The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation

D. J. Tinnion*, F. M. Marticorena, B. Dobson, N. P. Hilton, L. R. Mc Naughton, S. A. Sparks

*Corresponding author for this work

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Enterically coated (ENT) or delayed-release (DEL) capsules may lessen gastrointestinal symptoms (GIS) following acute sodium citrate (SC) ingestion, although the effects on blood acid-base balance are undetermined. Fourteen active males ingested 0.4−1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07−1 BM sodium chloride control (CON). Blood acid-base balance and GIS were measured for 4 h. Ingestion form had no significant effect on total GIS experienced (GEL: 2 ± 7; DEL: 1  ± 8; ENT: 1 ± 4 AU). Most (7/14) participants experienced zero symp-toms throughout. Peak GIS typically emerged ≤100 min post- ingestion, with a similar time to reach peak GIS between ingestion form (GEL: 36 ± 70; DEL: 13 ± 28; ENT: 15 ± 33 AU). Blood [HCO3−] was significantly higher with ENT versus GEL (ENT: 29.0 ± 0.8; GEL: 28.5 ± 1.1 mmol.L−1, P = 0.037). Acute ingestion of a reduced SC dose elicited minimal GIS, producing significant changes in blood [HCO3−] from rest, irrespective of ingestion form (GEL: 6.0 ± 0.9; DEL: 5.1 ± 1.0; ENT: 6.2 ± 0.8 mmol.L−1). The necessity of individualized ingestion strategies is also challenged, with sustained increases in blood [HCO3−] of ≥4 mmol.L−1 for up to 153 min highlighted. If commencing exercise at peak alkalosis augments subsequent per-formance above starting at a standardized time point where HCO3− is still elevated remains unclear.
Original languageEnglish
Pages (from-to)1-14
JournalResearch in Sports Medicine
Early online date28 Nov 2023
Publication statusPublished - 28 Nov 2023


  • Bicarbonate
  • buffering
  • fatigue
  • peripheral


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