Oral rehydration solutions (ORS) have been in use since decades to prevent and treat dehydration associated with diarrhea. In the 1970s, the World Health Organization (WHO) recommended an ORS formulation with total osmolarity of 311 mmol/l for prevention and treatment of diarrheal dehydration.¹ This solution; however, caused gastrointestinal upset, nausea, and was associated with concerns about hypernatremia.² Later, the WHO revised the recommended formulation to an ORS with a reduced electrolyte content and osmolality of 245 mmol/l.^1,2

Lowering the sodium and glucose concentration in ORS led to significant reduction in stool output, vomiting and the need for intravenous therapy.³

However, the strong salty taste of the ORS sometimes becomes the reason of dehydrated children refusing to drink the solution. As a result, parents and health workers tend to flavor the ORS with some juice in order to improve its palatability. Flavoring can alter the electrolyte content and osmolality of ORS, and decrease its overall efficacy.

A study was conducted by te Loo and colleagues to determine the impact of flavoring ORS on electrolyte content and osmolality and the palatability of various solutions was compared with commercially flavored ORS.³

Five commercially available ORS were used in the study; of these only one was flavored. Investigators assessed osmolality, as well as sodium, potassium, chloride and glucose content after flavoring the ORS with different concentrations of apple juice, orange juice or orangeade. Two of the solutions were offered to 30 children and adults to evaluate their palatability.

All additions to ORS - apple juice, orange juice or orangeade -reduced sodium (-30 to -53 mmol/L) and chloride (-27 to -47 mmol/L) content. Potassium concentration was shown to increase (3 to 13 mmol/L) except for the ORS flavored with orangeade (reduction, 27.0 to 22 mmol/L).Osmolality appeared to increase to greater than 311 mOsm/kg. None of the solutions fulfilled the WHO criteria for ORS.Rehydration will therefore be less effective. Majority of study participants preferred the commercially flavored ORS and judged it as most palatable.

The authors thus advised against flavoring ORS, as it led to severe alterations of electrolyte concentration and osmolality and even palatability did not improve, in comparison with the commercially flavored ORS.

It is possible to add only small quantities of apple juice or orange juice to the ORS without changing the electrolyte composition and osmolality to a significant extent. Palatability does not appear to improve though, compared to commercially flavored ORS. Commercially flavored ORS should therefore be used with a composition thatfulfilsthe recommended criteria.

References

1. Munos MK, Walker CLF, Black RE. The effect of oral rehydration solution and recommended home fluids on diarrhoea mortality. Int J Epidemiol. 2010 Apr; 39(Suppl 1): i75–i87.
2. Sollanek KJ, Kenefick RW, Cheuvront SN. Osmolality of Commercially Available Oral Rehydration Solutions: Impact of Brand, Storage Time, and Temperature. Nutrients. 2019 Jul; 11(7): 1485.
3. te Loo DM, van der Graaf F, Ten WTA. The effect of flavoring oral rehydration solution on its composition and palatability. J Pediatr Gastroenterol Nutr. 2004 Nov;39(5):545-8.