest that in rats fed blood sausage as a high heme diet, a urinary marker of lipid peroxidation rose sharply and tracked the number of precancerous colon lesions. — rats fed control, chicken, beef or blood sausage diets, short-term and long-term carcinogenesis studies Evidence D source
  DHN-MA excretion increased dramatically and paralleled preneoplastic lesions (P < 0.0001)
• In a randomized crossover study in people, adding heme iron to a red meat diet raised urinary DHN-MA 2-fold, a marker proposed for colon cancer risk. — adults on a 60 g/d red meat baseline diet, compared with 120 g/d red meat, heme iron and non-heme iron supplemented diets Evidence B source
  2-fold increase in DHN-MA with heme supplemented diet (P < 0.001); 8-iso-PGF2alpha not raised in humans
• Observational data link processed meat eating to a higher risk of colorectal polyps but not of colorectal adenomas, across 31 studies. — 31 observational studies on meat subtypes and precancerous colorectal lesions (n = 31 studies) Evidence C source
  Polyps RR 1.65 (95% CI 1.05 to 2.61); adenomas RR 1.14 (95% CI 0.93 to 1.41)

Safety, limits and interactions

• In 2011 USDA FSIS recalled about 72 pounds of a tongue and blood sausage because it held hydrolyzed soy protein that the label did not declare, a reminder that the label is the only way to know what is in a given blood sausage. — buyers of one recalled tongue and blood sausage product, California, 2011 Evidence E source
  About 72 pounds recalled because hydrolyzed soy protein was in the product but not on the label
• CDC lists pregnant women, newborns, adults 65 or older and people with weakened immune systems as at higher risk from Listeria, and tells them to eat deli meats, hot dogs and fermented or dry sausages only reheated to 165°F (74°C) or until steaming hot. CDC does not name blood sausage itself. — pregnant women, newborns, adults 65 or older, people with weakened immune systems Evidence E source
  Avoid unheated deli meat, hot dogs and fermented or dry sausages; choose them reheated to 165°F (74°C) or until steaming hot
• An umbrella review of 9 systematic reviews found that listeriosis in pregnancy can lead to miscarriage, preterm birth, stillbirth and newborn infection, and that most cases occur in the third trimester (66%) rather than the first (3%). — pregnant women and newborns up to 4 weeks after birth (n = 9 systematic reviews, 330 studies) Evidence C source
  Listeriosis can cause miscarriage, preterm birth, stillbirth and neonatal infection; 66% of cases in the third trimester versus 3% in the first
• According to NIH ODS, the upper limit for iron is 40 to 45 mg a day for infants, children and teens depending on age, and adults with normal digestion have very little risk of iron overload from food. — infants, children and adolescents; adults with normal intestinal function Evidence E source
  UL 40 to 45 mg/day for infants, children and adolescents, 45 mg/day for adults; very little overload risk from food in adults

What people believe that the data does not support

• No study in our corpus has measured how well people absorb iron from blood sausage itself, and neither the US nor the EU claim register holds an entry for it. — Layers searched on 2026-10-02 for blood sausage, black pudding, morcilla, heme iron and processed meat: USDA composition, CoFID, FNDDS, USDA retention R6, NHANES, 21 CFR 101, EU claim register, ODS, drug interaction layer, PubMed corpus version pubmed:469432 (n = 2 corpus records under the entity name) Evidence E source
  Zero absorption studies on the food, zero US or EU claims, no composition spread, no retention factors, one allergy case report without abstract

The bottom line

According to the NIH fact sheet, heme iron is absorbed better than non-heme iron and is less affected by other foods in the meal, though calcium may reduce both. The sheet puts iron uptake at about 14 to 18 percent from mixed diets with meat and 5 to 12 percent from vegetarian diets, and it says nothing about blood sausage in particular. We found no study that measured how well people absorb iron from the sausage itself. The colon question is open, for specific reasons. Laboratory data from rats fed blood sausage as a high heme diet show a urinary marker of lipid peroxidation, DHN-MA, rising sharply in step with the number of precancerous colon lesions. In the human arm of the same report, a randomized crossover trial, heme iron added as a supplement to a red meat diet doubled urinary DHN-MA. That is a marker proposed for colon cancer risk, measured in people who did not eat blood sausage, and the abstract gives no headcount. Observational data from 31 studies link processed meat to a higher risk of colorectal polyps (RR 1.65, 95% CI 1.05 to 2.61). For colorectal adenomas the link did not reach significance (RR 1.14, 95% CI 0.93 to 1.41), and none of the 31 studies singled out blood sausage. Who should take care rests on agency advice about classes of food, not on studies of blood sausage. CDC names pregnant women, newborns, adults 65 or older and people with weakened immune systems as at higher risk from Listeria. It tells them to eat deli meats, hot dogs and fermented or dry sausages only reheated to 165°F (74°C) or until steaming hot, and it does not name blood sausage. An umbrella review of 9 systematic reviews found that listeriosis in pregnancy can lead to miscarriage, preterm birth, stillbirth and newborn infection. What is in a given sausage is known only from its label. In 2011 USDA FSIS recalled about 72 pounds of a tongue and blood sausage that held soy protein the label did not declare. UK black pudding carries 14.6 g of starch per 3.5 oz (100 g) against 1.3 g of carbohydrate in the US record, so the British style holds a starchy filler that neither table names. Whether that filler contains gluten cannot be told from these data. The one allergy case report filed under the name has no abstract, and we could not read which allergen was involved. For children, NIH ODS sets the upper limit for total iron at 40 to 45 mg a day depending on age, against about 3.8 mg in a 2.1 oz (60 g) serving. We found nothing on the sodium or saturated fat of processed meat in children's diets, and nothing on medicines. Neither the US nor the EU register holds a health claim for blood sausage.

