Herring Omega-3 Density — Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) per Serving

Table of Contents

1. Nutrient Density: Herring vs Other Fish and Supplements
2. Eicosapentaenoic Acid vs Docosahexaenoic Acid: Distinct Molecules, Distinct Roles
3. Bypassing the Alpha-Linolenic Acid-to-EPA Bottleneck
4. Cardiovascular Evidence: GISSI, REDUCE-IT, VITAL
5. Inflammation Resolution and Specialized Pro-Resolving Mediators
6. Neurocognitive Effects of Docosahexaenoic Acid
7. Dose Translation: Servings per Week
8. Whole-Food Fish vs Fish Oil Supplements
9. Oxidation, Storage, and Lipid Quality
10. Key Research Papers
11. Connections
12. Featured Videos

Nutrient Density: Herring vs Other Fish and Supplements

Marine omega-3 density per 100 g cooked serving, drawn from U.S. Department of Agriculture (USDA) FoodData Central and matched literature:

1. Atlantic mackerel — ~504 mg eicosapentaenoic acid and ~699 mg docosahexaenoic acid per 100 g
2. Atlantic herring — ~909 mg eicosapentaenoic acid and ~1,100 mg docosahexaenoic acid per 100 g (Pacific: ~1,810 mg)
3. Sardines (Atlantic, canned in oil, drained, with bone) — ~473 mg eicosapentaenoic acid and ~509 mg docosahexaenoic acid per 100 g
4. Wild Atlantic salmon — ~1,840 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g; farmed Atlantic: ~690 mg eicosapentaenoic acid and ~1,460 mg docosahexaenoic acid
5. Anchovies (canned in oil) — ~2,055 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g
6. Rainbow trout — ~840 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g
7. Albacore tuna (canned) — ~860 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g
8. Cod (Atlantic) — ~158 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g
9. Tilapia — ~115 mg eicosapentaenoic acid + docosahexaenoic acid per 100 g

For comparison, a typical 1,000 mg fish oil capsule contains 180 mg eicosapentaenoic acid + 120 mg docosahexaenoic acid = 300 mg combined omega-3. USDA's 3 oz (85 g) portion of cooked Atlantic herring holds about 773 mg eicosapentaenoic acid and 935 mg docosahexaenoic acid — several capsules' worth, without the rancidity, encapsulation cost, or pill burden — and together more than the American Heart Association recommendation of 1,000 mg/day for patients with established coronary heart disease in a single serving.

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Eicosapentaenoic Acid vs Docosahexaenoic Acid: Distinct Molecules, Distinct Roles

Eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) are often referenced jointly as "marine omega-3," but they are structurally and functionally distinct:

1. Eicosapentaenoic acid — 20-carbon backbone, 5 double bonds. Serves as substrate for the 3-series prostaglandins and 5-series leukotrienes, which are markedly less inflammatory than the AA-derived 2-series prostaglandins and 4-series leukotrienes. Eicosapentaenoic acid is also the precursor to the E-series resolvins. Eicosapentaenoic acid appears to drive most of the cardiovascular and triglyceride-lowering effects of marine omega-3.
2. Docosahexaenoic acid — 22-carbon backbone, 6 double bonds. Selectively incorporated into neural and retinal phospholipids; docosahexaenoic acid accounts for ~30–40% of the fatty acid composition of brain gray matter phospholipids and ~60% of photoreceptor outer-segment phospholipids. Substrate for D-series resolvins and protectins. Docosahexaenoic acid drives most of the neurocognitive and visual development effects.

Herring delivers eicosapentaenoic acid and docosahexaenoic acid in roughly equal proportion (typically 700–900 mg each per 100 g), making it a balanced source for both effect categories. By contrast, krill oil is eicosapentaenoic acid-heavy with much less docosahexaenoic acid, and algae-derived supplements are typically docosahexaenoic acid-dominant with minimal eicosapentaenoic acid.

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Bypassing the Alpha-Linolenic Acid-to-EPA Bottleneck

The plant-source omega-3 alpha-linolenic acid (ALA, 18:3n-3, found in flaxseed, walnuts, and chia) must be elongated and desaturated in vivo to produce eicosapentaenoic acid and docosahexaenoic acid. The pathway requires the delta-6 desaturase enzyme (FADS2), elongase enzymes, and the delta-5 desaturase — with the same enzymatic machinery shared by the competing n-6 pathway converting linoleic acid to arachidonic acid.

