Zachary J. Schlader
The consumption of high fructose, caffeinated beverages during and following exercise in hot temperatures may both reduce renal function and elevate biomarkers of AKI, according to a study published in the American Journal of Physiology--Regulatory, Integrative and Comparative Physiology.
“These data indicate that drinking a soft drink during or following exercise in the heat does not hydrate,” Zachary J. Schlader, PhD, FACSM, assistant professor at the Center for Research and Education in Special Environments, department of exercise and nutrition sciences, at the University of Buffalo, told Healio Nephrology. “Also, the soft drink elevates in markers indicative of acute kidney injury. Collectively, our study supports recent animal work that suggests drinking soft drinks during or following exercise in the heat may be bad for kidney health. Emerging evidence [also] demonstrates associations between fructose consumption and the development of chronic diseases (including chronic kidney disease).”
After obtaining pre-exercise measurements of core temperature, heart rate, blood pressure, hemoglobin and hematocrit, researchers provided 12 participants (mean age, 24 years; 3 women) with either two liters of a soft drink or water during and following 4 hours of exercise in a 35 degree C, 5% relative humidity environmental chamber, meant to simulate a typical outdoor work thermal environment. Participants engaged in four 1-hour work-rest cycles of 45 minutes of exercise followed by 15 minutes of seated rest.
Data were collected pre- and post-exercise and at 24-hours.
The consumption of high fructose, caffeinated beverages during and following exercise in hot temperatures may both reduce renal function and elevate biomarkers of AKI.
Source: Adobe Stock
Researchers found that, post-exercise, 75% of participants who consumed the soft drink had stage 1 AKI, or increased serum creatinine at least 0.3 mg/dL or greater, vs. 8% of those who consumed water (P = .02).
Further, participants who consumed the soft drink had higher urinary neutrophil gelatinase-associated lipocalin during an overnight collection period compared with participants who consumed water (6 ng/dL vs. 5 ng/dL; P < .04).
Researchers also found that changes in serum uric acid were greater in those who consumed the soft drinks at post-exercise (P < .01) and at 24-hours (P = .05) than those who consumed water.
Finally, compared with those who drank water, greater increases of serum copeptin (P < .02) and greater reductions in eGFR (P < .01) were observed for soft drink consumers from pre- to post-exercise.
Further research is needed in this area, according to Schlader.
“We do not know what in the soft drink could have led to this response,” he said. “We also do not know the mechanisms by which soft drink consumption may elicit injury during exercise in the heat. Finally, we do not know the long-term effects of chronic soft drink consumption during exercise in the heat and its relation to the risk of kidney injury. This latter point could modify occupational practices.” – by Melissa J. Webb
Disclosures: The authors report no relevant financial disclosures.