Herring: a lean-meat swap that moved one number

The trial that carries this page swapped one dinner for another. Thirty-five overweight men ate 150 g of baked herring five days a week for six weeks, and their HDL came out at 1.04 mmol/l against 0.99 after the same weight of baked lean pork and chicken. Triacylglycerol fell on both diets with no difference between them. C-reactive protein, IL-6, IL-18, ICAM-1 and oxidised LDL did not move. The same research group in Gothenburg had run a four-week version in 15 obese adults aged 24 to 70, of whom 13 finished, and HDL there came out at 1.22 mmol/l against 1.13 on the reference diet (P = 0.036). Neither trial measured a rise from where these people started. Both compared one diet period against the other. Two trials from one team is the same finding twice and not an independent replication. HDL is what shifted in both, and nothing else did. Herring roe oil is a different product from the fish. In 32 adults with fasting triacylglycerol between 100 and 399 mg/dL, omega-3 from phospholipid-rich herring roe oil reached plasma phosphatidylcholine faster over the first 12 hours than the same dose of triglyceride fish oil. After two weeks on either one, fasting levels had risen about threefold from baseline, with no difference between the two capsules (p = 0.422). The head start lasts a day and not a fortnight.

The numbers, per 100 g

What a real portion looks like

• In a model of 3016 Danish adults held to EPA, DHA and vitamin D targets and to ceilings for methylmercury and dioxins, herring was the fish that met the constraints at the lowest cost. — 3016 Danish adults whose intake and body weight were recorded in a national dietary survey, modelled by quadratic programming against intake recommendations and tolerable contaminant levels (n = 3016) Evidence C source
  Minimising cost alone pointed 99% of the population to herring as the least-expensive species that still fits the constraints; 22 individuals (0.7%) could not be given any solution because their background contaminant exposure was already too high

What your body absorbs

• Omega-3 from phospholipid-rich herring roe oil reached plasma phosphatidylcholine faster over 12 hours than the same dose from triglyceride fish oil in 32 adults, and after two weeks the two were level. — 32 adults with fasting triacylglycerol between 100 and 399 mg/dL, randomised single-blind crossover, 12 capsules a day of phospholipid-rich herring roe oil or triglyceride-rich fish oil for two weeks each with a four-week washout (n = 32) Evidence B source
  Net incremental area under the curve from 0 to 12 h for EPA, DHA and EPA+DHA in plasma phosphatidylcholine higher after herring roe oil (p<0.01 for all); after two weeks fasting plasma PC EPA+DHA rose about 2.8 to 3.0-fold from baseline in both, with no difference in the change between them (p=0.422)
• Fourteen days of capsules made from herring roe phospholipids lowered fasting triacylglycerol and raised HDL in 21 healthy young adults, with no control group. — 21 healthy adults aged 21 to 26, 20 women and one man, taking 11 capsules a day of a herring roe phospholipid supplement for 14 days, giving 1738 mg DHA and 616 mg EPA daily (n = 21) Evidence C source
  Fasting triacylglycerol and non-esterified fatty acids fell and HDL-cholesterol rose (p < 0.05); blood glucose at 10 and 120 minutes of an oral glucose tolerance test lower after supplementation; most measures back to baseline four weeks after stopping

What cooking and storage change

• Anisakis larvae were in 15% to 60% of Norwegian spring spawning herring fillets depending on fish size, and the visual candling used by industry found only 7% to 10% of the larvae actually present. — Norwegian spring spawning herring (Clupea harengus), blue whiting and mackerel from the Northeast Atlantic, examined in size groups by candling, enzymatic degradation and UV illumination Evidence C source
  Larvae in fillets 15 to 60% in herring, 32 to 77% in mackerel, 89 to 100% in blue whiting; candling detected 7 to 10% of the larvae present, and its efficiency did not depend on fillet thickness

What it does to your health

• Six weeks of 150 g baked herring five days a week left HDL higher than the same amount of lean pork and chicken, 1.04 against 0.99 mmol/l, in 35 overweight men. — 35 healthy but overweight men, mean BMI 28.3, crossover with a 12-week washout, 150 g baked herring fillets a day 5 days a week against 150 g baked lean pork and chicken fillets (n = 35) Evidence B source
  HDL 1.04 vs 0.99 mmol/l after herring; triacylglycerol fell on both diets with no difference between them; no change in C-reactive protein, IL-6, IL-18, ICAM-1 or oxidised LDL

