Clinical question
Does the reduction of dietary saturated fat by replacing it with carbohydrate, polyunsaturated fat, monounsaturated fat and/or protein reduce the risk of death or cardiovascular disease events?
Bottom line
There was little or no effect of reducing saturated fat on all‐cause mortality (risk ratio 0.96; 95% confidence interval 0.90–1.03) or cardiovascular mortality (RR 0.95; 95% CI 0.80–1.12). There was also little or no effect of reducing saturated fats on non‐fatal myocardial infarction (RR 0.97; 95% CI 0.87–1.07) or coronary heart disease mortality (RR 0.97; 95% CI 0.82–1.16).
But evidence showed that reducing dietary saturated fat reduced the risk of combined CVD events by 21% (RR 0.79; 95% CI 0.66–0.93). The number needed to treat for an additional beneficial outcome was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~4 years for 1 person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 32.
Caveat
The quality of evidence balances the uncertainties of allocation concealment, lack of blinding, and presence of systematic differences in care and additional dietary differences between arms with the scale and consistency of the evidence across studies and across decades, despite very different designs and design flaws. For this reason, there is moderate‐quality evidence that interventions that reduce dietary saturated fat intake reduce the risk of CVD events.
Context
Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes are less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.
Cochrane Systematic Review
Hooper L et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev 2020, Issue 5. Art. No.: CD011737. DOI: 10.1002/14651858.CD011737.pub2. This review contains 15 trials with a total of 15,509 participants.
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