Saturated Fat Reduction: Mortality Benefit Limited to High-Risk Individuals, Claims Study
Canada: A meta-analysis of randomized trials has found that reducing saturated fat intake was associated with lower mortality only in individuals at high cardiovascular risk. For those at low to intermediate risk, cutting or replacing saturated fats provided little to no benefit over five years.
These findings, published in Annals of Internal Medicine, suggest that long-standing concerns about saturated fat intake and heart disease may have been overstated for many people, adding to the ongoing controversy surrounding dietary saturated fats.
The findings are from a risk-stratified systematic review led by Jeremy P. Steen of the Institute of Health Policy, Management and Evaluation at the Dalla Lana School of Public Health, University of Toronto, and colleagues. The researchers sought to clarify inconsistent dietary guidance by evaluating randomized clinical trials that examined whether reducing or modifying saturated fat intake influences cholesterol levels, mortality, and major cardiovascular outcomes.
To address the ongoing debate, the investigators conducted a comprehensive search of MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from database inception through July 2025. The review included 17 randomized trials comprising more than 66,000 adult participants, both with and without established cardiovascular disease. All included studies assessed dietary interventions aimed at lowering saturated fat intake or replacing it with other macronutrients.
The review revealed the following notable findings:
- Reducing saturated fat intake was associated with small reductions in mortality, myocardial infarction, and stroke.
- The overall certainty of evidence was low to moderate, with modest relative risk reductions.
- Benefits varied by baseline cardiovascular risk.
- In low-risk individuals, absolute benefits were minimal and not clinically meaningful over five years.
- Saturated fat reduction did not significantly lower deaths or cardiovascular events in low-risk populations.
- In high-risk individuals, meaningful reductions in mortality and major cardiovascular events were observed.
- The strongest benefit was seen for nonfatal myocardial infarction when saturated fat was replaced with polyunsaturated fat.
The authors emphasized that not all dietary substitutions are equal. While replacing saturated fat with polyunsaturated fat appeared beneficial, data were limited regarding substitution with monounsaturated fats or protein. Additionally, the included trials varied widely in how effectively they reduced saturated fat intake, the specific replacement macronutrients used, and whether other dietary changes were implemented alongside fat modification.
Several limitations were acknowledged. The heterogeneity of dietary interventions and limited data for certain substitutions introduce uncertainty, and newer, well-designed trials are needed to refine recommendations. Nonetheless, the findings highlight the importance of tailoring dietary advice based on an individual’s cardiovascular risk profile rather than adopting a one-size-fits-all approach.
"Overall, this systematic review suggests that reducing saturated fat intake may be most relevant for individuals at high cardiovascular risk, particularly when replaced with polyunsaturated fats. For those at lower risk, the benefits appear modest, reinforcing the need for personalized nutrition guidance grounded in overall risk assessment rather than universal dietary restriction," the authors concluded.
Reference:
Steen JP, Klatt KC, Chang Y, Guyatt GH, Zhu H, Swierz MJ, Storman D, Sun M, Zhao Y, Ge L, Thabane L, Ghosh NR, Karam G, Alonso-Coello P, Bala MM, Johnston BC. 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. Ann Intern Med. 2025 Dec 16. doi: 10.7326/ANNALS-25-02229. Epub ahead of print. PMID: 41397264.
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