Conversion efficiency in adults is poor:

• Alpha-linolenic acid → eicosapentaenoic acid conversion: approximately 5% in adult men, 21% in women of reproductive age (estrogen upregulates the pathway)
• Alpha-linolenic acid → docosahexaenoic acid conversion: approximately 0–9% in adult men, 9% in women
• The pathway is further suppressed by high dietary linoleic acid (the typical Western 10:1 to 20:1 n-6:n-3 ratio drives the desaturase enzymes toward arachidonic acid synthesis)

The practical implication is that consuming 10 g of alpha-linolenic acid from flaxseed delivers an expected 0.5 g of eicosapentaenoic acid and 0–1 g of docosahexaenoic acid, with high inter-individual variation driven by FADS gene polymorphisms. The same gram of eicosapentaenoic acid + docosahexaenoic acid from herring requires no conversion and is incorporated into cell membranes within hours of consumption. For individuals with the FADS1 rs174537 minor allele (common in populations of European ancestry), conversion efficiency is further reduced, making direct dietary eicosapentaenoic acid + docosahexaenoic acid from fish particularly important.

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Cardiovascular Evidence: GISSI, REDUCE-IT, VITAL

The cardiovascular omega-3 trial landscape includes both landmark positive studies and recent null trials that have refined the indication:

1. GISSI-Prevenzione (1999) — 11,324 Italian post-MI patients randomized to 1 g/day eicosapentaenoic acid + docosahexaenoic acid, Vitamin E, both, or neither for 3.5 years. The omega-3 arm showed a 20% reduction in all-cause mortality, 30% reduction in cardiovascular death, and 45% reduction in sudden cardiac death. The study established secondary-prevention omega-3 as a class IIa American Heart Association (AHA) recommendation.
2. JELIS (2007) — 18,645 Japanese hypercholesterolemic patients randomized to statin + 1.8 g/day eicosapentaenoic acid vs statin alone. The eicosapentaenoic acid arm showed a 19% reduction in major coronary events.
3. REDUCE-IT (2019) — 8,179 patients with established cardiovascular disease (CVD) or diabetes + elevated triglycerides randomized to icosapent ethyl (4 g/day purified eicosapentaenoic acid) vs mineral oil placebo. The eicosapentaenoic acid arm showed a 25% reduction in major adverse cardiovascular events at 4.9 years — the largest cardiovascular benefit of any omega-3 trial to date, driven by purified eicosapentaenoic acid at a pharmacological dose.
4. VITAL (2019) — 25,871 US adults randomized to 1 g/day eicosapentaenoic acid + docosahexaenoic acid for primary prevention. The trial was null for the composite cardiovascular endpoint but showed a 28% reduction in myocardial infarction (MI) as a secondary endpoint, and a 17% reduction in CV events in participants consuming <1.5 servings of fish per week at baseline.
5. STRENGTH (2020) — 13,078 patients randomized to a mixed eicosapentaenoic acid + docosahexaenoic acid carboxylic acid formulation vs corn oil placebo. The trial was null, raising questions about whether the REDUCE-IT effect was driven by pure eicosapentaenoic acid specifically (vs mixed eicosapentaenoic acid + docosahexaenoic acid) or by an unfavorable mineral oil placebo effect.

The 2018 American Heart Association Science Advisory on seafood omega-3 fatty acids (Rimm et al., Circulation) concluded that 1 to 2 seafood meals per week be included to reduce the risk of congestive heart failure, coronary heart disease, ischemic stroke, and sudden cardiac death, especially when seafood replaces the intake of less healthy foods.

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Inflammation Resolution and Specialized Pro-Resolving Mediators

The traditional model of omega-3 anti-inflammatory action emphasized competitive substrate displacement at the cyclooxygenase and lipoxygenase enzymes — eicosapentaenoic acid-derived 3-series prostaglandins are less inflammatory than AA-derived 2-series prostaglandins. Charles Serhan's laboratory at Harvard reframed the mechanism beginning in the early 2000s with the discovery of specialized pro-resolving mediators (SPMs), a family of lipid signaling molecules synthesized from eicosapentaenoic acid and docosahexaenoic acid that actively terminate inflammation rather than passively reducing it.

