Soft Drink Consumption During and Following Exercise in the Heat Elevates Biomarkers of Acute Kidney Injury

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ByCrossFitFebruary 19, 2019

This small clinical trial, published by Christopher L. Chapman et al. of the University of Buffalo, considers the impact of soft drink consumption (Mountain Dew) on kidney function during and after activity, specifically simulating the impact of soft drink consumption on physical labor in heat.

Soft drinks already have a bad name as they appear to have a major role in causing obesity, fatty liver and diabetes. However, soft drinks are also dehydrating and should not be used as a hydration drink in any shape or form. Indeed, what we are learning from this recent study is that soft drinks may actually inflict kidney injury in individuals who are dehydrated and have heat stress.

Subjects completed four one-hour exercise cycles, each 45 minutes on (treadmill-walking at 3 mph at a grade sufficient to achieve 55 percent of max heart rate, followed by lifting tasks) and 15 minutes off, in an environmental chamber set to 95 degrees Fahrenheit and 61 percent relative humidity. These parameters were chosen to simulate the environment of outdoor physical labor. Participants consumed a total of 2 liters in 500 mL doses of beverage over four hours, then an additional liter afterward.

There were no significant differences between groups in terms of heart rate or performance, nor significant differences in hydration levels. However, there were more consistent increases in serum creatinine in the soft drink group compared to controls, with 8/12 in the former group and 1/12 in the latter showing an increase of more than 0.30 mg/dL, which meets a criterion for acute kidney injury (1).

The authors concluded:

“The present study provides evidence … that consuming a soft drink during and following exercise in the heat reduces renal function and increases markers of AKI compared to when consuming water. Specifically, renal function was reduced to a greater extent in the Soft Drink trial, as demonstrated by larger increases in serum creatinine and reduced overnight urine flow rate compared to water. Furthermore, the incidence of stage 1 AKI and overnight urinary NGAL, a marker of renal tube injury, were both higher in the Soft Drink trial. Our data also indicate that elevations in vasopressin (i.e., copeptin) and serum uric acid may play important roles in the mechanisms that lead to the development of AKI evoked by consuming a soft drink during and following exercise in the heat compared to when consuming water.”

 

References

  1. Rahman M, Shad F, and Smith M. Acute Kidney Injury: A Guide to Diagnosis and Management. American Family Physician 86(7): 631-639, 2012.

Comments on Soft Drink Consumption During and Following Exercise in the Heat Elevates Biomarkers of Acute Kidney Injury

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Clarke Read
February 20th, 2019 at 3:35 am
Commented on: Soft Drink Consumption During and Following Exercise in the Heat Elevates Biomarkers of Acute Kidney Injury

Two points that are obvious to many of you but deserve emphasis:

1. While this trial looked specifically at subjects drinking Mountain Dew during moderate exertion in heat, many of the drinks most heavily marketed as rehydration formulas contain similar amounts of sugar;

2. The level of activity in this trial was moderate in intensity, but high in duration (with three out of four hours active). This is directly applicable to a variety of active professions, but this study doesn't directly tell us about the impact on shorter-duration, more intensive exercise. Just as importantly, we don't know if these signs of acute kidney injury cause chronic kidney damage over time.


Other papers have suggested a link between fructose or sugary beverage consumption and kidney damage:

https://www.sciencedirect.com/science/article/pii/S0272638615011567

https://www.physiology.org/doi/full/10.1152/ajprenal.00181.2007


But as far as I know, this remains an interesting, but preliminary, branch of research on the impact of sweetened beverages on health.

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Shakha Gillin
February 20th, 2019 at 6:40 am

Clarke, brilliant links.


Kidney damage has killed over 20,000 young sugar cane workers in Nicaragua and El Salvador.


Dr Johnson’s theory on Sugar Cane Kidney Disease involves metabolic pathways activated by dehydration, and lethal kidney damage caused by fructose from rehydration with sodas and fruit juices.


Sugar Cane Kidney Disease is the real life version of Chapman’s study. Workers are working hard, for long hours, dehydrated, and rehydrating with soda. This study by Chapman et al supports Johnson’s theory re fructose with quantifiable laboratory data.


Interesting, but sad.

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Matthieu Dubreucq
November 26th, 2019 at 8:00 pm

Thanks for the links!

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