Giving up butter does not always reduce the risk of heart problems.
Reducing the intake of saturated fats is associated with a decrease in mortality and the risk of cardiovascular diseases, but this effect mainly manifests in individuals with a high cardiovascular risk. This conclusion was reached by the authors of a systematic review of 17 randomized clinical trials published in the Annals of Internal Medicine (AIM).
The researchers analyzed data from 66,337 participants who were followed for at least two years. The studies compared either a reduction in the proportion of saturated fats in the diet or their replacement with other energy sources. Overall, reducing saturated fats led to a decrease in total cholesterol and low-density lipoprotein levels; however, the clinically significant effect depended on the patients' baseline risk.
In individuals from the high-risk group, reducing saturated fats was associated with a decrease in overall and cardiovascular mortality, as well as a lower number of heart attacks and strokes. The most pronounced effect was observed when saturated fats were replaced with polyunsaturated fats rather than simply reducing their quantity.
Saturated fats are found, in particular, in butter, fatty dairy products, red meat, and sausages, while polyunsaturated fats are found in vegetable oils, nuts, seeds, and fatty fish. Replacing one type of fat with another, as the analysis showed, provided a greater protective effect than merely reducing caloric intake.
At the same time, in individuals with low and moderate cardiovascular risk, limiting saturated fats for about five years was not associated with a decrease in the number of heart attacks, strokes, or deaths, despite improvements in blood lipid profiles. The authors note that such results indicate the need for more personalized dietary recommendations considering individual risk levels.
