A new study suggests that there may be an effective alternative to medication for the treatment of depression: probiotic bacteria found in yogurt.
“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,” says lead researcher Alban Gaultier, Center for Brain Immunology and Glia at Virginia.
“It would be magical just to change your diet, to change the bacteria you take, and fix your health and your mood,” he adds.
First, the researchers analysed the gut microbiome of mice before and after they were exposed to stress. “When you’re stressed, you increase your chance of being depressed, and that’s been known for a long, long time,” notes Gaultier.
The team found that stress led to the loss of Lactobacillus in the rodents’ guts, and this led to the onset of depression-like symptoms.
Further investigation revealed that levels of Lactobacillus in the gut influence levels of a blood metabolite called kynurenine, which previous studies have associated with the development of depression.
In this study, when Lactobacillus levels in the mice were decreased, levels of kynurenine increased, and this led to the development of depression-like symptoms.
“This is the most consistent change we’ve seen across different experiments and different settings we call microbiome profiles,” says study co-author Ioana Marin, also of the Center for Brain Immunology and Glia.
Not only were the rodents’ Lactobacillus levels replenished as a result, but their depression-like symptoms were also reversed.
These findings indicate that including Lactobacillus in the diet has the potential to treat depression by increasing kynurenine levels, though the researchers caution that much more research is needed to confirm this theory.
“There has been some work in humans and quite a bit in animal models talking about how this metabolite, kynurenine, can influence behaviour,” notes Marin. “It’s something produced with inflammation that we know is connected with depression. But the question still remains: How? How does this molecule affect the brain? What are the processes? This is the road we want to take.”
In the meantime, the researchers say that there is no harm in patients with depression including yogurt in their diet. However, they stress that these individuals should not discontinue any medications without talking to their doctors.
