Mackerel and tuna: an oily fish and a lean one

In a Norwegian trial, 232 children aged 4 to 6 ate lunches of herring or mackerel three times a week for 16 weeks, and their red blood cell EPA rose by 0.61 and DHA by 0.43 standard deviations compared with children given meat. Herring and mackerel were pooled, so there is no estimate for mackerel alone. The same lunches raised hair mercury by 0.83 standard deviations (95% CI 0.05 to 1.05), and the abstract gives no absolute level to set against a safety limit. On paper the two fish are barely alike. UK tables give raw mackerel 17.9 g of fat and 4.05 g of omega-3 per 3.5 oz (100 g), against 0.7 g and 0.09 g for raw tuna, as single values with no species or season named. Tuna has more selenium, 93 against 42 mcg. Mercury follows the species more than the name. FDA monitoring found a mean of 0.05 ppm in Atlantic mackerel and 0.126 ppm in canned light tuna, while king mackerel averaged 0.73 ppm and bigeye tuna 0.689 ppm, and the mackerel rows come from reports of 1978 and 2000. We found no study that compared eating mackerel with eating tuna directly.

How much is actually in it

• In 693 samples of Iranian canned tuna the pooled mean histamine was 77.86 mg/kg, below the 200 mg/kg FDA limit cited by the authors. — 11 studies, 693 canned tuna samples, Iran (n = 693 samples) Evidence C source
  Mean 77.86 mg/kg (95% CI 47.51, 108.21), prevalence 9.19% (95% CI 6.88, 11.5)
• FDA monitoring puts mean mercury at 0.05 ppm in Atlantic mackerel and 0.126 ppm in canned light tuna, against 0.689 ppm in bigeye tuna and 0.73 ppm in king mackerel. — FDA and NMFS monitoring samples, US market (n = 80, 545, 21, 213 samples) Evidence E source
  0.05 vs 0.126 vs 0.689 vs 0.73 ppm mean mercury
• Per 100 g raw flesh CoFID lists mackerel at 17.9 g fat, 4.05 g omega-3 and 8.0 ug vitamin D against 0.7 g fat, 0.09 g omega-3 and 3.2 ug vitamin D for tuna, while tuna has more selenium (93 vs 42 ug). — UK composition data, raw flesh Evidence E source
  Fat 17.9 vs 0.7 g, n-3 4.05 vs 0.09 g, vitamin D 8.0 vs 3.2 ug, selenium 42 vs 93 ug, iodine 29 vs 18 ug per 3.5 oz (100 g)

What a real portion looks like

• UK women aged 20 to 39 ate on average 1.2 oz (33 g) of oily fish a week in 2008-2021, 24% of the 140 g NHS target, and the authors name mackerel as a target fish. — UK women aged 20-39, National Diet and Nutrition Survey, 4-day food diaries Evidence C source
  33 g/week oily fish vs 140 g recommended
• In FNDDS a standard can of mackerel weighs 2.6 oz (75 g) and a large can 420 g, while a standard can of tuna weighs 4.1 oz (115 g) and a small can or pouch 75 g. — US dietary survey portion database Evidence E source
  Portion weights in grams

What your body absorbs

• Lunches of fatty fish (herring or mackerel) three times a week for 16 weeks raised red blood cell EPA by 0.61 and DHA by 0.43 standard deviations versus meat in 232 children aged 4 to 6. — 232 children aged 4-6 y from 13 kindergartens, Norway, fatty fish vs meat lunches 3 times a week for 16 weeks (n = 232) Evidence B source
  RBC EPA SMD 0.61 (95% CI 0.36, 0.86), DHA SMD 0.43 (95% CI 0.21, 0.66)
• In 60 toddlers randomized to four formulas for one month, DHA from microencapsulated tuna oil powder gave significantly higher blood DHA than the same tuna oil added as plain oil. — 60 healthy toddlers aged 1-4 y, Malaysia, 4 arms of 15, one month (n = 60) Evidence B source
  Higher blood DHA with microencapsulated powders vs plain high-DHA tuna oil (significant, size not in abstract)

