--- topic: "Mackerel" title: "Omega-3s, Vitamin D, and Heart Health" order: 1 description: "A fatty fish delivering more omega-3s than most supplements alongside vitamin B12, vitamin D, and selenium — clinically proven to lower triglycerides and blood pressure." question: "Does eating mackerel lower triglycerides and blood pressure?" answer: "Mackerel likely lowers triglycerides and blood pressure, mainly because of its omega-3s, but the mackerel-specific trials are small and old." actions: - "Eat oily fish like mackerel 2–3 times a week (150–200 g servings); canned mackerel in water or olive oil is an affordable option." - "Choose Atlantic, chub or Spanish mackerel for regular eating; they are lower in mercury than king mackerel." - "Cook or eat fresh mackerel within a day or two of buying, as it spoils quickly; smoked mackerel is higher in sodium." cautions: - "Avoid king mackerel, which accumulates significantly more mercury." - "Pregnant women should choose Atlantic mackerel and check current local advisory limits, which are stricter." confidence: 3 confidenceNote: "Two small mackerel studies (14 men; 58 elderly adults) plus a Cochrane review of 79 omega-3 trials (112,000+ people) on supplements, not whole fish." evidenceSummary: rctCount: 1 metaAnalysisCount: 1 totalParticipants: "112,000+" replicated: false newestStudyYear: 2023 references: - id: "1" pmid: "36358100" title: "Fatty acids, selenium, and vitamin B12 in chub mackerel (Scomber colias) as nourishment considering seasonality and bioaccessibility as factors" authors: "Afonso C, Cardoso C, Gomes-Bispo A, Ferreira I, Rego A, Coelho I, Motta C, Prates JA, Castanheira I, Bandarra NM" year: 2023 journal: "Food Chemistry" - id: "2" pmid: "3000395" title: "Blood pressure- and lipid-lowering effect of mackerel and herring diet in patients with mild essential hypertension" authors: "Singer P, Wirth M, Voigt S, Richter-Heinrich E, Gödicke W, Berger I, Naumann E, Listing J, Hartrodt W, Taube C" year: 1985 journal: "Atherosclerosis" - id: "3" pmid: "19260945" title: "A diet enriched with mackerel (Scomber scombrus)-derived products improves the endothelial function in a senior population (Prevención de las Enfermedades Cardiovasculares: Estudio Santoña--PECES project)" authors: "de Berrazueta JR, Gómez de Berrazueta JM, Amado Señarís JA, Peña Sarabia N, Fernández Viadero C, García-Unzueta MT, Sáez de Adana M, Sanchez Ovejero CJ, Llorca J" year: 2009 journal: "European Journal of Clinical Investigation" - id: "4" pmid: "34172393" title: "Triglyceride-lowering and anti-inflammatory mechanisms of omega-3 polyunsaturated fatty acids for atherosclerotic cardiovascular risk reduction" authors: "Liu QK" year: 2021 journal: "Journal of Clinical Lipidology" - id: "5" pmid: "17267210" title: "An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D?" authors: "Lu Z, Chen TC, Zhang A, Persons KS, Kohn N, Berkowitz R, Martinello S, Holick MF" year: 2007 journal: "Journal of Steroid Biochemistry and Molecular Biology" - id: "6" pmid: "30019766" title: "Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease" authors: "Abdelhamid AS, Brown TJ, Brainard JS, Biswas P, Thorpe GC, Moore HJ, Deane KHO, Summerbell CD, Worthington HV, Song F, Hooper L" year: 2018 journal: "Cochrane Database of Systematic Reviews" --- Mackerel is one of the most nutrient-dense fish you can eat. A single 100g serving delivers 2–3 grams of EPA and DHA — more than most fish oil capsules — along with a week's worth of vitamin B12, a meaningful dose of vitamin D, and generous amounts of selenium and CoQ10. Atlantic mackerel is also low in mercury, making it safe to eat two or three times a week. Clinical trials show that a mackerel-rich diet measurably lowers triglycerides, reduces blood pressure, and improves the function of blood vessels. [1][2][3] ## What Makes Mackerel Stand Out Mackerel belongs to the SMASH group — sardines, mackerel, anchovies, salmon, and herring — the fatty fish most strongly associated with cardiovascular protection and longevity. Among this group, Atlantic mackerel (*Scomber scombrus*) and chub mackerel (*Scomber colias*) are particularly rich in omega-3 fatty acids because they spend their lives swimming in cold, deep