Sources

1. bls-hf2-02 · composition data
   Black pudding, raw, CoFID 19-113 (8 samples, 6 brands): Starch 14.6 g, Carbohydrate 14.8 g, Fat 20.6 g per 100 g · Blood sausage, FNDDS 25220210, fdc_id 2706173: Carbohydrate, by difference 1.29 G per 100 g
   CoFID 2021 (Public Health England), code 19-113 Black pudding, raw; USDA FNDDS 2024-10-31, fdc 2706173 · checked 2026-10-08
2. bls-r8-01 · food composition data
   Blood sausage, FDC 171618 (SR Legacy, Sausages and Luncheon Meats), per 100 g: Total lipid (fat) 34.5 g · Fatty acids, total saturated 13.4 g · Vitamin B-12 1 ug; FNDDS 2706173: Iron, Fe 6.4 MG
   USDA FoodData Central, SR Legacy FDC 171618 and FNDDS 2706173 · checked 2026-10-02
3. bls-r8-02 · portion data
   Blood sausage, FNDDS 25220210, fdc_id 2706173: 1 slice, round (2-1/4" dia x 1/8" thick) 8 g, Iron 0.5 MG · 1 slice, loaf shape 25 g, Iron 1.6 MG · 1 cubic inch 18 g, Iron 1.2 MG · 1 cup, NFS 138 g, Iron 8.8 MG · Quantity not specified 60 g, Iron 3.8 MG
   USDA FNDDS, food code 25220210, FDC 2706173 · checked 2026-10-02
4. bls-r8-04 · meta-analysis of RCTs
   The meta-analysis showed higher hemoglobin increases in children with anemia or low iron stores receiving HI (MD 1.06 g/dL; 95% CI: 0.34; 1.78; CoE: very low). No statistically significant difference between interventions were found for any iron status indicator in the other population subgroups (CoE: very low).
   Eur J Nutr, 2024 · checked 2026-10-02
5. bls-r8-05 · RCT
   The primary end points of hemoglobin and ferritin concentrations both improved by day 84 with no difference between treatments. For the secondary end point of anemia, the prevalence went from 83.7% to 46.2% in the ferrous sulfate group and from 84.6% to 47.1% in the HIP group. Infants who received HIP had higher serum iron concentration (by 48.4%; 95% CI: 15.4%, 91.0%)
   Am J Clin Nutr, 2025 · checked 2026-10-02
6. bls-r8-06 · fact sheet
   Heme iron has higher bioavailability than nonheme iron, and other dietary components have less effect on the bioavailability of heme than nonheme iron [3,4].
   NIH Office of Dietary Supplements, Iron Fact Sheet for Health Professionals · checked 2026-10-02
7. bls-r8-07 · animal study
   we fed rats four different diets (control, chicken, beef, and blood sausage as a high heme diet)...DHN-MA excretion increased dramatically in rats fed high heme diets, and the excretion paralleled the number of preneoplastic lesions in azoxymethane initiated rats (P < 0.0001).
   Cancer Epidemiol Biomarkers Prev, 2006 · checked 2026-10-02
8. bls-r8-08 · randomized crossover trial
   In the human study, the heme supplemented diet resulted in a 2-fold increase in DHN-MA (P < 0.001).
   Cancer Epidemiol Biomarkers Prev, 2006 · checked 2026-10-02
9. bls-r8-09 · meta-analysis of observational studies
   Processed meat consumption was correlated with increased colorectal polyp risk (1.65; 1.05, 2.61) but not colorectal adenoma risk (1.14; 0.93, 1.41).
   Nutr Rev, 2026 · checked 2026-10-02
10. bls-hf2-01 · agency recall notice
    Mattern Sausage, an Orange, Calif., establishment is recalling approximately 72 pounds of tongue and blood sausage because of mislabeling and an undeclared allergen. The product contains hydrolyzed soy protein, which is not declared on the label ... Soy is a known allergen.
    USDA FSIS, California Firm Recalls Tongue and Blood Sausage Product Due to Mislabeling and an Undeclared Allergen, 2011 · checked 2026-10-08
11. bls-hf2-03 · agency guidance
    Listeria infection is rare. But it can be especially harmful for some people. ... Women who are pregnant ... Newborns ... People who are 65 years or older ... People who have a weakened immune system ... Unheated deli meat, cold cuts, hot dogs, and fermented or dry sausages ... Deli meat, cold cuts, hot dogs, and fermented or dry sausages reheated to 165°F or until steaming hot
    CDC, Preventing Listeria Infection (last reviewed 16 January 2025) · checked 2026-10-08
12. bls-hf2-04 · umbrella review
    Compared with the general population, the risk of being diagnosed with listeriosis increases during pregnancy. Listeriosis can lead to miscarriage, spontaneous preterm labour and preterm birth, stillbirth and congenital neonatal infections.
    BJOG, 2022 · checked 2026-10-08
13. bls-hf2-05 · agency fact sheet
    The Tolerable Upper Intake Level for iron is 45 mg for adults, and it ranges from 40 mg to 45 mg for infants, children, and adolescents, depending on age. Adults with normal intestinal function have very little risk of iron overload from dietary sources of iron [2].
    NIH Office of Dietary Supplements, Iron Fact Sheet for Health Professionals · checked 2026-10-08
14. bls-r8-10 · search record
    blood sausage | black pudding | morcilla | heme iron | processed meat: absorption studies on the food 0 · 21 CFR 101 0 · EU register 0 · CoFID 0 · variability 0 · USDA R6 retention 0 · interaction layer 0 · corpus records under the entity name 2
    Bioma research layers, snapshot 2026-10-02 · checked 2026-10-02