Oral sodium lactate ingestion does not increase blood lactate concentrations and is accompanied by moderate-to-severe gastrointestinal side effects

Lactate has diverse roles in biology and has been implicated in the control of energy intake. A variety of methods (i.e., exercise, ingestion, and infusion) have been used to study its effects on different metabolic outcomes and the original intent of this project was to explore the effect of oral sodium lactate (Na-Lactate) ingestion on appetite regulation. During piloting, we were unable to show that Na-Lactate could increase blood lactate concentrations; thus, the purpose of this brief report is to highlight that oral Na-Lactate ingestion is not an effective method to study lactate metabolism. Five male participants (26 ± 3 yr, 82.4 ± 3.8 kg, 25.4 ± 1.6 kg·m^-2) completed 15 experimental sessions where Na-Lactate solutions were consumed with the assessment of blood lactate preingestion, 30-min, 45-min, and 60-min postingestion. Oral Na-Lactate ingestion did not increase blood lactate concentrations (Pre: 0.9 ± 0.2; 30 min: 1.2 ± 0.7; 45 min: 1.0 ± 0.5; 60 min: 0.9 ± 0.4 mmol·L^-1). In addition, there were moderate-to-severe gastrointestinal (GI) side effects (e.g., vomiting and diarrhea) following ingestion. Altogether, our data suggest that oral ingestion of Na-Lactate is not an effective method for studying lactate's role in metabolism as it did not increase blood lactate concentrations and was accompanied by problematic GI side effects.<b>NEW & NOTEWORTHY</b> Lactate has diverse roles in physiology, and a variety of methods have been used to explore its effects on metabolism. Here, we explored whether oral sodium lactate (Na-Lactate) ingestion could increase blood lactate concentrations. Oral Na-Lactate ingestion using a variety of dosing protocols did not increase blood lactate concentrations and was coupled with gastrointestinal issues. These results demonstrate that oral ingestion of Na-Lactate is not an effective method for studying lactate's role in metabolism.