Unhealthy fats

Part 3: Interesterified fats

Trans-fatty acids are now being abandoned by many manufacturers as it has become accepted that they are harmful. Instead, a new type of fat, called interesterified fat, has been developed.

Interesterified fat is hydrogenated and then rearranged on the molecular level, a process which hardens fat in much the same way as trans-fatty acids.

But new research published in a recent issue of Nutrition & Metabolism suggests that interesterified fats may be even more unhealthy than the trans-fats they replace.[1]

The structure of each individual fat molecule is important to health as the specific location of individual fatty acids on the glycerol molecule seems to affect the metabolism of both fat and glucose.

Two key results from the study, which compared diets containing natural saturated palm oil with partially hydrogenated soybean oil and interesterified soybean oil, stood out:

Firstly, HDL levels dropped on the interesterified fat diet; and secondly, while blood glucose levels remained relatively stable for 8 hours on the palm oil and partially hydrogenated soybean oil diets, the interesterified fat diet suppressed insulin production allowing blood glucose levels to rise by an alarming 20%.

Reference
1. Sundram K, Karupaiah T, KC Hayes KC. Stearic acid-rich interesterified fat and trans-rich fat raise the LDL/HDL ratio and plasma glucose relative to palm olein in humans. Nutr Metab 2007 ; 4: 3.