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Cited by 61Cardiovascular and exercise physiologyBlood Pressure and Hypertension StudiesSodium Intake and Health

Acute sodium bicarbonate loading has negligible effects on resting and exercise blood pressure but causes gastrointestinal distress

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Kahle, Laura E., Kelly, Patrick V., Eliot, Kathrin A., Weiss, Edward P.·2013·Nutrition Research
DOI 10.1016/j.nutres.2013.04.009PMC PMC3680785
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Abstract

Oral ingestion of sodium bicarbonate (bicarbonate loading) has acute ergogenic effects on short-duration, high-intensity exercise. Because sodium bicarbonate is 27% sodium, ergogenic doses (ie, 300 mg∙kg⁻¹) result in sodium intakes well above the Dietary Reference Intakes upper limit of 2300 mg/day. Therefore, it is conceivable that bicarbonate loading could have hypertensive effects. Therefore, we performed a double-blind crossover trial to evaluate the hypothesis that bicarbonate loading increases resting and exercise blood pressure (BP). A secondary hypothesis was that bicarbonate loading causes gastrointestinal distress. Eleven endurance-trained men and women (exercise frequency, 4.6 ± 0.4 sessions/wk; duration, 65 ± 6 min/session) underwent testing on two occasions in random sequence: once after bicarbonate loading (300 mg∙kg⁻¹) and once after placebo ingestion. BP and heart rate were measured before bicarbonate or placebo consumption, 30 minutes after consumption, during 20 min of steady state submaximal cycling exercise, and during recovery. Bicarbonate loading did not affect systolic BP during rest, exercise, or recovery (P = .38 for main treatment effect). However, it resulted in modestly higher diastolic BP (main treatment effect, +3.3 ± 1.1 mmHg, P = .01) and higher heart rate (main treatment effect, +10.1 ± 2.4 beats per minute, P = .002). Global ratings of gastrointestinal distress severity (0-10 scale) were greater after bicarbonate ingestion (5.1 ± 0.5 vs 0.5 ± 0.2, P < .0001). Furthermore, 10 of the 11 subjects (91%) experienced diarrhea, 64% experience bloating and thirst, and 45% experienced nausea after bicarbonate loading. In conclusion, although a single, ergogenic dose of sodium bicarbonate does not appear to have acute, clinically important effects on resting or exercise BP, it does cause substantial gastrointestinal distress.

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Crossref · 10.1016/j.nutres.2013.04.009

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  • The accumulation of CO2 in the stomach, resulting from supplementation with sodium bicarbonate, may cause bloating, nausea, vomiting, and abdominal pain.

    “The accumulation of CO2 in the stomach, resulting from supplementation with sodium bicarbonate, may cause bloating, nausea, vomiting, and abdominal pain (Kahle et al., 2013).”

    From Acute enteric-coated sodium bicarbonate has negligible effect on anaerobic performance but affects metabolomics and attenuates the gastrointestinal response (2022) · cites this paper as Kahle et al., 2013

    The Abstract reports bloating and nausea after sodium bicarbonate loading, and the Methods list vomiting and cramping among symptoms participants were asked to report. However, the Discussion says the reason for gastrointestinal distress is unclear and does not attribute it to CO2 accumulating in the stomach; the supplied results also do not establish vomiting or abdominal pain as observed outcomes. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • Gastrointestinal symptoms likely arise due to production of carbon dioxide when bicarbonate and stomach acid react, causing bloating and belching.

    “These GIS likely arise due to production of carbon dioxide (CO2) when bicarbonate and stomach acid react, causing bloating and belching, and from shifts in extracellular fluid into the intestines due to an increased osmotic sodium load (de Oliveira et al. 2018; Kahle et al. 2013).”

