Mark P Funnell, Loris A Juett, Kirsty M Reynolds, Drusus A Johnson, Ruth M James, Stephen A Mears, Samuel N Cheuvront, Robert W Kenefick, Lewis J James
Journal: European journal of nutrition 2024;63(4):1125-1137
PMID: 38349552
Rapid gastric emptying and intestinal absorption of ingested fluid is essential for quickly replacing fluid losses incurred during exercise, heat stress and illness. The constituent solutes of a beverage significantly affect the gastric emptying rate and intestinal absorption, and thus, how quickly the fluid enters the circulation. The primary aim was to investigate the impact of varying amounts of a novel six-amino acid formula on water absorption and fluid balance markers, using gastrointestinal deuterium oxide kinetics. This study was a double-blind randomised controlled trial involving healthy participants. Each participant ingested one of three beverages (550–600 mL) in three separate studies. Results showed that the addition of a small amount of a novel amino acid formula (3.48 g/L) to a sugar-free rehydration beverage increased water delivery into the circulation compared to a 6% carbohydrate-containing rehydration beverage. However, the addition of greater amounts of amino acids (17.51 g/L) to a sugar-free rehydration beverage delayed fluid delivery, potentially due to delayed gastric emptying and/or intestinal transporter saturation. Authors concluded by suggesting that future research should assess a sugar-free rehydration beverage containing a small amount of a novel amino acid formula in scenarios where rapid delivery of water into the circulation is required (i.e. illness, heat stress or exercise), and also in participants with age-related differences in fluid retention.
PURPOSE
Rapid gastric emptying and intestinal absorption of beverages is essential for rapid rehydration, and certain amino acids (AA) may augment fluid delivery. Three sugar-free beverages, containing differing AA concentrations (AA + PZ), were assessed for fluid absorption kinetics against commercial sugar-free (PZ, GZ) and carbohydrate-containing (GTQ) beverages.
METHODS
Healthy individuals (n = 15-17 per study) completed three randomised trials. Three beverages (550-600 mL) were ingested in each study (Study 1: AA + PZ [17.51 g/L AA], PZ, GZ; Study 2: AA + PZ [6.96 g/L AA], PZ, GZ; Study 3: AA + PZ [3.48 g/L AA], PZ, GTQ), containing 3.000 g deuterium oxide (DO). Blood samples were collected pre-, 2-min, 5-min, and every 5-min until 60-min post-ingestion to quantify maximal DO enrichment (Cmax), time Cmax occurred (Tmax) and area under the curve (AUC).
RESULTS
Study 1: AUC (AA + PZ: 15,184 ± 3532 δ‰ vs. VSMOW; PZ: 17,328 ± 3153 δ‰ vs. VSMOW; GZ: 17,749 ± 4204 δ‰ vs. VSMOW; P ≤ 0.006) and Tmax (P ≤ 0.005) were lower for AA + PZ vs. PZ/GZ. Study 2: DO enrichment characteristics were not different amongst beverages (P ≥ 0.338). Study 3: Cmax (AA + PZ: 440 ± 94 δ‰ vs. VSMOW; PZ: 429 ± 83 δ‰ vs. VSMOW; GTQ: 398 ± 81 δ‰ vs. VSMOW) was greater (P = 0.046) for AA + PZ than GTQ, with no other differences (P ≥ 0.106).
CONCLUSION
The addition of small amounts of AA (3.48 g/L) to a sugar-free beverage increased fluid delivery to the circulation compared to a carbohydrate-based beverage, but greater amounts (17.51 g/L) delayed delivery.
© 2024. The Author(s).
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