Among individuals with an elevated baseline cardiovascular risk, reducing the intake of saturated fatty acid (SFA) was associated with a lower risk of mortality, nonfatal myocardial infarction (NFMI) and stroke over five years, according to a systematic review published Dec. 16 in Annals of Internal Medicine.

Jeremy P. Steen, BHSc (Hons), et al., examined 17 randomized nutrition trials including data on 66,337 adults (mean age, 46-66 years) with or without cardiovascular disease, and assessed the effect that reducing or modifying SFA intake had on cholesterol, mortality, and major cardiovascular events. Eleven studies replaced SFA primarily with polyunsaturated fatty acid (PUFA), four with carbohydrates and one with monounsaturated fatty acid.

Results showed that evidence stratified by risk provided low to moderate certainty that reducing SFA intake may lower the incidence of all-cause mortality (risk ratio [RR], 0.96), cardiovascular mortality (RR, 0.93), NFMI (RR, 0.86), and fatal and nonfatal stroke (RR, 0.83).

Findings for participants at low baseline cardiovascular risk revealed that absolute reductions were below the thresholds of importance (five and 10 per 1,000 persons followed over five years for fatal and nonfatal outcomes, respectively); however, among those at high risk (>20-30%), the benefits were above the thresholds, suggesting there may be important absolute reductions.

Notably, the beneficial effects were greater for NFMI when SFA was replaced primarily with PUFA vs. simply reducing SFA intake (RR, 0.75; p for interaction 0.05; supported by moderate-certainty evidence).

In an accompanying editorial comment, Ramon Estruch, MD, PhD, and Rosa M. Lamuela-Raventós, DPharm, PhD, conclude that "available evidence suggests that the relationship between SFA and heart disease is more complex than previously understood." They note the link between SFA intake and health outcomes varies with baseline risk and that there are "important differences between various SFAs ... certain types may be less detrimental – or even beneficial – compared with early assumptions."