Increasing the proportion of plasma MUFA, as a result of dietaryintervention, is associated with a modest improvement in insulin sensitivity

Abstract

The effect of modifying dietary fatty acid (FA) composition on insulin sensitivity remains unclear. We aimed to investigate whether changes in plasmaphospholipid (PL) FA composition, as a result of dietary intervention, correspond with changes in insulin sensitivity. The RISCK study was a6-month randomised controlled dietary intervention study, which assessed the effect of modifying dietary fat and the glycaemic index (GI) of carbohydrateson insulin sensitivity. Total NEFA levels, fasting plasma PL FA profiles and an insulin sensitivity index (Si), derived from intravenous glucose toleranceminimal-model analysis, were available from 533 participants, all at elevated risk of type 2 diabetes. Bivariate correlations between changes in saturated PLFA (SFA), MUFA (as a percentage of total plasma NEFA) and changes in Si were assessed according to treatment group. Age, sex, ethnicity, percentagechange in body mass and change in dietary GI were controlled for. Increasing total NEFA concentration was associated with worsening Si (r−0·152;P=0·001). In the high-MUFA/low-GI diet group, change in PL-MUFA was positively and independently associated with change in Si (r0·297;P=0·002).Among MUFA, change in oleic acid (18 : 1) was most strongly correlated with change in Si (r0·266;P=0·005), as was change in minor FA 24 : 1 (r0·244;P=0·011) and 17 : 1 (r0·196;P=0·042). In the high-SFA/high-GI group, change in SFA concentration was not significantly associated with change in Si.In conclusion, increases in the proportion of plasma PL-MUFA following a high-MUFA dietary intervention were associated with improvements in insulinsensitivity.