SPM families include:

• E-series resolvins (RvE1, RvE2, RvE3) — synthesized from eicosapentaenoic acid via 5-lipoxygenase, drive macrophage clearance of apoptotic cells
• D-series resolvins (RvD1 through RvD6) — synthesized from docosahexaenoic acid, inhibit neutrophil infiltration and promote tissue repair
• Protectins (PD1/NPD1) — synthesized from docosahexaenoic acid, neuroprotective in models of ischemic and inflammatory central nervous system (CNS) injury
• Maresins — synthesized from docosahexaenoic acid by macrophages, drive tissue regeneration and pain resolution

The clinical implication is that adequate dietary eicosapentaenoic acid + docosahexaenoic acid is not just an "anti-inflammatory" intervention — it is a substrate requirement for the active resolution phase that follows acute inflammation. Inadequate SPM synthesis is implicated in the chronic, non-resolving inflammation that characterizes atherosclerosis, periodontal disease, and rheumatoid arthritis.

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Neurocognitive Effects of Docosahexaenoic Acid

Docosahexaenoic acid accounts for 30–40% of phospholipid fatty acids in the gray matter of the cerebral cortex and 60% of phospholipid fatty acids in retinal photoreceptor outer segments. Dietary docosahexaenoic acid crosses the blood-brain barrier via the MFSD2A transporter as lysophosphatidylcholine-DHA and is incorporated into neural membrane phospholipids over a timescale of weeks to months.

Functional implications:

• Fetal and infant neurodevelopment — docosahexaenoic acid accumulates rapidly in the developing brain during the third trimester and first two years of life. The ALSPAC cohort (Hibbeln 2007 Lancet) found that maternal fish consumption <340 g/week in pregnancy was associated with reduced verbal IQ in offspring at age 8.
• Cognitive aging — the MIDAS trial (Yurko-Mauro 2010) randomized 485 healthy adults aged 55+ with age-associated memory complaints to 900 mg/day docosahexaenoic acid vs placebo for 24 weeks, showing improved episodic memory scores in the docosahexaenoic acid arm.
• Alzheimer's disease — observational cohort data consistently show reduced AD incidence in individuals with higher omega-3 intake and higher plasma docosahexaenoic acid. Interventional trials in established AD have been null, suggesting the benefit may be limited to prevention rather than treatment.
• Mood and depression — meta-analyses suggest a modest antidepressant effect of eicosapentaenoic acid-predominant formulations at doses of 1–2 g/day, with weaker evidence for docosahexaenoic acid-predominant or low-dose preparations.

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Dose Translation: Servings per Week

The 2020–2025 US Dietary Guidelines recommend 8 oz (227 g) of seafood per week for the general adult, with at least one of the servings being a low-mercury oily fish. The American Heart Association recommends two 3.5-oz (100 g) servings per week of oily fish for cardiovascular health. Translating those targets to herring:

1. For general health — one 100 g serving of cooked herring per week supplies about 909 mg eicosapentaenoic acid and 1,100 mg docosahexaenoic acid (USDA), which averaged over the week is above the 250 mg/day European Food Safety Authority (EFSA) adequate intake for adults.
2. For cardiovascular secondary prevention — two 100 g servings of herring per week average out to less than the 1 g/day of n-3 fatty acids given as capsules in GISSI-Prevenzione.
3. For triglyceride lowering (3–4 g/day target) — dietary herring alone cannot reach the pharmacological dose, which in trials such as REDUCE-IT came from prescription icosapent ethyl or omega-3 ethyl esters.
4. For pregnancy and lactation — the U.S. Food and Drug Administration (FDA) "best choices" list recommends 8–12 oz/week of low-mercury fish; herring is explicitly listed as a safe choice.

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Whole-Food Fish vs Fish Oil Supplements

Whole-food fish has several advantages over fish oil supplements that are not captured in the eicosapentaenoic acid + docosahexaenoic acid gram-equivalent comparison:

• Protein — 100 g of herring delivers ~18 g of complete protein with a high biological value (PDCAAS ~1.0) and the full essential amino acid profile.
• Vitamin D3, B12, selenium, iodine — co-delivered in the food matrix at meaningful doses (see Vitamin D and B12 deep-dive).
• Phospholipid-bound omega-3 — a meaningful fraction of herring omega-3 is in phospholipid form (phosphatidylcholine-EPA, phosphatidylcholine-DHA), which has higher bioavailability than the triglyceride or ethyl ester forms typical of fish oil capsules.
• Satiety and meal substitution — a serving of herring replaces a meal of lower-quality protein or refined carbohydrate, an effect a capsule cannot produce.
• Lower rancidity risk — whole fish, properly stored, has freshness signals (smell, color, texture) that consumers can evaluate. Fish oil capsules can be oxidized and rancid without detection until consumption.

