Summary
For decades, we've been told that eating foods high in saturated fat — like butter, red meat, and cheese — leads to heart disease. This study set out to test whether the science actually backs that up.
Researchers reviewed 21 large, long-term studies that tracked the diets and health outcomes of nearly 348,000 people over many years. They combined all the data to look for a clear link between how much saturated fat people ate and their risk of heart disease, stroke, or other cardiovascular problems.
What they found: There was no significant association between saturated fat intake and an increased risk of heart disease or stroke. In other words, the data from these large studies did not support the idea that eating saturated fat directly causes cardiovascular disease.
The researchers do note an important nuance: what matters is not just how much saturated fat you eat, but what you replace it with. Swapping saturated fat for refined carbohydrates, for example, may not provide any heart health benefit.
Bottom line: This study challenges the long-held belief that saturated fat is a direct cause of heart disease, suggesting the relationship between diet and cardiovascular health is more complex than previously thought.
PMID: 20071648
PMCID: PMC2824152
DOI: 10.3945/ajcn.2009.27725
Abstract
Background: A reduction in dietary saturated fat has generally been thought to improve cardiovascular health.
Objective: The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies.
Design: Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD.
Results: During 5-23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results.
Conclusions: A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.