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Replacement of Saturated Fat with Other Nutrients

Synopsis

Some studies indicate how replacement of saturated fat with certain nutrients, such as polyunsaturated fats and carbohydrates, may impact cardiovascular health.

Highlights

• Substituting dietary saturated fat with polyunsaturated fatty acids appears to decrease the risk of coronary heart disease mortality;
• Substituting dietary saturated fat with high glycemic index carbohydrates appears to increase cardiovascular disease risk.

The Evidence

In a 2010 systematic review and meta-analysis of randomized controlled trials, it was concluded that there is strong evidence that consumption of polyunsaturated fat as a replacement for saturated fat lowers coronary heart disease risk.¹

• The pooled risk reduction for coronary heart disease events in the intervention groups compared to the controls was 19%, with a relative risk of 0.81 (95% CI: 0.70-0.95, p = 0.008);
• For each 5% energy of increased polyunsaturated fat instead of saturated fat, there was a 10% reduction in the risk of coronary heart disease, with a relative risk of 0.90 (95% CI: 0.83-0.97);
• Post-hoc secondary analyses based on study design characteristics did not substantially alter the overall pooled result for coronary heart disease events.

Another 2010 systematic review and meta-analysis of randomized controlled trials provided the following data on polyunsaturated fatty acids (PUFA) and risk of coronary heart disease:²

• For mixed n-3/n-6 PUFA diets, the pooled risk for non-fatal myocardial infarction and coronary heart disease death was significantly reduced by 22% with risk ratio 0.78 (95% CI: 0.65-0.93, p = 0.005);
• For n-6 specific PUFA diets, the pooled risk for non-fatal myocardial infarction and coronary heart disease death was increased by 13% with risk ratio 1.13 (95% CI: 0.84-1.53, p = 0.43);
• Compared to the mixed n-3/n-6 PUFA diets, the risk of non-fatal myocardial infarction and coronary heart disease death was significantly higher in the n-6 specific PUFA diets (p = 0.02);
• Substituting n-6 PUFA for trans fat and saturated fat without simultaneously increasing n-3 PUFA produced an increase in risk of death that approached statistical significance, with risk ratio 1.16 (95% CI: 0.95-1.42, p = 0.15).

A prospective cohort study of 53,644 Danish women and men aged 50 to 64 years, published in 2010, suggested that replacing saturated fatty acids with low glycemic index carbohydrates is associated with lower risk of myocardial infarction, whereas replacing saturated fatty acids with high glycemic index carbohydrates is associated with a higher risk of myocardial infarction.³

• After adjustments for confounding variables such as body mass index, smoking status and physical activity, the hazard ratio for myocardial infarction per 5% energy intake increase from carbohydrates and a concomitant lower energy intake from saturated fatty acids was 1.04 (95% CI: 0.92-1.17);
• There was a non-significant inverse association between substitution of low glycemic index carbohydrates for saturated fatty acids and risk of myocardial infarction, with a hazard ratio of 0.88 (95% CI: 0.72-1.07);
• There was no association between substitution of medium glycemic index carbohydrates for saturated fatty acids and risk of myocardial infarction, with a hazard ratio of 0.98 (95% CI: 0.80-1.21);
• There was a statistically significant positive association between substitution of high glycemic index carbohydrates for saturated fatty acids and risk of myocardial infarction, with a hazard ratio of 1.33 (95% CI: 1.08-1.64).

Conclusion

Data from literature suggests that substituting dietary saturated fat with PUFA decreases the risk of coronary heart disease death. However, replacing saturated fat with high glycemic index carbohydrates appears to increase the risk of cardiovascular disease.

Additional randomized controlled trials on the replacement of saturated fat with other types of fats or macronutrients are needed to provide more definitive answers.

For more information:

• Saturated Fat and Cardiovascular Disease
• Saturated Fat and Cardiovascular Disease Risk Factors

Keywords: cardiovascular disease, coronary heart disease, dietary factors, saturated fat, stroke, trans fat

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