Interesterified Oil
Interesterified oil is a semi-solid fat created by chemically or enzymatically shuffling the fatty acids within and between triglyceride molecules. By taking a liquid oil (like soybean) and a hard fat (like fully hydrogenated stearic acid) and "interesterifying" them, scientists create a fat with a specific melting point and texture. In the industry, it is positioned as a "Zero Trans Fat" solution that provides the creamy "mouthfeel" and structural stability required for puff pastries, margarines, and frostings without the regulatory baggage of trans fats.
The primary biological concern with interesterified oil is its impact on glucose metabolism and lipid transport.
Insulin Response: Human clinical trials have shown that interesterified fats can raise blood glucose levels and depressed insulin responses more significantly than even trans fats.
Lipid Rearrangement: By placing saturated fats in the sn-2 position (the middle "prong" of the triglyceride), these fats are absorbed more efficiently into the bloodstream, which may bypass some of the body's natural regulatory checks for fat absorption.
Liver Stress: There is emerging evidence that these synthetic fat structures may contribute to increased fat accumulation in the liver.