A Novel Ingestion Strategy for Sodium Bicarbonate Supplementation in a Delayed-Release Form: a Randomised Crossover Study in Trained Males

Abstract

Background: Sodium bicarbonate (NaHCO₃) is a well-established nutritional ergogenic aid, though gastrointestinal (GI) distress is a common side-effect. Delayed-release NaHCO₃ may alleviate GI symptoms and enhance bicarbonate bioavailability following oral ingestion, although this has yet to be confirmed.

Methods: In a randomised crossover design, pharmacokinetic responses and acid-base status were compared following two forms of NaHCO₃, as were GI symptoms. Twelve trained healthy males (mean ± SD age 25.8 ± 4.5 years, maximal oxygen uptake ([Formula: see text]) 58.9 ± 10.9 mL kg min^-1, height 1.8 ± 0.1 m, body mass 82.3 ± 11.1 kg, fat-free mass 72.3 ± 10.0 kg) underwent a control (CON) condition and two experimental conditions: 300 mg kg^-1 body mass NaHCO₃ ingested as an aqueous solution (SOL) and encased in delayed-release capsules (CAP). Blood bicarbonate concentration, pH and base excess (BE) were measured in all conditions over 180 min, as were subjective GI symptom scores.

Results: Incidences of GI symptoms and overall severity were significantly lower (mean difference = 45.1%, P < 0.0005 and 47.5%, P < 0.0005 for incidences and severity, respectively) with the CAP than with the SOL. Symptoms displayed increases at 40 to 80 min post-ingestion with the SOL that were negated with CAP (P < 0.05). Time to reach peak bicarbonate concentration, pH and BE were significantly longer with CAP than with the SOL.

Conclusions: In summary, CAP can mitigate GI symptoms induced with SOL and should be ingested earlier to induce similar acid-base changes. Furthermore, CAP may be more ergogenic in those who experience severe GI distress with SOL, although this warrants further investigation.

Keywords: Acid-base balance; Bioavailability; Exercise-induced fatigue; Extracellular buffer.

Fig. 1

Incidence (a) and mean (±SD) severity (b) of GI symptoms. The asterisk denotes significant difference between SOL and CAP conditions (P < 0.05)

Fig. 2

Mean (± SD) blood bicarbonate concentrations. The asterisk denotes significant difference between SOL and CAP conditions (P < 0.05)

Fig. 3

Individual changes in blood bicarbonate concentration between conditions (SOL and CAP)

Fig. 4

Mean (± SD) pH (a) and BE (b) responses. The asterisk denotes significant difference between SOL and CAP conditions (P < 0.05)