Acute sodium bicarbonate loading has negligible effects on resting and exercise blood pressure but causes gastrointestinal distress.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 23746564 · doi:10.1016/j.nutres.2013.04.009
What was done
A double-blind crossover trial evaluated the hemodynamic and gastrointestinal effects of acute sodium bicarbonate ingestion. Eleven endurance-trained men and women (training 4.6 ± 0.4 sessions/week, 65 ± 6 minutes/session) completed two testing sessions in random sequence: once following sodium bicarbonate loading (300 mg/kg) and once following placebo ingestion. Blood pressure and heart rate were measured at baseline, 30 minutes post-consumption, during 20 minutes of steady-state submaximal cycling exercise, and during recovery. Gastrointestinal distress was also assessed.
What was found
Bicarbonate loading did not affect systolic blood pressure across rest, exercise, or recovery (P = .38). It produced a modest increase in diastolic blood pressure (treatment effect: +3.3 ± 1.1 mmHg, P = .01) and a higher heart rate (treatment effect: +10.1 ± 2.4 beats/min, P = .002). Global ratings of gastrointestinal distress severity on a 0–10 scale were higher with bicarbonate than placebo (5.1 ± 0.5 vs 0.5 ± 0.2, P < .0001). Among participants, 91% (10/11) experienced diarrhea, 64% experienced bloating and thirst, and 45% experienced nausea after bicarbonate loading.
Why it matters
Despite providing a large acute sodium load well above dietary reference intakes, an ergogenic dose of sodium bicarbonate causes negligible clinically meaningful changes in resting and submaximal exercise blood pressure. However, gastrointestinal side effects remain highly prevalent and limiting.
Limits
The study had a very small sample size (n = 11) limited to endurance-trained individuals, preventing generalization to untrained or hypertensive populations. It tested only a single acute dose during submaximal exercise without evaluating high-intensity performance or chronic exposure.
Cited by
- supports Oral ingestion of sodium bicarbonate frequently causes acute gastrointestinal distress.