Yogurt contains probiotics, a kind of “good” gut bacteria that may have health benefits. Researchers wanted to test out the relationship between probiotics and brain function, so they took three groups of 12 women each and fed one of the groups (the lucky group) yogurt with probiotics, one group a yogurt-like dairy product, and one group nothing. The idea was to show that what happens in humans’ guts directly affects their brains.
During the study, the yogurt group got the probiotic goodness twice a day, every day for four weeks. Before and after that four-week session, all 36 women in the study got fMRI scans. In both fMRI sessions, the women had their brains scanned at rest and during “emotion-recognition task”: in this case, they were shown frightened or angry faces and told to match the emotions to other frightened or angry faces. (Which sounds stressful. Perhaps yogurt could help.) Tasks like that are a measurement of activity in certain brain regions, and similar links have been found between gut changes and emotion recognition in animals, so this was a test to see if the process extended to humans.
Turns out it did, but not necessarily in the positive way you’d anticipate with a healthy food like yogurt: during the task, the women who ate the real yogurt actually had decreased activity in the part of the brain that regulates body sensations. But, in the resting brain scan, the women also showed increased connectivity in the periaqueductal gray region and the pre-frontal cortex, which affects cognition.
So what’s yogurt doing to your brain?
Hard to say. It’s a small sample size, and the data doesn’t seem to lead to a concrete conclusion about how the bacteria will affect thinking. But the researchers say this was more of a study to see if some kind of relationship existed between the bacteria and thought, which they say they did find. It’s more of an open question, now, how that relationship affects how much yogurt you’ll want to stock up on.