Dietary n-3 PUFAs are inversely associated with risk of sudden cardiac death (SCD); however, little is known about other fats and SCD. Furthermore, concerns have been raised that high n-6 PUFA intake may attenuate the benefits of n-3 PUFAs.

We examined associations and selected interactions between dietary fatty acids, expressed as a proportion of total fat and SCD.

We conducted a prospective cohort study among 91,981 women aged 34-59 y from the Nurses' Health Study in 1980. Over 30 y, we documented 385 SCDs.

In multivariable models, women in the highest compared with the lowest quintile of SFA intake had an RR of SCD of 1.44 (95% CI: 1.04, 1.98). Conversely, women in the highest compared with the lowest quintile of PUFA intake had an RR of SCD of 0.57 (95% CI: 0.41, 0.78). Intakes of n-6 and n-3 PUFAs were both significantly associated with a lower risk of SCD, and n-6 PUFAs did not modify the association between n-3 PUFAs and SCD. MUFAs and trans fats were not associated with SCD risk. After further adjustment for coronary heart disease (CHD) and CHD risk factors potentially in the causal pathway, the association between PUFAs and SCD remained significant, whereas the association for SFAs was no longer significant.

Intake of PUFAs as a proportion of fat was inversely associated with SCD risk, independent of traditional CHD risk factors. These results support dietary guidelines to improve dietary fat quality by replacing intake of SFAs with n-6 and n-3 PUFAs.