Investigating serum concentration profiles of orally ingested short-chain fatty acid supplements

Acetate, propionate, and butyrate are naturally-occurring short-chain fatty acids (SCFAs) derived from bacterial metabolism of dietary fibre and have been associated with numerous positive health outcomes. All three acids have been shown to offer unique physiological and metabolic effects and, therefore, could be targeted for co-ingestion as part of a nutritional/medicinal plan. However, a better understanding of the outcomes of supplementing in combination on circulating concentration profiles is necessary to confirm uptake efficacy. This study sought to investigate the acute circulating concentration profiles of acetate, propionate, and butyrate following oral supplementation. Three experimental trials were conducted including investigations to understand the impact of capsule coating on circulating concentration profiles, the effect of supplementation dose on uptake kinetics, and the outcome of a short, repeated, supplementation routine on circulating levels. Serum samples were analysed for SCFA content using a quantitative GC-MS assay. It was observed that an acid-resistant coated capsule caused a delayed and blunted blood concentration response, with the non-acid resistant trial displaying earlier and more intense peak serum concentrations. For dose comparison investigations, all SCFAs peaked within 60 min and returned to baseline concentrations by 120 min post-supplementation. A graded dose relationship was present for propionate and butyrate when considering the total circulating exposure across a 240 min monitoring period. In addition, a one-week, twice-daily, repeated supplementation protocol resulted in no changes in basal serum SCFA concentrations. Overall, these data indicate that acetate, propionate, and butyrate display relatively similar circulating concentration profiles following oral co-ingestion, adding knowledge to help inform supplementation strategies for future outcomes where acute elevation of circulating SCFAs is desired. HPMC capsules containing acetate, propionate, and butyrate salts exhibit peak serum concentrations of each short-chain fatty acid within 60 min and a return to baseline within 120 min. Seven days of repeated intake does not alter basal serum levels.