Caffeinated soft drinks that are high in fructose are hugely popular worldwide. They need no introduction.
Researchers from the University at Buffalo in New York recently assessed soft drinks’ impact on kidney health when consumed during and after physical exertion.
Their findings have been published in the American Journal of Physiology—Regulatory, Integrative and Comparative Physiology.
Exercise, kidneys, and heat
When we exercise in a hot environment, blood flow through the kidneys is reduced. This helps regulate blood pressure and conserve water. It is a normal response and causes no harm.
However, in clinical settings, a steep drop in blood flow through the kidneys can cause acute kidney injury (AKI) because of the accompanying drop in oxygen supply to the tissues.
Earlier studies have shown that exercise, in general, but particularly in higher temperatures, increases biomarkers of AKI. At the same time, research also indicates that consuming a high-fructose soft drink increases AKI risk in rats experiencing dehydration.
After an intense workout, it is fairly common for people to drink soft drinks. Similarly, people who carry out manual labor in hot environments often indulge. It is important to understand whether this behavior can have negative consequences for kidney health.
To investigate, the researchers recruited 12 healthy, physically fit adults with an average age of 24.
Participants completed 30 minutes on the treadmill, then a further 15 minutes doing three tasks designed to mimic physical work on an agricultural site.
After this 45-minute surge of activity, the participants relaxed for 15 minutes. The research team provided each participant with either 16 ounces of a popular citrus-flavored, high-fructose, caffeinated soft drink or water. They repeated this 1-hour cycle a total of four times.
At least 1 week later, the participants returned and performed the 4-hour routine once again. This time, those that had the soft drink in the first trial received water and vice versa.