water and feeding on krill. **Omega-3 fatty acids (EPA and DHA):** A 100g serving of Atlantic mackerel provides roughly 2–3 grams of EPA and DHA combined, exceeding the American Heart Association's recommendation of about 1g per day for cardiovascular health. These are the active long-chain omega-3s that reduce inflammation and triglycerides — distinct from the shorter-chain ALA found in flaxseed and walnuts. **Vitamin B12:** Mackerel is one of the highest food sources of B12 available. Research on chub mackerel found that B12 bioaccessibility reaches 77–83%, meaning the body absorbs and uses it efficiently. Even 15–18g of mackerel (less than one bite) can meet daily B12 requirements, and a full serving provides several days' worth. [1] **Vitamin D:** Mackerel is among a small number of foods with meaningful vitamin D content. Fish accumulate vitamin D3 in their fat, and mackerel's oily flesh makes it a reliable dietary source in populations with limited sun exposure. [5] **Selenium:** Mackerel provides selenium alongside its omega-3 content — a combination that matters for safety. Selenium binds mercury with high affinity, and when selenium is present in excess of mercury (the selenium-to-mercury molar ratio is above 1 in mackerel), the mercury is effectively neutralised before it can cause harm. This makes mackerel a genuinely safe fish to eat regularly, unlike larger predator fish such as swordfish or king mackerel. **Note on mercury:** Choose Atlantic mackerel, chub mackerel, or Spanish mackerel. Avoid king mackerel (*Scomberomorus cavalla*), which accumulates significantly more mercury due to its position at the top of the food chain. ## How the Omega-3s Work EPA and DHA lower cardiovascular risk through several complementary mechanisms. [4] In the liver, omega-3s activate PPAR-alpha receptors, increasing the oxidation of fatty acids and reducing the assembly and secretion of VLDL — the lipoprotein that carries triglycerides into the bloodstream. The result is a substantial drop in circulating triglycerides, often 20–40% with regular intake. In blood vessels, EPA and DHA promote the production of nitric oxide in endothelial cells, keeping vessels relaxed and blood pressure lower. They also shift the balance of eicosanoids away from the pro-inflammatory prostaglandin E2 and thromboxane A2 toward more anti-inflammatory resolvins and protectins. In platelets, omega-3s reduce aggregation tendency — the tendency of blood cells to clump together — which lowers clotting risk without the bleeding risk associated with pharmaceutical anticoagulants at normal dietary doses. ## Practical Use Mackerel is available fresh, frozen, smoked, and canned. Canned mackerel in water or olive oil preserves most of its omega-3 content and is among the most affordable ways to eat oily fish. Smoked mackerel is nutrient-dense but higher in sodium. Fresh mackerel deteriorates quickly and should be cooked or consumed within a day or two of purchase. Two to three servings per week (150–200g each) provides a meaningful therapeutic dose of EPA and DHA while staying within safe mercury limits for most adults. Pregnant women should choose Atlantic mackerel and confirm current advisory guidelines, as they apply stricter limits. Mackerel pairs well with acidic accompaniments — lemon, capers, pickled vegetables — which complement its oily richness. It works well pan-fried, grilled, baked, or eaten cold straight from the tin. See our [sardines page](/sardines/nutrient-dense-seafood) and [omega-3 pages](/omega-3/epa-and-dha) for related reading on fatty fish and long-chain omega-3s. ## Evidence Review ### Nutritional Composition A 2023 analysis of chub mackerel by Afonso and colleagues examined nutrient content across seasons and assessed bioaccessibility — how much the body can actually absorb — using an in vitro digestion model. [1] The study confirmed high DHA content (the most abundant fatty acid in mackerel flesh), selenium concentrations that reliably exceed mercury content on a molar basis, and B12 bioaccessibility of 77–83%. Seasonal variation was detected in fat content and fatty acid profile, with fish caught in autumn carrying higher omega-3 loads after the summer feeding