Sugary beverages appeared to suppress cortisol and stress responses in the brain, but diet drinks sweetened with aspartame did not produce the same effect, according to data published in the Journal of Clinical Endocrinology & Metabolism.
“This is the first evidence that high sugar — but not aspartame — consumption may relieve stress in humans,” study researcher Kevin D. Laugero, PhD, of the University of California, Davis, and the U.S. Department of Agriculture’s Agricultural Research Service, 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.”
Approximately 40% of people report eating more in response to stress, but an estimated 80% report eating more sweets per calorie regardless of stress, according to background information in the study. However, while eating to relieve stress is widely appreciated, the actual physiological grounds for the behavior have yet to be identified.
“Rodent studies suggest that sugar consumption may activate a glucocorticoid-metabolic-brain-negative feedback pathway, which may turn off the stress response and thereby reinforce habitual sugar overconsumption,” the researchers wrote.
To further investigate this association, Laugero and colleagues conducted a parallel-arm, double-masked diet intervention study in 19 women aged 18 to 40 years with BMIs ranging from 20 to 34.
They randomly assigned eight women to consume beverages sweetened with aspartame and 11 to drink sugar-sweetened beverages. Over 12 days, the women drank one of the assigned beverages at breakfast, lunch and dinner and were asked not to drink other sugar-sweetened beverages, including fruit juice.
For 3.5 days prior to and after the study, participants consumed a standardized low-sugar diet and resided at the UC Davis Clinical and Translational Science Center’s Clinical Research Center.
The researchers evaluated regional brain responses to a Montreal Imaging Stress Task — in this case, a math test — using functional MRI and measured cortisol levels using saliva samples.
Results showed that women in the sugar-sweetened beverage group experienced diminished cortisol response to the math test, as compared with those in the aspartame-sweetened beverage group (P=.024).
Drinking sugary beverages was also linked to a lower reactivity to naltrexone (P=.041), lower nausea and a trend toward lower cortisol (P=.080), the researchers reported.
Additionally, women who drank sugar-sweetened beverages demonstrated greater activity in the left hippocampus than those who drank beverages sweetened with aspartame (P=.001). The hippocampus, which is a part of the brain that is involved in memory and is sensitive to stress, is generally less active when the body is under stress.
Laugero noted that these data shed light on why people may be attracted to “comfort food” when stressed.
“The results suggest differences in dietary habits may explain why some people underreact to stressful situations and others overreact,” he 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.”