What is exogenous lactate?
Exogenous lactate is lactate provided to the body from an external source, in contrast to the lactate the body produces internally. See also our brand pillar, What is ExoLactate?
How lactate works in the body
Lactate is continuously produced and consumed across tissues. It can be oxidised for energy, converted toward glucose, and act as a signalling molecule — far from the inert waste product it was once considered.
Endogenous vs exogenous lactate
The key difference is origin: internal production versus external supply. This affects how and when lactate becomes available, and is central to research on supplementation.
Lactate as an energy substrate
Tissues including skeletal muscle, the heart and the brain can oxidise lactate. During exercise, much of the lactate produced is used rather than discarded — evidence that lactate is a real fuel.
Lactate shuttle theory
The lactate shuttle describes how lactate moves between and within cells to be used as fuel or as a building block. It provides the theoretical foundation for interest in exogenous lactate. Read our explainer: the lactate shuttle explained.
Oral lactate supplementation
Oral lactate supplementation is an emerging research area. Human studies have examined acute dosing and outcomes such as acid–base balance, metabolic responses and gut tolerance. See: what human studies show.
Evidence in humans
The human evidence base is small and largely acute. Some trials have explored oral lactate in cycling contexts. Findings are preliminary and require replication before firm conclusions.
Evidence in animal models
Mechanistic and animal studies — including quantitative tracing work — support lactate's role as a major circulating fuel. Translating these findings to exercising humans requires care.
Performance applications
Potential applications being studied include endurance fuelling, recovery and metabolic flexibility. These remain areas of emerging evidence, not established practice.
Safety and limitations
Tolerance and safety are part of ongoing research; some studies note effects on gastric emptying and appetite. The overall evidence base is limited, and exogenous lactate should be regarded as a promising but unproven strategy that requires further research.
References
- Brooks, G. A. The Science and Translation of Lactate Shuttle Theory. Cell Metabolism (2018).
- Hui, S. et al. Quantitative Fluxomics of Circulating Metabolites. Cell Metabolism (2020).
- Bordoli, C. et al. Effects of Oral Lactate Supplementation on Acid–Base Balance and Prolonged High-Intensity Interval Cycling Performance.
- Pedersen, H. et al. Oral lactate slows gastric emptying and suppresses appetite in young males.
Frequently asked questions
What is exogenous lactate?
Exogenous lactate is lactate supplied to the body from an external source, such as an ingested supplement, rather than produced internally during metabolism.
How is exogenous lactate different from endogenous lactate?
Endogenous lactate is generated by the body, especially during intense exercise. Exogenous lactate is introduced from outside. The two may differ in their timing, concentration profile and how the body processes them.
Can the body use ingested lactate as fuel?
Lactate is an oxidisable substrate that multiple tissues can use. Whether ingested lactate meaningfully contributes to fuelling during exercise is an emerging research area that requires further study.
Is oral lactate supplementation proven?
No. Oral lactate supplementation is an emerging research area with a small, mostly acute human evidence base. It should not be considered an established or proven strategy.