Surprising study finds processed fats may not harm heart health

Researchers from King’s College London and Maastricht University conducted the investigation, which was published in the American Journal of Clinical Nutrition. The study focused on interesterified (IE) fats that are high in either palmitic acid (sourced from palm oil) or stearic acid (derived from other plant fats).

These fats are frequently used in place of trans fats and animal fats, both of which are known to raise the risk of heart disease.

Testing the Health Effects of Processed Fats

In the experiment, forty-seven healthy adults participated in a double-blind randomized crossover trial. This design ensured that neither participants nor researchers knew which type of fat was being consumed during each phase.

Each participant followed two separate six-week diets that included muffins and spreads made with either palmitic acid-rich fats or stearic acid-rich fats. These fats provided about 10% of the participants’ total daily energy intake.

The researchers then evaluated a range of cardiometabolic health indicators, including cholesterol, triglycerides, insulin sensitivity, liver fat levels, inflammation, and blood vessel function.

Results showed no meaningful differences between the two types of fats in blood cholesterol or triglyceride levels, including the ratio of total to HDL cholesterol, a key measure of cardiovascular risk.

The study also found no signs of harm related to inflammation, insulin resistance, liver fat accumulation, or vascular health.

“Not All Food Processing Is Bad for Us”

Professor Sarah Berry, senior author and Professor of Nutritional Sciences at King’s College London, explained: “With the current demonization of everything processed, this research highlights that not all food processing is bad for us! The process of interesterification allows the generation of hard fats in place of harmful trans fats, whilst also enabling manufacturers to reduce the saturated fat content of spreads and foods. Given the widespread use of the process of interesterification of fats and the fearmongering around food processing, this research is timely.”

The results indicate that both palmitic acid and stearic acid-rich interesterified fats, when consumed in normal dietary amounts, do not appear to raise short-term risk factors linked to heart disease.

Professor Wendy Hall, lead author and Professor of Nutritional Sciences at King’s College London, said: “Our findings provide reassuring evidence that industrially processed fats currently used in everyday foods, whether rich in palmitic or stearic acid, are unlikely to have harmful effects on cardiovascular health when consumed in amounts that people could achieve in their everyday diets. This is important given the widespread use of these fats in processed foods such as margarines, pastries, and confectionery.”

More Research Needed for Long-Term Effects

Although the six-week study was long enough to detect important changes in cholesterol and related markers, the researchers note that longer studies are needed to explore potential long-term effects.

This research was conducted jointly by King’s College London and Maastricht University and was supported by the Malaysian Palm Oil Board.