    From Gastrointestinal Symptoms Associated With Sodium Bicarbonate Supplementation Protocols: A Systematic Review (2026) · cites this paper as Kahle et al. 2013

    The Results (section 3.d; page unavailable) report bloating after bicarbonate loading, and the Discussion (section 4; page unavailable) proposes that an osmotic load shifts fluid into the intestines and contributes to gastrointestinal distress. Our copy does not attribute symptoms to CO2 produced by a reaction with stomach acid or report belching. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • 21 of 35 studies reported statistically greater GIS in some capacity (e.g., aggregate total, severity) with sodium bicarbonate than with comparison conditions.

    “In terms of GIS, 21 of 35 studies reported statistically greater GIS in some capacity (e.g., aggregate total, severity) with sodium bicarbonate than with comparison conditions”

    From Gastrointestinal Symptoms Associated With Sodium Bicarbonate Supplementation Protocols: A Systematic Review (2026) · cites this paper as Kahle et al. 2013

    The Results section (Gastrointestinal Distress; page unavailable) reports significantly greater GI-distress severity after sodium bicarbonate than after placebo in this trial. The paper does not report a tally of 21 out of 35 studies, so it supports an example of the finding, not the claimed count. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • Gastrointestinal symptoms likely arise from shifts in extracellular fluid into the intestines due to an increased osmotic sodium load.

    “These GIS likely arise due to production of carbon dioxide (CO2) when bicarbonate and stomach acid react, causing bloating and belching, and from shifts in extracellular fluid into the intestines due to an increased osmotic sodium load (de Oliveira et al. 2018; Kahle et al. 2013).”

    From Gastrointestinal Symptoms Associated With Sodium Bicarbonate Supplementation Protocols: A Systematic Review (2026) · cites this paper as Kahle et al. 2013

  • Caffeine improves the use of muscle glycogen during exercise.

    “and improves the use of muscle glycogen during exercise [15]”

    From Dietary and Ergogenic Supplementation to Improve Elite Soccer Players’ Performance (2021) · cites this paper as [15]

    The Introduction discusses sodium bicarbonate’s effects on exercise, not caffeine’s effects on muscle glycogen. Searches for caffeine and glycogen utilization found only a caffeine-related study title in the References; no passage in our copy addresses the claimed effect. (LLM, conf=0.77)

    Experimental — accuracy not yet measured

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  1. [10]PubChem http://pubchem.ncbi.nlm.nih.gov/ Accessed March 26, 2013

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Authors
Kahle, L. E., Kelly, P. V., Eliot, K. A., & Weiss, E. P.
Affiliations
Saint Louis University (US)
Corresponding author
Weiss, Edward P.
Venue
Nutrition Research
Publisher
Elsevier BV
Published
2013-06
Volume
33
Issue
6
Pages
479-486
ISSN
0271-5317 (ISSN-L)
DOI
10.1016/j.nutres.2013.04.009
PMC
PMC3680785
OpenAlex
W2049845354
Cited by
61
References
60
Citations by year
2026: 5 · 2025: 3 · 2024: 9 · 2023: 3 · 2022: 4 · 2021: 10 · 2020: 10 · 2019: 5 · 2018: 7 · 2017: 1 · 2016: 2 · 2015: 2
FWCI
3.15
Type
journal article
Language
en
Open access
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Nutrition Research (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Saint Louis University
  • National Institute of Diabetes and Digestive and Kidney Diseases (K01DK080886)
Topics
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Blood Pressure and Hypertension Studies
  • Health Sciences › Nursing › Nutrition and Dietetics › Sodium Intake and Health
Keywords
sodium bicarbonate, blood pressure, blood pressure response to exercise, sodium intake, gastrointestinal distress, heart rate, endurance athletes, ergogenic aids, diarrhea, bloating
MeSH terms
Adult, Bicycling, Blood Pressure, Dose-Response Relationship, Drug, Double-Blind Method, Female, Gastrointestinal Diseases, Heart Rate, Humans, Male, Nausea, Oxygen Consumption, Physical Endurance, Rest, Sodium, Exercise, Sodium Bicarbonate, Cross-Over Studies, Young Adult

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