Resistant Potato Starch Supplementation Reduces Serum Free Fatty Acid Levels and Influences Bile Acid Metabolism.

: Resistant starches, such as high-amylose maize starch and resistant potato starch (RPS), have prebiotic effects that are linked to improved metabolism at >15 g/day, but the effects at lower doses have not been reported. : We performed an exploratory post hoc analysis of free fatty acids (FFAs), bile acids (BAs), and ketone bodies in serum previously collected from a randomized, double-blind, placebo-controlled clinical trial evaluating the effects of one- and four-week consumption of 3.5 g/day RPS versus a placebo using two-way ANOVA adjusted by pFDR. Associations between week 4 changes in FFAs, BAs, and ketone bodies were assessed by Pearson's correlations. : RPS consumption reduced total FFAs relative to the placebo, including multiple unsaturated FFAs and octanedioic acid, with reductions in taurine- and glycine-conjugated secondary BAs also detected ( < 0.05). No changes in ketone bodies were observed ( > 0.05). Changes in 7-ketodeoxycholic acid ( = -0.595) and glycolithocholic acid ( = -0.471) were inversely correlated with treatment-induced reductions in FFAs for RPS but not the placebo, suggesting the effects were from the prebiotic. Shifts in β-hydroxybutyrate were further correlated with FFA changes in both treatments ( < 0.05). : These findings demonstrate that low doses of RPS positively influence fatty acid metabolism in humans, reducing circulating levels of FFA and conjugated BAs.