Effect of beverage glucose and sodium content on fluid delivery

Rapid fluid delivery from ingested beverages is the goal of oral rehydration solutions (ORS) and sports drinks.

The aim of the present study was to investigate the effects of increasing carbohydrate and sodium content upon fluid delivery using a deuterium oxide (D2O) tracer.

Twenty healthy male subjects were divided into two groups of 10, the first group was a carbohydrate group (CHO) and the second a sodium group (Na). The CHO group ingested four different drinks with a stepped increase of 3% glucose from 0% to 9% while sodium concentration was 20 mmol/L. The Na group ingested four drinks with a stepped increase of 20 mmol/L from 0 mmol/L to 60 mmol/l while glucose concentration was 6%. All beverages contained 3 g of D2O. Subjects remained seated for two hours after ingestion of the experimental beverage, with blood taken every 5 min in the first hour and every 10 min in the second hour.

Including 3% glucose in the beverage led to a significantly greater AUC 60 min (19640 ± 1252 δ per thousand vs. VSMOW.60 min) than all trials. No carbohydrate (18381 ± 1198 δ per thousand vs. VSMOW.60 min) had a greater AUC 60 min than a 6% (16088 ± 1359 δ per thousand vs. VSMOW.60 min) and 9% beverage (13134 ± 1115 δ per thousand vs. VSMOW.60 min); the 6% beverage had a significantly greater AUC 60 min than the 9% beverage. There was no difference in fluid delivery between the different sodium beverages.

In conclusion the present study showed that when carbohydrate concentration in an ingested beverage was increased above 6% fluid delivery was compromised. However, increasing the amount of sodium (0-60 mmol/L) in a 6% glucose beverage did not lead to increases in fluid delivery.