Interesterified Palm Olein (IEPalm) and Interesterified Stearic Acid-Rich Fat Blend (IEStear) Have No Adverse Effects on Insulin Resistance: A Randomized Control Trial.

Yen Ng,Augustine Ong,Miskandar Mat Sahri,Norhaizan Mohd Esa,Phooi Voon,Seng Ong,Verna Lee,Tony Ng

doi:10.3390/nu10081112

Abstract

Chemically-interesterified (CIE) fats are trans-fat free and are increasingly being used as an alternative to hydrogenated oils for food manufacturing industries to optimize their products’ characteristics and nutrient compositions. The metabolic effects of CIE fats on insulin activity, lipids, and adiposity in humans are not well established. We investigated the effects of CIE fats rich in palmitic (C16:0, IEPalm) and stearic (C18:0, IEStear) acids on insulin resistance, serum lipids, apolipoprotein concentrations, and adiposity, using C16:0-rich natural palm olein (NatPO) as the control. We designed a parallel, double-blind clinical trial. Three test fats were used to prepare daily snacks for consumption with a standard background diet over a period of 8 weeks by three groups of a total of 85 healthy, overweight adult volunteers. We measured the outcome variables at weeks 0, 6, and at the endpoint of 8. After 8 weeks, there was no significant difference in surrogate biomarkers of insulin resistance in any of the IE fat diets (IEPalm and IEStear) compared to the NatPO diet. The change in serum triacylglycerol concentrations was significantly lower with the IEStear diet, and the changes in serum leptin and body fat percentages were significantly lower in the NatPO-diet compared to the IEPalm diet. We conclude that diets containing C16:0 and C18:0-rich CIE fats do not affect markers of insulin resistance compared to a natural C16:0-rich fat (NatPO) diet. Higher amounts of saturated fatty acids (SFAs) and longer chain SFAs situated at the sn-1,3 position of the triacylglycerol (TAG) backbones resulted in less weight gain and lower changes in body fat percentage and leptin concentration to those observed in NatPO and IEStear.

Highlights

Liquid vegetable oils are traditionally solidified or “hardened” for household use by partial hydrogenation at high temperatures—a process which produces substantial amounts of trans fatty acids (TFAs) which raises serum lipids as well as being atherogenic [1,2]
We aim to investigate the effects of interesterified fats (IE) fats rich in palmitic acid or stearic acid obtained from interesterified palm olein (IEPalm) and interesterified vegetable oils blend (IEStear), respectively, on serum lipids, surrogate biomarkers of insulin resistance, and adiposity compared to native palm olein (NatPO)
The level of physical activity determined by T& Z calorie counter was not significantly different across the three test groups, we found that changes in weight and body mass index (BMI) at week 6 with IEStear and natural palm olein (NatPO) diets were significantly lowered compared with those of individuals on the IEPalm diet

Summary

Introduction

Liquid vegetable oils are traditionally solidified or “hardened” for household use by partial hydrogenation at high temperatures—a process which produces substantial amounts of trans fatty acids (TFAs) which raises serum lipids as well as being atherogenic [1,2]. With the goal of producing trans-free food products, modified fats other than partial hydrogenated fats are utilized in food products to optimize their characteristics and nutrient compositions. This can be achieved by blending, fractionation, interesterification, or full hydrogenation. By referring to National Health and Nutrition Examination Survey (NHANES) 1992–2002 intake data, 25 food categories were identified, representing 86% of total soybean oil intake and 79% of total TFA intake in the United States [4,5]

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