Oxytocin Creates Link Between Stress and Digestive Issues, New Research Suggests

Oxytocin, a hormone related to feelings of love and bonding, may play a major role in regulating gastrointestinal functions, especially as it pertains to stress, according to the preview of a new study to be published in The Journal of Physiology.

Looking at rats in a controlled laboratory setting, researchers introduced stress through several scenarios, such as by restraining them or forcing them to swim in a container where they couldn't touch the bottom. They then tested the rats' gastric emptying rate—how quickly food leaves the stomach—of a solid meal, along with assessing their hormone levels.

Thirty minutes before the stress tests, researchers injected the rats with a saline solution (control) or a drug designed to trigger the release of oxytocin. They found that oxytocin had a significant effect on gastric emptying. The rats that had been under the most stress had the slowest emptying rate, but when oxytocin was triggered, it increased muscle contractions in the stomach and shortened the delay.

While the results of the study only provide preliminary evidence, they do hold promise for further investigation. The information could lead to new targets for digestive drug development in the future, especially since oxytocin hasn't been investigated as a stress-response hormone in the past.

Reevaluating the Role of Oxytocin

In terms of stress response and gut health, oxytocin has not been thought to be a major player compared to other hormones like cortisol, dopamine, and serotonin.

Serotonin in particular has garnered the most attention. Since it's so strongly connected to mental health, it's often a target in antidepressant medications. About 90% of serotonin is produced in the digestive tract, which then sends signals up to the brain, according to Elaine Hsiao, PhD, research assistant professor of biology and biological engineering at Caltech.

Oxytocin, sometimes called the "love hormone" or the "cuddle hormone" because it's released when people bond socially or physically touch each other, is often highlighted not for its potential role in gut health, but for the birth process. The hormone causes uterine contractions, helps shrink the uterus after delivery, aids in breastfeeding, and promotes mother-child bonding.

A 2007 study in Psychological Science concluded that the higher a woman's oxytocin levels in the first trimester of pregnancy, the more likely she would be to initiate bonding behaviors with a baby, such as singing to the infant.

Gut and Brain Health

Highlighting oxytocin's potential role in digestive health adds to evidence about the importance of the gut-brain axis, says Lisa Mosconi, PhD, author of Brain Food: The Surprising Science of Eating for Cognitive Power.

"The value of maintaining good gut health for better emotional regulation can't be overstated, because they're so connected," she says, adding that if one is thrown off, the other can be affected, sometimes dramatically. "It's a delicate balance because they're sending messages to each other all the time. But that's also the good news because if you work to improve one, you'll likely see benefits for the other."

That means taking steps for better brain health—like eating healthy foods and pursuing de-stress strategies—can also be beneficial for your digestion.

Get Moving

Focusing on foods like fruits, vegetables, whole grains, and lean proteins can be useful for better hormone regulation, but another solid strategy is simply to move more. Potentially a lot more.

“Your brain is wired to respond positively to exercise,” says Loretta Graziano Breuning, PhD, author of Habits of a Happy Brain. “When you exercise consistently, your brain gets even more efficient at making and releasing the natural chemicals that keep you upbeat, like serotonin, dopamine, and oxytocin.”

Although the recent study focused on oxytocin specifically, hormones like these don't work independently, says Breuning. Rather, they are released in combinations that are thought to improve functioning—creating streamlined processes related to everything from blood sugar control to stress relief to digestion.

Exercise can provide a major boost. Other strategies that could help with oxytocin include:

• Hugging (it is called the cuddle hormone, after all)
• Petting an animal
• Getting or giving a massage
• Having sex
• Meditating
• Using visualization and deep breathing

As you tap into your feel-good hormones, it's likely your digestive system will feel good too.