Volume 88, Issue 6, December (2002), pp. 635-640 © The Author 2002
doi:10.1079/BJN2002729

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Acute effects of meal fatty acid composition on insulin sensitivity in healthy post-menopausal women

M. D. Robertson¹, K. G. Jackson², B. A. Fielding¹, C. M. Williams², K. N. Frayn¹
Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX2 6HE, UK
²Hugh Sinclair Unit for Human Nutrition, School of Food Biosciences, University of Reading, Reading RG6 6AP, UK

 (Received 27 March 2002–Revised 11 July 2002–Accepted 11 August 2002)

Postprandial plasma insulin concentrations after a single high-fat meal may be modified by the presence of specific fatty acids although the effects of sequential meal ingestion are unknown. The aim of the present study was to examine the effects of altering the fatty acid composition in a single mixed fat–carbohydrate meal on glucose metabolism and insulin sensitivity of a second meal eaten 5 h later. Insulin sensitivity was assessed using a minimal model approach. Ten healthy post-menopausal women underwent four two-meal studies in random order. A high-fat breakfast (40 g fat) where the fatty acid composition was predominantly saturated fatty acids (SFA), n-6 polyunsaturated fatty acids (PUFA), long-chain n-3 PUFA or monounsaturated fatty acids (MUFA) was followed 5 h later by a low-fat, high-carbohydrate lunch (5·7 g fat), which was identical in all four studies. The plasma insulin response was significantly higher following the SFA meal than the other meals after both breakfast and lunch (P<0·006) although there was no effect of breakfast fatty acid composition on plasma glucose concentrations. Postprandial insulin sensitivity (S_I(Oral)) was assessed for 180 min after each meal. S_I(Oral) was significantly lower after lunch than after breakfast for all four test meals (P=0·019) following the same rank order (SFA < n-6 PUFA < n-3 PUFA < MUFA) for each meal. The present study demonstrates that a single meal rich in SFA reduces postprandial insulin sensitivity with ‘carry-over’ effects for the next meal.

Keywords:
Fatty acids: Postprandial metabolism: Insulin sensitivity: Post-menopausal women