Researchers found that commonly used processed fats made from palm and plant oils do not raise heart disease risks when eaten in normal dietary amounts.
Two kinds of processed hard fats commonly found in foods like baked goods, margarines, and spreads appear to have little effect on heart health when eaten in typical amounts.
Researchers from King’s College London and Maastricht University led the study, which was published in the American Journal of Clinical Nutrition. The investigation focused on interesterified (IE) fats containing either palmitic acid (from palm oil) or stearic acid (from other plant fats).
These fats are frequently used by manufacturers as replacements for traditional hard fats such as trans fats and animal fats, both of which are known to pose risks to cardiovascular health.
The Study Design
In the trial, forty-seven healthy adults took part in a double-blind randomized crossover trial, meaning neither the participants nor the researchers knew which type of fat was being tested during the study period. Each person followed two different diets for six weeks each, which included muffins and spreads made with either palmitic acid-rich fats or stearic acid-rich fats, providing around 10% of their daily energy intake.
Researchers assessed a comprehensive set of cardiometabolic health markers, including cholesterol, triglycerides, insulin sensitivity, liver fat, inflammation, and blood vessel function.
The findings showed no significant differences between the two fats in blood cholesterol or triglyceride profiles, including the ratio of total to HDL cholesterol, a key indicator of cardiovascular risk.
The study also found no adverse effects on inflammation, insulin resistance, liver fat, or vascular function.
Professor Sarah Berry, senior author and Professor of Nutritional Sciences at King’s College London, said: “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.”
Implications for Public Health
The results suggest that both palmitic acid and stearic acid-rich interesterified fats, when consumed in feasible amounts, do not increase short-term risk factors for 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.”
While the trial lasted six weeks, which is sufficient to detect meaningful changes in cholesterol and other cardiovascular risk factors, further studies are needed to evaluate longer-term effects.
Reference: “The effects of consumption of interesterified fats rich in palmitic acid compared with stearic acid on intermediary markers of cardiometabolic disease risk: a randomized controlled trial in healthy adults” by Wendy L Hall, Eleanor Wood, Peter J Joris, Harry A Smith, Alice Creedon, Tyler Maher, Johanna H Bruce, Ronald P Mensink and Sarah E Berry, 18 September 2025, The American Journal of Clinical Nutrition.
DOI: 10.1016/j.ajcnut.2025.09.025
The study was a collaboration between King’s College London and Maastricht University and was funded by the Malaysian Palm Oil Board.
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2 Comments
“…funded by the Malaysian Palm Oil Board”. That’s no surprise.
There is the assumption that the baked products used in this study are all the same taste and texture quality using these two fats. Probably not the case.
It is also questionable that they only studied this for 6 weeks. There is no proof that 6 weeks is enough time to see differences. And they make this assumption of “normal dietary amounts”. Normal? For whom? It also raises the question of effects from eating greater than normal amounts.
In the real world, people eat the same foods for more than 6 weeks, and they often pig out on fats. Clearly, this study was limited by its bias to support its funding source.
I didn’t even need to read to the bottom of the article to guess that this study was funded by the palm oil industry. It’s almost as bad as the recent one funded by meat producers that showed red meat was actually good for you.
I wish Frau Hossenfelder would report on some of these “studies” as well as just physics-adjacent things.