High-risk patients benefit most from saturated fat changes
Reducing saturated fat shows little benefit in low-risk adults, but may reduce deaths and heart attacks in high-risk adults, especially when replaced with polyunsaturated fat.
*Systematic review of randomized trials; Level 1a (OCEBM).

Citation

Steen JP, Klatt KC, Chang Y, et al. Effect of interventions aimed at reducing or modifying saturated fat intake on cholesterol, mortality, and major cardiovascular events: a risk-stratified systematic review of randomized trials. Annals of Internal Medicine. 2026;179:242-255. doi:10.7326/ANNALS-25-02229.

Background

Advice to lower saturated fat remains debated because it clearly lowers cholesterol, but its impact on deaths and major heart and stroke events is less certain. This review focused on long-term randomized trials and reported results by baseline heart risk.

Patients

Adults (18+) with or without prior heart disease. Exclusions: acute illness, pregnancy or breastfeeding, and trials where >20% had active cancer or unrelated chronic illness.

Intervention

Diet advice and/or provided foods or oils to reduce saturated fat or replace it with other nutrients, intended duration ≥2 years.

Control

Usual diet or higher saturated fat intake.

Outcome

All-cause death, cardiovascular death, nonfatal heart attack, stroke, total cholesterol, “bad” cholesterol (LDL).

Follow-up Period

Last trial follow-up (about 4–5 years); absolute effects standardized to 5 years.

Results

Outcome Key finding
Total cholesterol Lowered by 0.34 mmol/L on average (14 trials).
“Bad” cholesterol (LDL) Lowered by 0.15 mmol/L on average (6 trials).
Nonfatal heart attack (primary) When saturated fat was replaced mainly with polyunsaturated fat: risk ratio 0.75 (6 trials); in high-risk adults, about 21 fewer events per 1000 over 5 years (number needed to treat ≈48).
Across all trials combined, effects on deaths, stroke, and nonfatal heart attack were not clearly different from no effect; estimated benefits were more meaningful in high-risk than low-risk groups.

Limitations

Many trials were older and at higher risk of bias, and diets varied widely in what replaced saturated fat and in how well participants actually changed intake. Limited data compared replacement with monounsaturated fat or protein.

Funding

None reported.

Clinical Application

For high cardiovascular risk patients, prioritize replacing saturated fat with polyunsaturated fat foods; for low-risk patients, expect minimal event reduction and focus on overall diet quality.