How Probiotic Yogurt May Affect Mental Health

March 10th 2017

Kyle Jaeger

Probiotic yogurts are marketed as products that can promote digestive health and support your immune system. But as Science Daily notes, a new study published in the journal Scientific Reports suggests that there could be another benefit to eating yogurt: it might relieve symptoms of depression. 

Researchers at the University of Virginia School of Medicine claim to have reversed symptoms of depression in lab mice by feeding them the bacteria, Lactobacillus, which is found in probiotic yogurts. They further claim to have discovered how the bacteria affects mood — by inhibiting the production of a metabolite linked to depression.

"The big hope for this kind of research is that we won’t need to bother with complex drugs and side effects when we can just play with the microbiome," lead researcher Alban Gaultier said to Science Daily in a press release Tuesday. "It would be magical just to change your diet, to change the bacteria you take, and fix your health — and your mood."

How the experiment was conducted.


In order to explore the relationship between gut bacteria and mood, the researchers subjected the mice to a series of stressful stimuli, such as: strobe lights, swim tests, cage tilting, and wet bedding. They compared the contents of their guts before and after the stress tests and determined that the presence of Lactobacillus was significantly depleted after the mice experienced stress.

In other words, stress reduces the amount of Lactobacillus that is naturally present in the gut.

"This is the most consistent change we’ve seen across different experiments and different settings," Ioana Marin, the study's co-author, said in the press release. "We see Lactobacillus levels correlate directly with the behavior of these mice."

Then came the next test. What happened when the stressed-out mice, which exhibited "depressive-like behavior," were fed Lactobacillus?


The probiotic bacteria supplement that were fed to the mice appeared to normalize their behavior. "A single strain of Lactobacillus is able to influence mood," Gaultier said in the press release.

To support their findings, the researchers then set out to identify the biochemical mechanism that potentially links gut bacteria and behavior. They found that the more Lactobacillus a mouse had in their gut, the less kynurenine — a metabolite found in the bloodstream — they produced. Previous studies have determined that kynurenine is associated with depression.

The results are promising and the researchers intend to follow up with human studies, but they also cautioned that people suffering from depression should continue to adhere to their treatment regimen. There's no harm in eating yogurt, of course, but further research is needed to cement the link between the probiotic bacteria and mental health.