Oily fish carries omega-3 fats your heart uses, and eating it once or twice a week is linked to fewer deaths from heart disease. You do not need daily portions to get there. Tinned and frozen fish count fully.
A JAMA review weighing decades of evidence concluded that modest fish intake of one to two servings a week, particularly oily species, is associated with a 36 percent lower risk of coronary death and 17 percent lower total mortality, and judged the heart benefit to outweigh contaminant risks for most people (Mozaffarian and Rimm, 2006). A later dose-response meta-analysis of prospective cohorts found cardiovascular mortality falling as fish intake rises, with the curve flattening at moderate amounts (Jayedi et al., 2018). The same JAMA review maps the exception clearly: people who are or may become pregnant should avoid the four highest-mercury species. This grades moderate because almost all of it is observational, the disappointing randomised trials tested fish-oil capsules rather than fish, and people who eat fish differ from people who do not in ways studies struggle to strip out.
Doing it: Eat two servings a week and make at least one of them oily: salmon, sardines, mackerel or herring. Small cold-water species are cheap and low in mercury. If you are pregnant or planning pregnancy, skip shark, swordfish, king mackerel and tilefish.
Who it suits: Nearly everyone who enjoys it; people with existing heart disease can ask their GP whether a higher omega-3 intake makes sense in their case
Sources
- Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA 2006.
- Jayedi A, et al. Fish consumption and risk of all-cause and cardiovascular mortality: a dose-response meta-analysis. Public Health Nutr 2018.
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