WASHINGTON, April 16 (UPI) -- When the body and mind are stressed or anxious, the endocrine system is supposed to up its production of the hormone cortisol, a substance shown to play important an important role in healing, immune and metabolic process.
But new research suggests the body's ability to produce cortisol in response to stress is diminished by the consumption of sugar-sweetened drinks. Researchers at University of California, Davis, and the USDA Research Service found that sodas and juices sweetened with sugar suppresses both cortisol and stress-reduction processes in the brain.
Diet soda sweetened with the sugar substitute aspartame, however, was not found to have the same effects.
"This is the first evidence that high sugar -- but not aspartame -- consumption may relieve stress in humans," study author Kevin D. Laugero said in a press release. "The concern is psychological or emotional stress could trigger the habitual overconsumption of sugar and amplify sugar's detrimental health effects, including obesity."
Researchers arrived at their results after subjecting 19 women, ages 18 to 40, to specific diets and stress tests. For 12 days, 11 of the women drank one sugar-sweetened beverage at breakfast, lunch and dinner. The other eight women drank aspartame-sweetened beverages. Both groups were instructed not drink any other sweetened beverages.
Before and after the 12-day period, participants adhered to a low-sugar diet. They also took math tests. MRI imaging showed those how had been regularly drinking sugar-sweetened drinks, were less able to respond to the performance stress brought on by the math test.
"The results suggest differences in dietary habits may explain why some people under-react to stressful situations and others overreact," Laugero said. "Although it may be tempting to suppress feelings of stress, a normal reaction to stress is important to good health. Research has linked over- and under-reactivity in neural and endocrine stress systems to poor mental and physical health."
The new research was published this week in the journal Journal of Clinical Endocrinology & Metabolism.