What cooking and storage change

• Anisakid larvae were found in 0.64% of muscle and 0.95% overall of Mediterranean anchovy, pilchard and Atlantic mackerel, fish often eaten raw or lightly preserved. — 12 studies of Mediterranean seafood, 4 on anchovy, pilchard and Atlantic mackerel (n = 12 studies) Evidence C source
  Prevalence 0.64% muscle, 1.34% viscera, 0.95% overall
• FDA guidance says parasites in fish meant to be eaten raw are killed by freezing at -20°C (-4°F) or below for 7 days, or at -35°C (-31°F) until solid and then 15 hours, and that heating fish enough to kill bacteria also kills parasites. — fish intended to be eaten raw or undercooked (US seafood industry guidance) Evidence E source
  -4 °F (-20°C) for 7 days, or -31 °F (-35°C) until solid plus 15 hours at -31 °F (-35°C), or plus 24 hours at -4 °F (-20°C), kills parasites

What it does to your health

• High-DHA tuna oil (800 mg DHA a day) from 20 weeks of pregnancy to delivery did not change body fat of 252 children at 7 years (BOD POD difference -0.35 points, 95% CI -1.46 to 2.16). — 252 children at 7 y born to women in the DOMInO trial, Adelaide, tuna oil 800 mg/day DHA vs placebo from 20 weeks gestation (n = 252) Evidence B source
  Percentage body fat adjusted mean difference -0.35 (95% CI -1.46, 2.16) by BOD POD, 0.64 (95% CI -0.99, 2.27) by BIS

Safety, limits and interactions

• The same 16-week herring and mackerel lunches raised hair mercury in 4 to 6 year olds by 0.83 standard deviations versus meat, one of the four strongest effects among 86 biomarkers. — 232 randomized children aged 4-6 y, Norway, hair samples n = 210 (n = 232) Evidence B source
  Hair mercury SMD 0.83 (95% CI 0.05, 1.05)
• Across 103 histamine poisoning incidents in 55 reports the fish involved was mainly tuna or marlin-type species, with a pooled mean of 1107 mg/kg histamine in the implicated food. — 55 outbreak reports, 103 incidents, 1959-2013 (n = 103 incidents) Evidence C source
  Mean histamine 1107.21 mg/kg (CI 422.62-2900.78), I2 100%
• A systematic review of canned tuna contaminants found the methylmercury hazard quotient above 1 for children in 12 countries, while cadmium, lead and nickel posed no non-cancer risk. — published surveys of canned tuna, adults and children, many countries Evidence C source
  THQ for methylmercury above 1 for children in 12 countries and adults in Tunisia
• Among 108 Singaporean children with IgE-mediated fish allergy, 75.9% could tolerate another fish species, tuna in 24.1% of cases. — 108 children with IgE-mediated fish allergy, tertiary hospital, Singapore, 2015-2020 (n = 108) Evidence C source
  75.9% tolerated another species, tuna 24.1%, anaphylaxis 6.5%
• FDA/EPA list Atlantic and Pacific chub mackerel and canned light tuna as Best Choices, albacore tuna as a Good Choice, and king mackerel and bigeye tuna as Choices to Avoid. — US consumers, especially pregnant or breastfeeding people and children Evidence E source
  Category by species

What people believe that the data does not support

• Neither fish has an EU health claim of its own, but the EU register authorizes the claim that EPA and DHA contribute to normal heart function. — EU labeling Evidence E source
  Authorized claim; the register row gives no condition of use
• The EU refused the claim that DHA helps control body weight or reduces body fat. — EU labeling Evidence E source
  Non-authorized claim

Who this works differently for

• FDA/EPA advise pregnant or breastfeeding people to eat 8 to 12 ounces of lower-mercury seafood a week and name Atlantic mackerel among the lowest-mercury fish for children eating higher amounts. — pregnant or breastfeeding people, children Evidence E source
  8-12 oz per week

What is still unknown

• USDA Foundation Foods measured selenium from 68.7 to 85.0 ug and sodium from 26.5 to 243 mg per 3.5 oz (100 g) across 6 yellowfin tuna samples, and has no sampled spread for mackerel at all. — 6 samples of frozen wild-caught yellowfin tuna (n = 6) Evidence E source
  Selenium 68.7-85.0 ug, sodium 26.5-243 mg per 3.5 oz (100 g)
• USDA retention factors for baked finfish predict 15% loss of vitamin B12 in fatty fish such as mackerel and 10% in lean fish such as tuna, with no mineral loss, and give nothing for EPA or DHA. — USDA group factors, finfish over and under 5% fat, baked without drippings Evidence E source
  B12 retained 85% (fat over 5%) vs 90% (under 5%), thiamin 95% vs 90%, minerals 100%

