Colonic fermentation from lactulose inhibits lipolysis in overweight subjects

One of the strategies to prevent insulin resistance is to reduce circulating free fatty acids (FFA). The aim of this study is to assess the effect of an oral lactulose load on fatty acid metabolism in overweight subjects. Eight overweight subjects received a primed constant intravenous infusion of [1-13C]acetate and of [1,1,2,3,3-2H5]glycerol for 9 h. After 3 h of tracer infusion, patients ingested 30 g lactulose, or saline solution. Arterialized blood samples were collected every 20 min. Basal plasma concentrations of acetate were similar before and between oral treatments as well as glycerol and FFA concentrations. Plasma acetate turnover was 11.4 ± 2.4 vs. 10.7 ± 1.4 μmol·kg−1·min−1 [not significant (NS)], and plasma glycerol turnover was 3.8 ± 0.4 vs. 4.8 ± 1.9 μmol·kg−1·min−1 (NS). After lactulose ingestion, acetate concentration increased twofold and then decreased to baseline. Acetate turnover rate increased to 15.5 ± 2.2 μmol·kg−1·min−1 after lactulose treatment, whereas it was unchanged after sal...