The 2018 Cochrane systematic review (Abdelhamid et al., 79 randomized trials, 112,059 participants) concluded that increasing eicosapentaenoic acid and docosahexaenoic acid has little or no effect on mortality or cardiovascular health, with the evidence coming mainly from supplement trials.

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Oxidation, Storage, and Lipid Quality

The 5 and 6 double bonds in eicosapentaenoic acid and docosahexaenoic acid make them highly susceptible to peroxidation. Handling affects how much of herring's omega-3 survives:

• Fresh herring keeps best at 0–2°C, eaten within 1–2 days of purchase — lipid oxidation accelerates above 4°C.
• Freezing at −30°C for storage beyond 1 month — standard freezer temperatures (−18°C) preserve omega-3 for 2–3 months; lower temperatures extend usable life to 6–12 months.
• Brief cooking at moderate heat — baking, grilling, or pan-searing at <200°C preserves >90% of eicosapentaenoic acid + docosahexaenoic acid. Deep-frying at >180°C in seed oil causes both oxidation and dilution with n-6 frying oil.
• Vacuum-packed and canned herring — well-preserved omega-3 due to oxygen exclusion. Canned products typically retain 85–95% of the omega-3 of fresh.
• The visible fat holds much of the omega-3 — the eicosapentaenoic acid and docosahexaenoic acid are concentrated in the dark muscle and subcutaneous fat layer. Trimming visible fat removes a meaningful fraction of the omega-3 yield.

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Key Research Papers

1. GISSI-Prevenzione Investigators, dietary supplementation with omega-3 polyunsaturated fatty acids and vitamin E after myocardial infarction (Lancet 1999) — PubMed PMID: 10465168
2. Bhatt DL et al., REDUCE-IT cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia (NEJM 2019) — PubMed PMID: 30415628
3. Manson JE et al., VITAL marine n-3 fatty acids and prevention of cardiovascular disease and cancer (NEJM 2019) — PubMed PMID: 30415637
4. Yokoyama M et al., JELIS effects of EPA on major coronary events in hypercholesterolaemic patients (Lancet 2007) — PubMed PMID: 17398308
5. Nicholls SJ et al., STRENGTH effect of high-dose omega-3 fatty acids vs corn oil on major adverse cardiovascular events (JAMA 2020) — PubMed PMID: 33190147
6. Serhan CN, pro-resolving lipid mediators are leads for resolution physiology (Nature 2014) — PubMed PMID: 24899309
7. Burdge GC and Calder PC, conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults (Reprod Nutr Dev 2005) — Search PubMed
8. Yurko-Mauro K et al., MIDAS beneficial effects of docosahexaenoic acid on cognition in age-related cognitive decline (Alzheimers Dement 2010) — PubMed PMID: 20434961
9. Hibbeln JR et al., ALSPAC maternal seafood consumption in pregnancy and neurodevelopmental outcomes (Lancet 2007) — PubMed PMID: 17307104
10. Hu FB et al., fish and omega-3 fatty acid intake and risk of coronary heart disease in women (JAMA 2002) — Search PubMed
11. Mozaffarian D and Rimm EB, fish intake, contaminants, and human health (JAMA 2006) — PubMed PMID: 17047219
12. Calder PC, omega-3 polyunsaturated fatty acids and inflammatory processes (Biochim Biophys Acta 2015) — PubMed PMID: 25149823

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Connections

• All Food
• Omega-3 and Fish Oil for Rheumatoid Arthritis
• Benefits Hub
• Herring (Main Page)
• Vitamin D and B12
• Pickled vs Fresh
• Sustainability and Lower Mercury
• Omega-3 Fatty Acids
• Sardines
• Salmon
• Cardiology
• Neurology
• Anti-Inflammatory
• Omega-3 Index Test
• History
• Nutrients

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