Safety, limits and interactions

• Allergic anisakiasis clusters where the infected fish are, and Portugal and Norway carry the highest reported rates at 18.45% to 22.50%. — systematic review of 264 articles on anisakid infection in fish and 37 on allergic anisakiasis in humans, January 2000 to August 2020, 152 fish host species (n = 301 articles) Evidence C source
  Highest reported allergic anisakiasis rates 18.45 to 22.50% in Portugal and Norway; hot spots across the North and northeast Atlantic, Norway, the UK and west of Iceland at 99% confidence; the five most infected fish families were Lophiidae 86.9%, Trichiuridae 77.05%, Zeidae 70.9%, Merlucciidae 67.8% and Gadidae 56.8%
• Eating about 630 g of fatty fish a week for six months did not raise serum levels of any of 15 persistent organic pollutants in 131 overweight adults. — 131 men and women aged 35 to 70 with BMI between 25 and 38 and at least one cardiometabolic component, randomised to fatty fish about 630 g/week (45), nuts about 200 g/week (42) or usual diet avoiding both (44) for 6 months (n = 131) Evidence B source
  No difference from controls in any of 5 organochlorines, 2 dioxin-like PCBs or 8 non-dioxin-like PCBs (p > 0.05); HDL-cholesterol rose in the fish group by 0.10 mmol/L (95% CI 0.05 to 0.20, p = 0.005)

What people believe that the data does not support

• Twelve people sensitised to the herring worm swallowed up to 100 freeze-dried larvae under double-blind conditions and none of them reacted. — 12 patients with positive skin tests and specific IgE to Anisakis simplex and negative skin tests to fish, given capsules of lactose or 1, 5 or 25 lyophilised larvae at 2-hour intervals, highest single dose 100 larvae (n = 12) Evidence B source
  No positive reaction to placebo, lyophilised larvae or antigen; serum tryptase and eosinophil cationic protein unchanged; conjunctival provocation positive in 11 of the 12 and in none of 5 controls

Who this works differently for

• An earlier four-week version of the same swap left HDL higher than the reference diet, 1.22 against 1.13 mmol/l, in 15 obese men and women, 13 of whom finished. — 15 healthy obese men and women aged 24 to 70, 13 completed, randomised crossover with a 2-week washout, 150 g baked herring fillets a day 5 days a week against pork and chicken fillets (n = 15 enrolled, 13 completed) Evidence B source
  Plasma HDL 1.22 vs 1.13 mmol/l (P=0.036); small non-significant fall in triacylglycerol; C-reactive protein tended lower; no effect on apolipoprotein A or B, lipoprotein (a) or fibrinogen
• FDA and EPA put herring in the Best Choices group of their fish advice, the group they tell pregnant and breastfeeding people to eat 2 to 3 servings of each week. — people who might become pregnant, are pregnant or are breastfeeding, and children aged 1 to 11, in the United States Evidence E source
  2 to 3 servings a week of Best Choices fish for adults in this group and 2 servings a week for children; herring appears as a row in the Best Choices table, which is sorted by measured mercury content

What is still unknown

• Four weeks of herring instead of chicken and lean pork shifted plasma citrate, fumarate, oxalate and several amino acid metabolites in 15 overweight adults, by a route the authors say is not the omega-3. — 15 healthy obese men and women aged 24 to 70, randomised crossover, four weeks of herring or a reference diet of chicken and lean pork, five meals a week, fasting serum metabolome by GC-MS in the 11 subjects with samples (n = 15 randomised, 11 analysed) Evidence B source
  Herring lowered plasma citrate, fumarate, isocitrate, glycolate, oxalate, agmatine and methylhistidine and raised asparagine, ornithine, glutamine and glucosamine; blood nitric oxide rose in the men