The bottom line

UK women aged 20 to 39 ate 1.2 oz (33 g) of oily fish a week on average in 2008 to 2021, a quarter of the 140 g the NHS recommends, by four-day food diaries that may under-report. The authors name mackerel as a fish to push. In the US survey database a standard can of mackerel weighs 2.6 oz (75 g) and a standard can of tuna 115 g. Most tuna studies here used tuna oil, which is a different product from the fish. In 60 healthy Malaysian toddlers, tuna oil in microencapsulated formula powder gave higher blood DHA after one month than the same oil added plain, and the abstract gives no size. In the DOMInO trial, tuna oil capsules with 800 mg DHA a day from 20 weeks of pregnancy left body fat unchanged in 252 children at age 7 (difference -0.35 points, 95% CI -1.46 to 2.16). That was a trial dose given under study conditions, not a recommendation, and we have no card on taking fish oil alongside any medicine. The EU refused the claim that DHA helps control body weight. It authorizes the claim that EPA and DHA contribute to normal heart function, the register row we hold gives no condition of use, and neither fish carries a claim of its own. USDA group factors from 1975 predict that baking keeps 85% of vitamin B12 in fatty fish and 90% in lean fish, and they give no figure for EPA or DHA. Who should be careful. Pregnant and breastfeeding people and young children should choose by species. FDA and EPA list Atlantic mackerel, Pacific chub mackerel and canned light tuna as Best Choices, albacore as a Good Choice, and king mackerel and bigeye tuna as Choices to Avoid, a ranking built on mercury with omega-3 left out. They advise 8 to 12 ounces a week of lower-mercury seafood in pregnancy and breastfeeding, and name Atlantic mackerel among the lowest-mercury fish for children. A review of canned tuna surveys put the methylmercury hazard quotient above 1 for children in 12 countries. That quotient is modeled from concentrations and does not measure harm in any child. In 103 histamine poisoning incidents from 55 reports, the fish was mainly tuna or marlin-type species, with a pooled 1107 mg/kg histamine in the implicated food and extreme heterogeneity between reports. Iranian canned tuna averaged 77.86 mg/kg across 693 samples, under the 200 mg/kg FDA limit, which says nothing about fresh tuna, and we have no card on how fresh tuna should be kept cold to prevent histamine poisoning. Anisakid larvae turned up in 0.64% of muscle samples of Mediterranean anchovy, pilchard and Atlantic mackerel pooled together, which matters for fish eaten raw or lightly preserved. We have no card on how freezing or cooking makes such fish safe, so this page is not a guide to eating mackerel raw or lightly marinated. Among 108 children with fish allergy at one Singapore hospital, 75.9% tolerated some other fish, tuna in 24.1% of cases, and that tolerance was not tested blind. We have no card on drug interactions for either fish. Mackerel brings far more omega-3 and vitamin D per 3.5 oz (100 g). Canned light tuna and Atlantic mackerel both sit on the lowest mercury list. Six USDA samples of yellowfin tuna ranged from 26.5 to 243 mg sodium per 3.5 oz (100 g), and USDA has no sampled spread for mackerel at all.

