Omega-6 and total polyunsaturated fat for the primary and secondary prevention of cardiovascular disease

Replace some saturated fat with polyunsaturated fat and the heart benefits — that’s the dietary orthodoxy. This Cochrane review asks how much the randomized evidence actually delivers.

Pooling 49 trials and more than 24,000 participants followed at least a year, the answer is sobering in its modesty. Increasing polyunsaturated fat made little or no difference to overall or cardiovascular mortality, and only slightly reduced heart-disease and combined cardiovascular events, alongside a small drop in triglycerides. A real signal, but a faint one.

The practical takeaway is measured: nudging polyunsaturated fat up, particularly in place of saturated fat, offers small cardiovascular benefit — worth doing, not transformative. The resistance comes from advocates of high-saturated-fat diets and the industries behind them, who seize on exactly this modesty.

We rate the evidence solid in method but humble in result: Cochrane systematic-review rigor and a large sample, tempered by heterogeneity and small effect sizes. Its clinical significance is modest — incremental dietary guidance with no demonstrated mortality benefit, which is itself a useful corrective to overclaiming in either direction.