New research suggests consuming sugary drinks could suppress the hormone cortisol and stress response in the brain.

The researchers found drinks sweetened with aspartame did not have the same stress-relieving effect, the Endocrine Society reported.

"This is the first evidence that high sugar - but not aspartame - consumption may relieve stress in humans," said one of the study's authors, Kevin D. Laugero, of the University of California, Davis, and the U.S. Department of Agriculture's Agricultural Research Service. "The concern is psychological oremotional stress could trigger the habitual overconsumption of sugar and amplify sugar's detrimental health effects, including obesity."

To make their findings the researchers looked at 19 women between the ages of 18 and 40. Eight of the participants consumed aspartame-sweetened beverages, and 11 had beverages that were sweetened with sugar over a period of 12 days. The women consumed these drinks at breakfast, lunch and dinner and were instructed not to drink any other sugary beverages.

The women underwent functional MRI screening and performed math tests to demonstrate the brain's stress response. They also provided saliva samples to test cortisol levels, which is a hormone made by the adrenalin glands that is essential for the body's response to stress.

The findings showed women who drank sugar-sweetened beverages had a diminished cortisol response to the math test  and more activity in the hippocampus  than those who consumed the artificially sweetened beverages.

"The results suggest differences in dietary habits may explain why some people underreact 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 findings were published in a recent edition of the Journal of Clinical Endocrinology & Metabolism.