Polyunsaturated fats are a type of dietary fat in which the fatty acid chains contain two or more double bonds between carbon atoms (hence ‘poly’, meaning many). Unlike saturated fats (which are solid at room temperature), polyunsaturated fats are typically liquid at room temperature and are the predominant fat in most plant-based oils, including corn, safflower, sunflower, and soybean oils.
There are two main families: omega-6 fatty acids (found in vegetable oils, nuts, and seeds) and omega-3 fatty acids (found in oily fish, flaxseed, walnuts, and certain algae). Omega-3 fatty acids have particularly strong evidence for cardiovascular benefit: they reduce triglyceride levels, modestly lower blood pressure, reduce inflammation, and may decrease the risk of arrhythmias. High intake of oily fish (rich in EPA and DHA, the long-chain omega-3 fatty acids) is associated with reduced cardiovascular mortality.
Polyunsaturated fats, particularly omega-6 fats, tend to lower LDL cholesterol levels when substituted for saturated fats. Some studies have suggested that very high omega-6 intake may also modestly lower HDL cholesterol, which is less desirable. The overall balance of evidence supports replacing saturated fats with polyunsaturated and monounsaturated fats as part of a heart-healthy dietary pattern.
For cardiac arrest survivors and those at elevated cardiovascular risk, dietary patterns emphasising polyunsaturated fats from oily fish, nuts, seeds, and plant oils (such as the Mediterranean diet) are associated with better long-term cardiovascular outcomes than diets high in saturated fat.
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