Dietary palmitic acid to oleic acid ratio modulates energy metabolism and biological rhythms in young healthy Japanese males.

The present study investigated the potential role of the composition of dietary fatty acids in the regulation of biological rhythms, such as the sleep architecture, core body temperature, and leukocyte clock gene expression, in subjects fed meals rich in palmitic acid or oleic acid.Eleven males participated in two sessions of indirect calorimetry in a whole-room metabolic chamber. In each session, subjects consumed three meals rich in palmitic acid (44.3% of total fat as palmitic acid and 42.3% as oleic acid) or oleic acid (11.7% of total fat as palmitic acid and 59.3% as oleic acid) in the metabolic chamber.The ratio of palmitic acid to oleic acid in plasma was significantly lower and fat oxidation was significantly higher during 24 h of indirect calorimetry in the session with meals rich in oleic acid than in that with meals rich in palmitic acid. The duration of slow wave sleep (SWS) was shorter, the latency of SWS was longer, and the nadir of core body temperature after bedtime was later in the session with meals rich in palmitic acid than in that with meals rich in oleic acid. The peak in CRY1 gene expression was earlier and its amplitude was higher in the session with meals rich in palmitic acid than in that with meals rich in oleic acid.In healthy young males, meals rich in palmitic acid decreased fat oxidation and disrupted biological rhythms, particularly the sleep architecture and core body temperature during sleep, more than meals rich in oleic acid.