Anyone who has ever had a stomach bug knows it can really subdue your spirits as well as your appetite. But other parts of the gut microbiome can have the opposite effect, and make you feel great. Irish researchers have found a type of gut bacteria that seems to have directly interacted with the brains of mice, reducing stress and depression.
Scientists fed mice a broth containing Lactobacillus rhamnosus, a strain of Lactobacillus species that is found in mouse gastrointestinal systems, and watched the mice's behavior. They appeared less stressed and depressed than mice who got a plain broth, the researchers reported. When they were placed in water to deliberately stress them out, the L. rhamnosus-fed mice also had lower levels of stress hormones.
John Cryan, a neuroscientist at University College Cork in Ireland, also monitored the animals' brains to watch for changes. He and colleagues found heightened activity in one of the receptors for a neurotransmitter called GABA, which regulates psychological processes. Certain depression drugs target GABA receptors, ScienceNow points out. Cryan and his colleagues found that certain portions of the neurotransmitter that are normally reduced during depression were more highly expressed in the L. rhamnosus mice. And other areas that are increased during depression were less pronounced in the L. rhamnosus mice.
To prove there really was a connection between the stomach bacteria and GABA activity, the researchers got new mice and cut the nerve that allows the gastrointestinal tract to communicate with the central nervous system. Then they fed these mice the broth, and the GABA receptors and mouse behavior remained at normal, pre-bacteria-enhanced levels.
This is not the first study to examine a connection between gut bacteria and psychological/brain physiological changes. Last summer, a British study found that the urine of autistic children has a distinct chemical signature associated with gut bacteria. Researchers at Imperial College London were not sure whether the bacteria were producing some kind of metabolic byproducts that could contribute to autism.
The Irish researchers say they still want to determine how the bacteria interact with the GABA receptors.
The chose L. rhamnosus because they happened to have it handy, and because related Lactobacillus species are so common in "probiotic" food supplements, ScienceNow reports. The bacteria is used to make foods like sourdough bread, yogurt and cheese. The paper was reported in the Proceedings of the National Academy of Sciences.
It's amazing when scientists find evidence for "folk wisdom" of olden days... in this case that diet affects mood...
Eating Chocolate has proved this long ago a direct connection to our moods... In fact, I am sure this is true of thousands of foods; just ask any good chef.
I'm not talking about the obvious observable behavior of someone eating a tasty meal and reporting feeling good about it.
I'm talking about the older beliefs that various foods affected your temperament. (e.g. eating spicy peppers results in lustful desires hours or days after the meal is done, eating corn flakes results in good morals [per Kellog], etc.)
This study shows strong evidence that the effects of what you eat go beyond just the flavor you experience in your mouth.
@B.V. Yes food does alter our moods. It's amazing, you and I agree.
I don't know if any of the previous people who commented actually read the article. But to clarify, the article is not talking about food affecting mood, it's talking about the presence of a specific bacterium(L. rhamnosus) in the intestines affecting mood.
Yes, I did read the article.
I was implying that when people eat food that they also eat bacteria, and that the mood-altering effects of various dietary choices observed hundreds of years ago seem more plausible when viewed in light of this study. (In contrast to previous explanations that the taste of food itself is what was primarily responsible for the moods of people).
@MaxwellMudd, Sir, I did read the article too, but I went off on a tangent...... I do that. ;)