A Comparison of Sodium Citrate and Sodium Bicarbonate Ingestion: Blood Alkalosis and Gastrointestinal Symptoms

This study compared the recommended dose of sodium citrate (SC, 500 mg/kg body mass) and sodium bicarbonate (SB, 300 mg/kg body mass) for blood alkalosis (blood [HCO3−]) and gastrointestinal symptoms (GIS; number and severity). Sixteen healthy individuals ingested the supplements in a randomized, crossover design. Gelatin capsules were ingested over 15 min alongside a carbohydrate-rich meal, after which participants remained seated for forearm venous blood sample collection and completion of GIS questionnaires every 30 min for 300 min. Time-course and session value (i.e., peak and time to peak) comparisons of SC and SB supplementation were performed using linear mixed models. Peak blood [HCO3−] was similar for SC (mean 34.2, 95% confidence intervals [33.4, 35.0] mmol/L) and SB (mean 33.6, 95% confidence intervals [32.8, 34.5] mmol/L, p = .308), as was delta blood [HCO3−] (SC = 7.9 mmol/L; SB = 7.3 mmol/L, p = .478). Blood [HCO3−] was ≥6 mmol/L above baseline from 180 to 240 min postingestion for SC, significantly later than for SB (120–180 min; p < .001). GIS were mostly minor, and peaked 80–90 min postingestion for SC, and 35–50 min postingestion for SB. There were no significant differences for the number or severity of GIS reported (p > .05 for all parameters). In summary, the recommended doses of SC and SB induce similar blood alkalosis and GIS, but with a different time course.