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

Tinnion, DJ ORCID: https://orcid.org/0000-0002-3116-0985, Marticorena, FM ORCID: https://orcid.org/0000-0002-8712-4975, Dobson, B ORCID: https://orcid.org/0000-0003-0413-878X, Hilton, NP ORCID: https://orcid.org/0000-0003-0204-8967, Mc Naughton, LR ORCID: https://orcid.org/0000-0002-3743-3171 and Sparks, SA ORCID: https://orcid.org/0000-0003-0910-2225 (2024) The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation. Research in Sports Medicine, 32 (5). pp. 857-870. ISSN 1543-8627

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Abstract

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 g.kg−1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07 g.kg−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 symptoms 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 performance above starting at a standardized time point where HCO3− is still elevated remains unclear.