The bottom line

The caution with the most measurement behind it is a worm. Anisakis larvae were present in 15 to 60 percent of Norwegian spring spawning herring fillets depending on the size of the fish, and most larvae sat in the abdominal cavity rather than the flesh. The candling lamp the industry inspects with found only 7 to 10 percent of the larvae that were there, and the thickness of the fillet made no difference to that. This is why raw and lightly cured herring goes through a freezer, because looking at it does not work. Dead larvae appear to be another matter. Twelve people with positive skin tests and IgE to Anisakis simplex swallowed capsules of freeze-dried larvae under double-blind conditions, up to 100 at the top dose. None of them reacted, while the same larvae given to the eye gave a positive response in 11 of the 12. Twelve people cannot rule out a rare reaction. Where the infected fish are, more allergy is reported, and a systematic review puts the highest rates in Portugal and Norway at 18.45 to 22.50 percent, among people investigated for allergy rather than in the population at large. Contaminants are the other thing people ask about oily fish. Over six months, adults eating about 630 g of fatty fish a week showed no rise against controls in any of 15 persistent organic pollutants, and their HDL rose by 0.10 mmol/L (95 percent CI 0.05 to 0.20). The fish in that trial was mostly farmed salmon, and Baltic herring, the stock that carries a dioxin derogation, was not tested. FDA and EPA place herring in their Best Choices group, and they advise 2 to 3 servings a week from that group for people who are pregnant or breastfeeding, and 2 servings for children aged 1 to 11. That advice ranks fish by measured mercury, so dioxins are not what it sorts on. Price points the same way. A Danish model held 3016 adults to omega-3 and vitamin D targets and to ceilings for methylmercury and dioxins. Herring came out as the cheapest species that fits for 99 percent of them, at Danish prices and against a Danish contaminant background. For 22 of those people, 0.7 percent, no solution existed at all, because their background exposure was already too high. Two gaps are worth naming. Four weeks of herring shifted plasma citrate, fumarate, oxalate and several amino acid metabolites in the 11 participants whose samples were analysed, by a route the authors say is not the omega-3, and that is mechanism rather than health. We found no measurement of tyramine in herring, so this page cannot say what pickled herring means for anyone taking a monoamine oxidase inhibitor, and a gap in what we could find is not evidence that there is nothing to find. Capsules of herring roe phospholipids lowered fasting triacylglycerol and raised HDL over 14 days in 21 healthy adults aged 21 to 26, in a study with no control group, and most measures were back to baseline four weeks after they stopped.

Sources

1. herr-r4-10 · cross-sectional survey modelling
   When only minimising cost, the vast majority (99 %) should be recommended to only consume herring, which is the least-expensive fish species.
   Br J Nutr, 2019 · checked 2026-09-24
2. herr-r4-04 · randomised controlled trial
   The net incremental area under the curve from 0 to 12h for EPA, DHA, and EPA+DHA in plasma phosphatidylcholine (PC) were significantly higher (p<0.01 for all) after Romega 30 supplementation compared to fish oil.
   Prostaglandins Leukot Essent Fatty Acids, 2016 · checked 2026-09-24
3. herr-r4-05 · single-arm clinical trial
   Fasting plasma triacylglycerol and non-esterified fatty acids decreased and HDL-cholesterol increased after 14 days of MOPL30 intake (p < 0.05).
   Lipids Health Dis, 2014 · checked 2026-09-24
4. herr-r4-06 · prevalence and method comparison study
   However, the prevalence of Anisakis larvae in fish fillets varied considerably among the size groups of each species: 15 to 60% in herring, 32 to 77% in mackerel, and 89 to 100% in blue whiting.
   J Food Prot, 2005 · checked 2026-09-24
5. herr-r4-01 · randomised controlled trial
   HDL was significantly higher after the herring diet period compared with after the reference diet period: 1.04 v. 0.99 mmol/l.
   Br J Nutr, 2009 · checked 2026-09-24
6. herr-r4-07 · systematic review
   The highest rate of allergic anisakiasis was in Portugal and Norway with the prevalence rate of 18.45-22.50%.
   Parasitol Res, 2020 · checked 2026-09-24
7. herr-r4-09 · randomised controlled trial
   Results showed that changes in concentrations of individual and classes of POPs did not differ between the dietary groups and controls (p > 0.05).
   Nutr Metab Cardiovasc Dis, 2020 · checked 2026-09-24
8. herr-r4-08 · randomised double-blind placebo-controlled trial
   The ingestion of 100 lyophilized A. simplex larvae, or its equivalent in antigen, does not induce clinical symptoms in individuals with a clinical history and laboratory findings of hypersensitivity to A. simplex.
   Allergy, 2000 · checked 2026-09-24
9. herr-r4-02 · randomised controlled trial
   P-HDL was significantly higher after the herring diet period compared to after the reference diet period; 1.22 vs 1.13 mmol/l (P=0.036).
   Eur J Clin Nutr, 2007 · checked 2026-09-24
10. herr-r4-11 · agency advisory
    Eat 2 to 3 servings a week from the "Best Choices" list
    FDA and EPA, Advice about Eating Fish · checked 2026-09-24
11. herr-r4-03 · randomised controlled trial
    The herring diet decreased plasma citrate, fumarate, isocitrate, glycolate, oxalate, agmatine and methyhistidine and increased asparagine, ornithine, glutamine and the hexosamine glucosamine.
    Mol Nutr Food Res, 2017 · checked 2026-09-24