Effects of wholegrain cereal foods on plasma short chain fatty acid concentrations in individuals with the metabolic syndrome

37 Objective: Short chain fatty acids (SCFAs) derived from dietary fibre fermentation by gut 38 microbiota have been identified as one of the mechanisms behind the association between habitual 39 whole-grain intake and a lower risk of cardiometabolic diseases. The aims of the present work are: 40 (1) to evaluate whether a whole-grain wheat-based diet may increase SCFAs concentration; (2) to 41 identify possible associations between SCFAs and metabolic changes observed after the nutritional 42 intervention. 43 Research Methods & Procedures: Fifty-four subjects participated in the trial. They underwent a 44 12-week dietary intervention based on whole-grain or refined cereal products. At baseline and after 45 the intervention, glucose, insulin, triglyceride, inflammatory markers (hs-CRP, IL-1ra, IL-6 and 46 TNF-?) and SCFAs plasma concentrations were evaluated. 47 Results: After the intervention, in the whole-grain group fasting plasma propionate concentrations 48 were higher than at baseline, whereas a reduction was detected in the control group. Thence, the 49 absolute changes (end of trial minus baseline) in fasting plasma propionate concentrations were 50 significantly different between the two groups (p=0.048). The absolute changes of fasting 51 propionate correlated with cereal fibre intake (r= 0.358, p= 0.023) but no significant correlations 52 with clinical outcomes were found. However, postprandial insulin was significantly decreased in the 53 group having the absolute changes of fasting propionate concentration above the median value 54 (p=0.022 vs subjects with fasting propionate changes below the median value). 55 Conclusions: A 12 week whole-grain wheat-based diet increases fasting plasma propionate. This 56 increase correlates with the cereal fibre intake and is associated with lower postprandial insulin 57 concentrations.