Soft drinks worsen dehydration and kidney damage

Dehydration has been shown to result in chronic kidney injury, point out a team of scientists who had a theory that hydration with sugary beverages could damage your kidneys even more than dehydration alone over time.  

The research group involved in the study are from Central America, where a major epidemic of chronic kidney disease is occurring among workers in the sugarcane fields. “To date there have been reported to be over 20,000 deaths. While the aetiology is unknown, most studies suggest that recurrent dehydration is a major risk factor.”

Their theory is based on the notion that dehydration induced chronic kidney injury is likely due to activation of the aldose reductase-fructokinase pathway. This pathway is activated by dehydration itself, but can also be activated by simple sugars such as fructose and glucose in sugary drinks and thus could be made worse if hydrating with soft drink. 

To test the theory, they induced dehydration in rats and let them rehydrate with either plain water, a 11% fructose-glucose solution (same composition as typical soft drinks), or water sweetened with non-caloric stevia [1]. 

After 4 weeks they found that water repletion resulted in mild injury and oxidative stress in the kidneys, but rehydration with “soft-drink” resulted in greater dehydration and worse renal injury, despite larger total fluid intake. 

Rehydration with stevia water had opposite effects, maintaining hydration and preventing kidney damage. 

Dehydration was also associated with increased urinary sodium excretion or loss of salt, and this was worsened by rehydration with sugary water.

"An important message of this study is that the first fluid you drink to rehydrate following a period of dehydration should be plain water not a sugar laden drink," commented an accompanying editorial [2]. 

1. Garcia-Arroyo FE, et sl. Rehydration with Soft Drink-like Beverages Exacerbates Dehydration and Worsens Dehydration-associated Renal Injury. Am J Physiol Regul Integr Comp Physiol. 2016 Apr 6:ajpregu.00354.2015.  
2. Denton KM. You Are What You Drink! Editorial Commentary: Rehydration with Soft Drink-like Beverages Exacerbates Dehydration and Worsens Dehydration-associated Renal Injury. Am J Physiol Regul Integr Comp Physiol. 2016 Jun 8:ajpregu.00222.2016. doi: 10.1152/ajpregu.00222.2016. [Epub ahead of print]