Sources

1. mvt-r3-06 · meta-analysis of surveys
   resulted in 11 articles and a total of 693 samples for inclusion in this review...The mean concentration was calculated as 77.86 mg kg−1 (95% confidence interval [CI], 47.51 to 108.21 mg kg−1), which was lower than the 200 mg kg−1 recommended limit by the U.S. Food and Drug Administration (FDA).
   J Food Prot, 2018 · checked 2026-09-28
2. mvt-r3-11 · agency data table
   MACKEREL ATLANTIC (N.Atlantic) | 0.05 | N/A | N/A | 0.02 | 0.16 | 80 | NMFS REPORT 1978...TUNA (CANNED, LIGHT) | 0.126 | 0.077 | 0.134 | ND | 0.889 | 545 | FDA 1991-2010...TUNA (FRESH/FROZEN, BIGEYE) | 0.689 | 0.56 | 0.341 | 0.128 | 1.816 | 21 | FDA 1993-2005...MACKEREL KING | 0.73 | N/A | N/A | 0.23 | 1.67 | 213 | GULF OF MEXICO REPORT 2000
   FDA, Mercury Levels in Commercial Fish and Shellfish (1990-2012), content current 2022-02-25 · checked 2026-09-28
3. mvt-r3-14 · composition dataset
   16-393 Mackerel, flesh only, raw | Fat 17.9 g | n-3 poly 4.05 g | Vitamin D 8.0 ug | Selenium 42 ug | Iodine 29 ug || 16-399 Tuna, flesh only, raw | Fat 0.7 g | n-3 poly 0.09 g | Vitamin D 3.2 ug | Selenium 93 ug | Iodine 18 ug
   CoFID 2021 (Public Health England), codes 16-393 and 16-399, OGL v3.0 · checked 2026-09-28
4. mvt-r3-10 · dietary survey
   Women aged 20-39 years consumed an average of 33 g of oily fish per week in the period 2008-2021. This is only 24% of the NHS recommended intake of 140 g...Efforts to increase consumption of oily fish species such as mackerel and sardines are likely to be viable and effective for improving women's public health.
   Int J Food Sci Nutr, 2026 · checked 2026-09-28
5. mvt-r3-16 · portion dataset
   Fish, mackerel, canned | 1 standard can 75 g | 1 large can 420 g | Quantity not specified 85 g || Fish, tuna, canned | 1 standard can 115 g | 1 small can 75 g | 1 pouch 75 g | 1 large can 255 g
   USDA FNDDS, fdc_id 2706268 and 2706311 · checked 2026-09-28
6. mvt-r3-01 · RCT
   We randomly allocated (1:1) 232 children, aged 4 to 6 y, from 13 kindergartens. The children received lunch meals of either fatty fish (herring/mackerel) or meat (chicken/lamb/beef) 3 times a week for 16 wk...We found significant effects of the intervention on the following biomarkers: RBC EPA (20:5n-3), 0.61 (95% CI: 0.36, 0.86); DHA (22:6n-3), 0.43 (95% CI: 0.21, 0.66)
   J Nutr, 2021 · checked 2026-09-28
7. mvt-r3-03 · RCT
   to investigate the bioavailability of microencapsulated omega-3 DHA formulations in healthy toddlers compared with high DHA fish oil for a one-month period...Sixty toddlers were randomly allocated to four groups...The results showed an enhanced bioavailability with significantly greater concentrations of blood DHA levels in formulas with microencapsulated powders.
   Nutrients, 2020 · checked 2026-09-28
8. mvt-r3-08 · meta-analysis of surveys
   anchovy, pilchard, and Atlantic mackerel...Anisakids prevalence in fish muscle was 0.64% (P < 0.0001), in viscera it was 1.34% (P < 0.0001), and overall prevalence was 0.95% (P < 0.0001).
   Crit Rev Food Sci Nutr, 2016 · checked 2026-09-28
9. sf-fpf-r1-5 · agency advice
   Freezing and storing at an ambient temperature of -4°F (-20°C) or below for 7 days (total time), or freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -31°F (-35°C) or below for 15 hours, or freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -4°F (-20°C) or below for 24 hours are sufficient to kill parasites. ... The process of heating raw fish sufficiently to kill bacterial pathogens is also sufficient to kill parasites.
   FDA, Fish and Fishery Products Hazards and Controls Guidance, Chapter 5: Parasites · checked 2026-10-08
10. mvt-r3-04 · RCT follow-up
