Fish & Seafood
What does research show about fish and seafood, eaten a few times a week in the Nordic diet?
Nordic Diet Companion gathers the fish and seafood research here — the small Nordic feeding trials and the large intake studies — including the trials where fatty fish moved one marker and left the rest unchanged.
Contents — 5 entries
- 📄 Herring Intake and Blood Lipids in Overweight Men (Crossover)
- 📄 Fatty and Lean Fish and Lipoprotein Subclasses in Heart Disease (RCT)
- 📄 Fatty and Lean Fish and Blood Pressure in Heart Disease (RCT)
- 📄 Fish Consumption and Mortality (Dose-Response Meta-Analysis)
- 📄 Fish Consumption and Cardiovascular Events in Diabetes (Swedish Cohort)
📄 Herring Intake and Blood Lipids in Overweight Men (Crossover)
Lindqvist HM, et al. — British Journal of Nutrition, 2009 · pubmed / 18634706
Nordic Diet Companion research surfaced this report because it covers a traditional Nordic fish and blood lipids. In a randomized crossover trial, 35 overweight men ate 150 grams of baked herring 5 days a week for 6 weeks versus a lean-meat reference diet, and the only significant change was a slightly higher HDL cholesterol (1.04 versus 0.99 mmol/L). LDL, total cholesterol, and the inflammation and oxidation markers did not change, and the sample was small and male-only.
What it examines: a crossover trial of herring versus lean meat on blood lipids. Why it's in the Nordic Diet Companion research index: a feeding trial of herring, a Nordic fish, and blood lipids.
📄 Fatty and Lean Fish and Lipoprotein Subclasses in Heart Disease (RCT)
Erkkilä AT, et al. — Journal of Clinical Lipidology, 2014 · pubmed / 24528693
Nordic Diet Companion research surfaced this report because it covers how fish changes the detail of blood lipids. In a randomized trial of 33 people with coronary heart disease eating at least four fish meals a week for 8 weeks, fatty fish increased the cholesterol carried in very large HDL particles but did not change the size of LDL or VLDL particles. The per-group samples were very small, so the clinical meaning of these subclass shifts is uncertain.
What it examines: a trial of fatty versus lean fish on lipoprotein subclasses in heart disease. Why it's in the Nordic Diet Companion research index: a trial of fish intake and detailed lipoprotein subclasses.
📄 Fatty and Lean Fish and Blood Pressure in Heart Disease (RCT)
Erkkilä AT, et al. — European Journal of Nutrition, 2008 · pubmed / 18665413
Nordic Diet Companion research surfaced this report because it covers whether fish lowers blood pressure. In a randomized pilot of 33 medicated coronary-heart-disease patients eating at least four fish meals a week for 8 weeks, blood pressure fell in the lean-fish group (about 3.5% systolic and 4.6% diastolic) but not in the fatty-fish group. The trial was a small pilot, and the reduction appeared with lean rather than fatty fish, against the usual expectation.
What it examines: a pilot trial of fatty versus lean fish on blood pressure. Why it's in the Nordic Diet Companion research index: a trial of fish intake and blood pressure in heart-disease patients.
📄 Fish Consumption and Mortality (Dose-Response Meta-Analysis)
Jayedi A, et al. — Public Health Nutrition, 2018 · pubmed / 29317009
Nordic Diet Companion research surfaced this report because it covers fish intake and long-term outcomes. Pooling 14 cohorts and 911,348 people, the 2018 dose-response meta-analysis found each 20 grams a day of fish was associated with slightly lower cardiovascular mortality (relative risk 0.96, 95% CI 0.94 to 0.98) and a borderline link to all-cause mortality (0.98, 95% CI 0.97 to 1.00). The all-cause association was highly variable across studies and significant mainly in Asian rather than Western populations.
What it examines: a dose-response meta-analysis of fish intake and mortality. Why it's in the Nordic Diet Companion research index: a meta-analysis of fish intake and cardiovascular and total mortality.
📄 Fish Consumption and Cardiovascular Events in Diabetes (Swedish Cohort)
Wallin A, et al. — Clinical Nutrition, 2018 · pubmed / 28185684
Nordic Diet Companion research surfaced this report because it covers fish intake in Nordic cohorts of people with diabetes. Following 2,225 Swedish adults with type 2 diabetes for up to 15 years, eating more than three fish servings a week versus three or fewer a month was associated with a lower risk of heart attack (hazard ratio 0.60, 95% CI 0.39 to 0.92) but no association with stroke (1.04) and a borderline link to total mortality. It is observational, and the benefit was specific to heart attack.
What it examines: a Swedish cohort of fish intake and cardiovascular events in type 2 diabetes. Why it's in the Nordic Diet Companion research index: a Nordic cohort of fish intake and heart events in diabetes.
All 5 sources last verified June 2026.
Frequently Asked Questions
Is fish good for your heart?
Observational studies link regular fish to slightly lower cardiovascular mortality (about 4% per 20 g/day; Jayedi, 2018) and, in Swedish adults with diabetes, lower heart-attack risk (Wallin, 2018). These are associations, not proof, and this is not medical advice.
Does fatty fish lower cholesterol or blood pressure?
The effects are small and inconsistent. Herring raised HDL but left other lipids unchanged (Lindqvist, 2009), and in one trial blood pressure fell with lean fish, not fatty fish (Erkkilä, 2008).
How much fish does the Nordic diet include?
Typically fish a few times a week. The intervention trials here used four or more fish meals weekly (Erkkilä, 2014).
Is more fish always better?
Not clearly. A meta-analysis found a U-shaped pattern for all-cause mortality and only a borderline overall link, strongest in Asian populations (Jayedi, 2018).
More in Nordic Diet Research
Educational information only — not medical advice, and not a recommendation to start, stop, or change any diet, supplement, or treatment. Talk to a qualified healthcare professional before making changes. Nordic Diet Companion and Copper Sun Content and Creative, LLC are not medical providers.