Interaction of fish oil and a glucocorticoid on metabolic responses to an oral glucose load in healthy human subjects

Compared with saturated fat, n-3 long-chain PUFA-rich fish oil improves insulin sensitivity in rats. We studied whether n-3 long-chain PUFA could prevent insulin resistance induced by dexamethasone (a glucocorticoid) in healthy human volunteers. A group of eight subjects was studied twice after a 2d dexamethasone treatment, before and after a 3-week supplementation with fish oil (providing daily doses of 1·1g 20:5n-3 and 0·7g 22:6n-3). The subjects were studied during the basal state and over the 6h following an oral glucose load (1g/kg). Plasma glucose fluxes were traced with [6,6-2H2]glucose and [13C]glucose (naturally 13C-enriched corn glucose). Substrate oxidation was obtained from indirect calorimetry. Following fish oil supplementation, plasma glucose fluxes and substrate oxidation were maintained despite a 17% reduction (P