    women took either high-DHA tuna oil (800mg/day DHA) or placebo capsules from 20 weeks' gestation to delivery...A total of 252 DOMInO children (n=135 males, n=117 females) completed the follow up study. There were no differences between the DHA and placebo groups in percentage body fat as assessed by either BOD POD [adjusted mean difference: -0.35, 95% CI: -1.46, 2.16; P=0.71] or BIS [adjusted mean difference: 0.64, 95% CI: -0.99, 2.27; P=0.44].
    Prostaglandins Leukot Essent Fatty Acids, 2018 · checked 2026-09-28
11. mvt-r3-02 · RCT
    hair mercury, 0.83 (95% CI: 0.05, 1.05)...Of the 86 biomarkers, the strongest effect of fatty fish intake was on n-3 PUFAs, UIC, hair mercury, and plasma 1-MH.
    J Nutr, 2021 · checked 2026-09-28
12. mvt-r3-05 · meta-analysis of outbreak reports
    Fifty-five (55) reports were included, these studies reported 103 incidents...histamine mean concentration in poisoning samples was 1107.21 mg/kg with confidence interval for the meta-mean of 422.62-2900.78 mg/kg...Fish involved in histamine poisoning was mainly tuna or Istiophoridae species.
    Crit Rev Food Sci Nutr, 2018 · checked 2026-09-28
13. mvt-r3-07 · systematic review of surveys
    The concentrations of Cd, Pb, and Ni were higher than the standard limits but they did not pose any non-carcinogenic health risks in adult and children's consumers (THQ <1)...Moreover, the THQ value due to Me Hg for adult in Tunisia and for children in Tunisia, Malta, Portugal, Latvia, Cambogia, Peru, South Korea, Romania, Hong Kong, United Arab Emirates, Morocco, and Egypt was higher than 1 value.
    Int J Environ Health Res, 2024 · checked 2026-09-28
14. mvt-r3-09 · retrospective cohort
    Anaphylaxis occurred in 6.5%...Most can tolerate another species of fish (75.9%), most commonly salmon (37.0%), tuna (24.1%) and cod (22.2%).
    Asian Pac J Allergy Immunol, 2025 · checked 2026-09-28
15. mvt-r3-12 · agency advice
    Atlantic mackerel | Best Choice...Pacific chub mackerel | Best Choice...Tuna, canned light (includes skipjack) | Best Choice...Tuna, albacore/white tuna, canned and fresh/frozen | Good Choice...King mackerel | Choice to Avoid: HIGHEST MERCURY LEVELS...Tuna, bigeye | Choice to Avoid: HIGHEST MERCURY LEVELS
    FDA/EPA, Advice about Eating Fish, page updated 2024-03-05 · checked 2026-09-28
16. mvt-r3-18 · regulatory decision
    POL-HC-6368 Eicosapentaenoic acid and docosahexaenoic acid (EPA/DHA) EPA and DHA contribute to the normal function of the heart Authorised
    EU Register on nutrition and health claims, claim POL-HC-6368, snapshot 2026-09-21 · checked 2026-09-28
17. mvt-r3-19 · regulatory decision
    POL-HC-7029 Docosahexaenoic acid (DHA) Helps to control body weight when combined with a healthy diet and exercise. Fits in a weight maintainance programme. Contributes to the reduction of body fat. Helps to control fat metabolism. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7029, snapshot 2026-09-21 · checked 2026-09-28
18. mvt-r3-13 · agency advice
    consume between 8 and 12 ounces per week of a variety of seafood from choices that are lower in mercury...children should only be fed fish from the “Best Choices” list that are even lower in mercury – these fish are anchovies, Atlantic mackerel
    FDA/EPA, Advice about Eating Fish, page updated 2024-03-05 · checked 2026-09-28
19. mvt-r3-15 · composition dataset
    Tuna, ahi or yellowfin, frozen, wild caught | Selenium, Se 76.52 UG range 68.7-85.0 n=6 | Sodium, Na 94.37 MG range 26.5-243.0 n=6 || mackerel: no Foundation Foods rows
    USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-28
20. mvt-r3-17 · retention dataset
    USDA-RETN-R6:2451 FINFISH,>5%FAT,BAKED,WO/DRIPPINGS | vitamin_b12_ug 85% | thiamin_mg 95% | iron_mg 100% || USDA-RETN-R6:2301 FINFISH,<5%FAT,BAKED,WO/DRIPPINGS | vitamin_b12_ug 90% | thiamin_mg 90% | iron_mg 100%
    USDA Table of Nutrient Retention Factors, Release 6 (2007) · checked 2026-09-28