New Danish research suggests that supplementing an unbalanced diet with probiotics may help protect against diet-related depression.
For the study, researchers at Aarhus University in Denmark observed rats who were fed an extra fatty and fiberless compound feed. Some of these rats simultaneously received a mix of microorganisms, mostly in the form of lactic acid bacteria, in their drinking water.
They found that the rats that lived solely on the fatty diet developed depressive behaviors, but the rats receiving the probiotics-enriched drinking water remained neutral in their behavior. In other words, the probiotics helped offset the consequences of the unhealthy diet, said Anders Abildgaard, M.D., Ph.D., who conducted the study as part of his doctoral dissertation.
The findings appear in the journal Brain, Behavior, and Immunity.
In particular, the rats that did not receive probiotics were found to have an increased number of white blood cells in their brain tissues, which can be a sign of chronic inflammation. Increased white blood cells are also seen in the fatty tissues and liver of people who are overweight and in diabetics. In contrast, the white blood cells were normal in the brains of the rats with probiotics in their drinking water.
“This may indicate that one of the things the probiotics do is work to reprogramme the immune system,” said Abildgaard. “Specifically in this study, the rats offset the consequences of the fatty diet with the help of probiotics, so that they were on a par with their peers in the control group.”
“This is a fascinating discovery which supports the conclusion that probiotics, which normally do good in the intestines, also affect the brain. That makes the result interesting for the treatment of depression.”
For the study, the rats were divided into four groups. Two groups of rats were fed an extra fatty and fiberless diet, while one of these also drank water with probiotics. Two control groups were simultaneously fed a healthier diet with more fiber and half as much fat.
After 12 weeks, the researchers could observe that the rats on the fatty compound feed without probiotics behaved more depressively during a swimming test.
“Rats cannot suffer a depression in a clinical sense like people can, but they become passive and unable to cope with stressful situations. We interpret this as depressive-like behaviour,” said Abildgaard, who noted that the study supports familiar knowledge about how an unhealthy diet gives an unhealthy state of health, both physically and mentally.
While it is difficult to say whether the results are applicable to people with depression, since animals obviously do not behave like humans, Abildgaard said it is possible that some people who suffer from depression can benefit from probiotics.
“There is an increasing amount of research which suggests that an unhealthy diet contributes towards triggering or maintaining a depression. We also know that patients suffering from depression generally live in a more unhealthy way compared to the average, probably because they do not have the necessary resources to lead a healthy lifestyle,” he said.
“Though probiotics do not make food healthier and do not affect weight or blood sugar levels in the laboratory animals, probiotics can nevertheless help to lessen the depressive symptoms and give patients the resources to change their lifestyle, so the vicious circle is broken.”
Source: Aarhus University