A recent study conducted by researchers at King’s College London and Maastricht University has found that two types of industrially processed hard fats, commonly used in everyday foods such as bakery products, margarines, and spreads, are unlikely to have an adverse effect on heart health when consumed in levels that are typically found in most people’s diets.
The study focused on interesterified (IE) fats that are rich in either palmitic acid (derived from palm oil) or stearic acid (derived from other plant fats). These fats are often used by the food industry as alternatives to trans fats and animal fats, which are known to pose risks to heart health.
During the trial, forty-seven healthy adults participated in a double-blind randomized crossover study, where they followed two different diets for six weeks each. These diets included muffins and spreads made with either palmitic acid-rich fats or stearic acid-rich fats, providing around 10% of their daily energy intake. The researchers evaluated various cardiometabolic health markers such as cholesterol, triglycerides, insulin sensitivity, liver fat, inflammation, and blood vessel function.
The results of the study showed no significant differences between the two types of fats in terms of blood cholesterol or triglyceride profiles, including the ratio of total to HDL cholesterol, which is a key indicator of cardiovascular risk. Additionally, there were no adverse effects observed on inflammation, insulin resistance, liver fat, or vascular function.
Professor Sarah Berry, the senior author of the study and Professor of Nutritional Sciences at King’s College London, emphasized that not all food processing is detrimental to health. She highlighted that interesterification allows for the production of hard fats as substitutes for harmful trans fats, while also enabling manufacturers to reduce the saturated fat content of food products.
The study’s findings suggest that both palmitic acid and stearic acid-rich interesterified fats, when consumed in realistic amounts, do not increase short-term risk factors for heart disease. Professor Wendy Hall, the lead author and Professor of Nutritional Sciences at King’s College London, stressed the importance of these findings given the widespread use of these fats in processed foods like margarines, pastries, and confectionery.
While the trial duration was six weeks, sufficient to detect meaningful changes in cholesterol and other cardiovascular risk factors, further studies are needed to assess the long-term effects of consuming these processed fats. The study was a collaborative effort between King’s College London and Maastricht University.
For more information on the study, the research paper titled “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” can be accessed in The American Journal of Clinical Nutrition (DOI: 10.1016/j.ajcnut.2025.09.025).
This groundbreaking research provides reassurance that industrially processed fats, whether rich in palmitic or stearic acid, are unlikely to pose harmful effects on cardiovascular health when consumed in amounts that are typical in everyday diets. The study contributes valuable insights into the ongoing discourse surrounding food processing and its impact on heart health.
