AUTHOR=Middlebrook India , Peacock Joe , Tinnion Daniel J. , Leach Nicholas K. , Hilton Nathan P. , Saunders Bryan , Sparks S. Andy , Mc Naughton Lars R. 

TITLE=Capsule Size Alters the Timing of Metabolic Alkalosis Following Sodium Bicarbonate Supplementation

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.634465

DOI=10.3389/fnut.2021.634465

ISSN=2296-861X

ABSTRACT=<p><bold>Introduction:</bold> Sodium bicarbonate (NaHCO<sub>3</sub>) is a well-established nutritional ergogenic aid that is typically ingested as a beverage or consumed in gelatine capsules. While capsules may delay the release of NaHCO<sub>3</sub> and reduce gastrointestinal (GI) side effects compared with a beverage, it is currently unclear whether the capsule size may influence acid–base responses and GI symptoms following supplementation.</p><p><bold>Aim:</bold> This study aims to determine the effects of NaHCO<sub>3</sub> supplementation, administered in capsules of different sizes, on acid–base responses, GI symptoms, and palatability.</p><p><bold>Methods:</bold> Ten healthy male subjects (mean ± SD: age 20 ± 2 years; height 1.80 ± 0.09 m; weight 78.0 ± 11.9 kg) underwent three testing sessions whereby 0.3 g NaHCO<sub>3</sub>/kg of body mass was consumed in either small (size 3), medium (size 0), or large (size 000) capsules. Capillary blood samples were procured pre-ingestion and every 10 min post-ingestion for 180 min. Blood samples were analyzed using a radiometer (Radiometer ABL800, Denmark) to determine blood bicarbonate concentration ([<inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>HCO</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>]) and potential hydrogen (pH). GI symptoms were measured using a questionnaire at the same timepoints, whereas palatability was recorded pre-consumption.</p><p><bold>Results:</bold> Capsule size had a significant effect on lag time (the time [<inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>HCO</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>] changed, <italic>T</italic><sub>lag</sub>) and the timing of peak blood [<inline-formula><mml:math id="M3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>HCO</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>] (<italic>T</italic><sub>max</sub>). Bicarbonate <italic>T</italic><sub>lag</sub> was significantly higher in the large-sized (28 ± 4 min) compared with the small-sized (13 ± 2 min) capsules (<italic>P</italic> = 0.009). Similarly, <italic>T</italic><sub>max</sub> was significantly lower in the small capsule (94 ± 24 min) compared with both the medium-sized (141 ± 27 min; <italic>P</italic> &lt; 0.001) and the large-sized (121 ± 29 min; <italic>P</italic> &lt; 0.001) capsules. The GI symptom scores were similar for small-sized (3 ± 3 AU), medium-sized (5 ± 3 AU), and large-sized (3 ± 3 AU) capsules, with no significant difference between symptom scores (<italic>F</italic> = 1.3, <italic>P</italic> = 0.310). Similarly, capsule size had no effect on palatability (<italic>F</italic> = 0.8, <italic>P</italic> = 0.409), with similar scores between different capsule sizes.</p><p><bold>Conclusion:</bold> Small capsule sizes led to quicker <italic>T</italic><sub>lag</sub> and <italic>T</italic><sub>max</sub> of blood [<inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>HCO</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>] concentration compared to medium and large capsules, suggesting that individuals could supplement NaHCO<sub>3</sub> in smaller capsules if they aim to increase extracellular buffering capacity more quickly.</p>