Applied nutritional investigationEffects of whole-grain cereal foods on plasma short chain fatty acid concentrations in individuals with the metabolic syndrome

- Participants underwent a 12-wk dietary intervention based on whole-grain or refined cereal products.
- Higher propionate plasma levels were observed after the whole grain diet.
- The increase in fasting plasma propionate correlates with the mean intake of cereal fiber during the intervention.
- Subjects with greater changes in fasting plasma propionate between the end of the trial and baseline (above the median value) had lower postprandial insulin than subjects below the median.

ObjectiveShort chain fatty acids (SCFAs) derived from dietary fiber fermentation by gut microbiota have been identified as one of the mechanisms behind the association between habitual whole-grain intake and a lower risk of cardiometabolic diseases. The aims of the present work are: (1) to evaluate whether a whole-grain wheat-based diet may increase SCFAs concentration, and (2) to identify possible associations between SCFAs and metabolic changes observed after the nutritional intervention.MethodsFifty-four subjects participated in the trial. They underwent a 12-wk dietary intervention based on whole-grain or refined cereal products. At baseline and after the intervention, glucose, insulin, triacylglycerol, inflammatory markers (hs-CRP, IL-1 ra, IL-6, and TNF-α), and SCFAs plasma concentrations were evaluated.ResultsAfter the intervention, in the whole-grain group fasting plasma propionate concentrations were higher than at baseline, whereas a reduction was detected in the control group. The absolute changes (end of trial minus baseline) in fasting plasma propionate concentrations were significantly different between the two groups (P = 0.048). The absolute changes of fasting propionate correlated with cereal fiber intake (r = 0.358, P = 0.023), but no significant correlations with clinical outcomes were found. However, postprandial insulin was significantly decreased in the group having the absolute changes of fasting propionate concentration above the median value (P = 0.022 versus subjects with fasting propionate changes below the median value).ConclusionsA 12-wk whole-grain wheat-based diet increases fasting plasma propionate. This increase correlates with the cereal fiber intake and is associated with lower postprandial insulin concentrations.