Oil Blends containing hydrogenated or interesterified fats: differential effects on plasma lipids.
Oil Blends containing hydrogenated or interesterified fats: differential effects on plasma lipids.
Year: 1998
Authors: M Noakes, P Clifton.
Publication Name: Am J Clin Nutr.
Publication Details: Volume 68; Page 242.
Abstract:
In recent years, there has been controversy regarding the effects of trans fatty acids (TFA) on plasma lipid levels. Although TFA have been shown to increase LDL-C and lower HDL-C, CO margarines containing moderate amounts of TFA have a serum lipid lowering effect in comparison to SFA. Interesterification, a chemical process that involves a rearrangement of FA on the triacylglycerol backbone, offers the prospect of hardening oils for use in margarines without producing TFA. The objective of this study was to determine the lipid lowering effects of margarines consisting of oils (either canola oil – CO or sunflower) plus a TFA-free hard fraction achieved through interesterification (from primarily SFA) versus a partially hydrogenated hard fraction. The effect of the two margarines were compared to butter. The authors speculated that because TFA were being replaced by SFA, there would be no difference between the oil blends with or without TFA. Thirty-eight mildly hyperlipidemic subjects (TC > 5.0 mmol/L) consumed a low-fat diet (<25% fat energy) for 2 weeks prior to being assigned to two groups. The baseline low-fat diet contained 9.5-10.4% SFA, 8.8-9.4 % MUFA (cis and TFA) and 4.3 % PUFA. Each subject consumed one experimental diet for 3 weeks in a random order. The diets contained 35% of energy as fat with 20% of energy as margarine or butter. The first experimental group (n = 18) consumed diets comprised of butter, a CO blend with TFA and TFA-free CO blend. The butter diet contained 15.5% SFA, 10.1 % MUFA (cis and TFA) and 2.8 % PUFA. The CO plus TFA diet contained 8.9% SFA, 14.2 % MUFA (cis and TFA) and 5.8 % PUFA. The TFA-free CO diet contained 8.7% SFA, 14.5 % MUFA (cis) and 6.0 % PUFA. In the second experimental group (n = 19), the diets consisted of butter, a sunflower oil blend with TFA, and TFA-free PUFA oil blend. The butter diet contained 17.7% SFA, 11.5 % MUFA (cis and TFA) and 3.1 % PUFA. The sunflower oil plus TFA diet contained 10.2% SFA, 11.3 % MUFA (cis and TFA) and 10.4 % PUFA. The TFA-free sunflower oil diet contained 10.3% SFA, 11.3 % MUFA (cis) and 10.5 % PUFA. In the CO blend, 10% TFA and 6% OA were replaced by approximately 14% SFA and a 2% increase in LA. In the sunflower blend, 10% TFA and 5% LA were replaced by a 10% increase in SFA as well as 3% and 1% increases in OA and ALA, respectively. Following the consumption of the low-fat diet and the oil blends, plasma LDL-C were not significantly different, but were significantly lower than the butter diet by 11-15%. Whereas the CO blends did not differ from each other in their effects on lipoprotein profiles, the TFA-free sunflower oil blend resulted in a significant 6% reduction in TC and LDL-C compared with the blend containing TFA. The ration of TC to HDL-C following the CO blend was significantly lower than at baseline and after the butter diet. The authors concluded that, compared with butter, TFA-free margarines containing CO may be equal to or more effective than margarines containing TFA in lowering LDL-C and that this would have a substantial effect on CHD reduction. The higher-fat oil blend diets were as effective in lowering LDL-C as the baseline low-fat diet that contained similar amounts of SFA. These results support previous observations that it is the FA composition rather than the amount of total fat that determines the LDL-C response.
