Postprandial effects of a meal low in sulfur amino acids and high in polyunsaturated fatty acids compared to a meal high in sulfur amino acids and saturated fatty acids on stearoyl CoA-desaturase indices and plasma sulfur amino acids: a pilot study

Objective The sulfur amino acid (SAA) cysteine is positively related, whereas polyunsaturated fatty acids (PUFAs) are inversely related to activity of the lipogenic enzyme stearoyl-CoA desaturase (SCD). High SCD activity promotes obesity in animals, and plasma activity indices positively associates with fat mass in humans. SCD may thus be a target for dietary intervention with SAA restriction and PUFA enrichment with unknown potential benefits for body composition. We randomized ten healthy individuals to a meal restricted in SAAs and enriched with PUFAs (Cys/Met low + PUFA) (n = 5) or a meal enriched in SAA and saturated fatty acids (Cys/Met high + SFA) (n = 5). We measured plasma SCD activity indices (SCD16 and SCD18) and SAAs response hourly from baseline and up to 4 h postprandial. Results SCD16 was unchanged whereas SCD18 tended to increase in the Cys/Met low + PUFA compared to the Cys/Met high + SFA group (p time*group interaction = 0.08). Plasma concentrations of total cysteine fractions including free and reduced cysteine decreased in the Cys/Met low + PUFA compared to the Cys/Met high + SFA group (both p time*group interaction < 0.001). In conclusion, a meal low in SAA but high in PUFAs reduced plasma cysteine fractions but not SCD activity indices. This pilot study can be useful for the design and diet composition of future dietary interventions that targets SCD and SAA. Trial registration ClinicalTrials.gov: NCT02647970, registration date: 6 January 2016