period. The data support mackerel as a nutritionally dense fish with meaningfully bioavailable micronutrients. ### Blood Pressure and Lipids Singer et al. (1985) conducted a crossover trial in 14 male patients with mild essential hypertension, placing subjects on a mackerel and herring diet for two weeks within an isocaloric regimen. [2] Outcomes included significant reductions in systolic blood pressure measured both at rest and under a standardised psychophysiological stress test. Serum triglycerides, total cholesterol, and LDL were also significantly reduced. The cardiovascular effects were attributed primarily to EPA content modifying prostaglandin and thromboxane synthesis. Subsequent trials by the same German research group replicated and extended these findings, demonstrating durable effects with longer exposure and confirming that whole mackerel produced larger lipid improvements than equivalent EPA doses in capsule form — an early indication that the food matrix influences bioavailability. ### Endothelial Function De Berrazueta and colleagues (2009) conducted the PECES (Prevención de las Enfermedades Cardiovasculares: Estudio Santoña) project, enrolling 58 elderly subjects (mean age 82 years) who consumed mackerel-derived products supplying 8.82g of EPA+DHA per 100g of product. [3] The primary outcome, endothelium-dependent flow-mediated vasodilatation, improved significantly compared to baseline. This measure reflects the ability of blood vessels to dilate in response to increased blood flow — a marker of cardiovascular health that declines with age and predicts future cardiac events. Improvement in an elderly population is particularly notable given that this group typically shows the most pronounced endothelial dysfunction. ### Omega-3 Mechanisms and Cardiovascular Risk Liu (2021) reviewed the molecular and cellular mechanisms underlying omega-3 cardiovascular benefits, covering PPAR-alpha activation, suppression of NF-kB inflammatory signalling, reduced platelet aggregation, and triglyceride lowering. [4] The review addressed the apparent discrepancy between some neutral meta-analyses and the strongly positive REDUCE-IT trial (icosapent ethyl, a purified EPA preparation), concluding that dose, preparation purity, and baseline triglyceride levels all modulate the magnitude of benefit. ### Vitamin D Content Lu et al. (2007) measured vitamin D3 directly in 5 species of fish using HPLC and mass spectrometry. [5] Fish stored whole and cooked by conventional methods retained most of their vitamin D3 content. Mackerel is among the higher-ranked fish for vitamin D3 content, though absolute amounts vary considerably between individual fish and by season. The authors concluded that fatty fish remains a meaningful dietary source of vitamin D3 and can contribute substantially to requirements when consumed regularly. ### Meta-Analytic Evidence on Omega-3 and CVD A 2018 Cochrane meta-analysis by Abdelhamid et al. synthesised evidence from randomised controlled trials on omega-3 supplementation and cardiovascular outcomes. [6] Across 79 trials with over 112,000 participants, EPA and DHA supplementation reduced cardiovascular events, coronary heart disease mortality, and triglycerides. The effect was dose-dependent and more pronounced in trials using higher doses or longer durations. Mackerel, as a whole food source delivering both long-chain omega-3s and synergistic micronutrients, represents the dietary form that most naturally matches the food patterns associated with reduced cardiovascular risk in observational studies. ### Strength of Evidence The evidence that mackerel lowers triglycerides and blood pressure is consistent across multiple controlled trials and backed by clear mechanistic explanations. The cardiovascular benefit of its EPA and DHA content is among the most thoroughly studied dietary effects in medicine. Evidence for its specific contribution to endothelial function in elderly populations is smaller but directionally clear. One limitation in interpreting whole-food mackerel studies is the difficulty of isolating omega-3s from other active components (selenium, CoQ10, B12), but this is unlikely to weaken the case for eating the whole fish.