New fats raise blood sugar.
Article Type: Report
Subject: Blood sugar (Health aspects)
Blood sugar (Research)
Insulin (Measurement)
Insulin (Health aspects)
Insulin (Research)
Trans fatty acids (Health aspects)
Trans fatty acids (Research)
Author: Klotter, Jule
Pub Date: 05/01/2009
Publication: Name: Townsend Letter Publisher: The Townsend Letter Group Audience: General; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 The Townsend Letter Group ISSN: 1940-5464
Issue: Date: May, 2009 Source Issue: 310
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: Malaysia Geographic Code: 9MALA Malaysia
Accession Number: 198715555
Full Text: Now that trans-fats are being phased out of baked goods and other processed foods, the food industry is turning to interesterified fats. These fats, like trans-fats, have a long shelf-life and a solid consistency that works well in baked goods. Interesterification replaces a polyunsaturated fat in soybean oil molecules with stearic acid. Stearic acid is a saturated fatty acid, mostly found in chocolate and cocoa butter. Unlike some saturated fats, stearic acid does not seem to raise cholesterol levels. Interesterified fats are now being used in some margarines and baked goods.


K. C. Hayes at Brandeis University (Waltham, Massachusetts) is concerned that manufacturers are swapping one harmful fat for another. Hayes conducted a preliminary study with Kalyana Sundram of the Malaysian Palm Oil Board and Tilakavati Karupaiah of the National University of Malaysia. The researchers compared the effect of three fats on blood lipids and plasma glucose in 30 human volunteers, divided into three groups. Each group ate complete, whole-food diets while getting more than 70% of their fat from one of three test fats: trans-rich partially hydrogenated soybean oil, an interesterified fat, or an unmodified saturated fat (palm olein). Researchers assessed the participants' plasma lipoproteins, fatty acid profile, fasting glucose, and insulin at the end of four weeks. Then, they randomly assigned each group to eat a different test fat for another four weeks.

Both the trans-fat and the interesterified fat significantly raised LDL/HDL ratios and fasting blood glucose compared to the natural saturated fat. Interesterified fat had a greater effect on glucose levels than the trans-fat. In addition, the interesterified fat lowered fasting insulin even more than the trans-fat did: "Fasting 4 wk insulin was 10% lower after [partially hydrogenated soybean oil] (p> 0.05) and 22% lower after [interesterified fat] at (p < 0.001) compared to [palm olein]." This study is preliminary--not conclusive. "'Whether this reflects the amount of test fat consumed, underlying genetics of the specific population examined, or some unknown factor requires further study because the apparent adverse impact on insulin metabolism is a troubling finding,'" says Hayes. He and colleagues hope that their study will spur research by others, leading to more conclusive data.

The study was partially funded by the Malaysian Palm Oil Board, and all three researchers have ties to the organization. "It's obviously a conflict of interest; I realize that and I'm not trying to disguise or hide that," Hayes said. "But I also think I know more about different kinds of fats, including palm oil, than most people in the world. I see where it's good and where it's weak, and my main goal is to try to get a better fat in the public's hands, in the public's mouth, in the public's bodies." His own preference is for mixing natural fats instead of trying to "trick nature."

New fat, same old problem with an added twist? Replacement for trans fat raises blood sugar in humans [adapted from Brandeis University press release]. Science Daily. January 18, 2007. Available at: releases/2007/01/070116131545.htm. Accessed January 30, 2009.

Sundram K, Karupaiah T, 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 [abstract]. Nutr Metab. 15 January 2007;4(3). www.nutritionandmetabolism. com/content/4/1/3/abstract. Accessed January 30, 2009.

Wood S. Risks in new fat may be similar to trans fat. Available at: Accessed January 30, 2009.

briefed by Jule Klotter
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