NEW YORK (Reuters Health) – Adopting a low-fat diet with a low glycemic index improves triglyceride levels and may increase insulin sensitivity in patients with impending metabolic syndrome. However, replacing saturated fats with monounsaturated fats has less pronounced benefits, according to findings reported in the American Journal of Clinical Nutrition online August 25.

Researchers in the UK conducted the dietary intervention RISCK trial, an acronym for the five centers participating centers — Reading, Imperial, Surrey, Cambridge, and Kings — involving 548 participants heading for metabolic syndrome. They all scored at least 4 out of a possible 13 points reflecting components of metabolic syndrome

The main aim of the trial was to see if insulin sensitivity could be improved by replacing saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs), or carbohydrates of high glycemic index (HGI) with low glycemic index (LGI). The secondary outcomes were changes in cardiovascular risk factors.

Specifically, Dr. Susan A. Jebb with MRC Human Nutrition Research in Cambridge and colleagues randomly assigned the participants to 24 weeks on a high-SFA and high glycemic index diet (HS/HGI) as a reference, or to high-MUFA and HGI (HM/HGI), HM and low glycemic index (HM/LGI), low-fat and HGI (LF/HGI), and LF and LGI (LF/LGI) diets.

At the end of the study period, the change in insulin sensitivity in the five groups was -4%, 2.1%, -3.5%, -8.6%, and 9.9%.