Probiotics are not only good for the gut and immune system, but also are able to relieve depression. Indeed, various research has now confirmed that the composition of the intestinal bacteria affects the psyche. Therefore, probiotics can help relieve depression, a recent study confirms.

Probiotics and prebiotics

Probiotics alone, but also in combination with prebiotics, significantly alleviate the symptoms of depression. Many foods, such as kimchi, sauerkraut and even olives, are good sources of probiotics. Not to mention, of course, yoghurt and kefir. They are therefore recommended for depression.

What is the difference between prebiotics and probiotics?

Prebiotics are indigestible food components through which the beneficial intestinal bacteria multiply. Probiotics are preparations that contain living bacterial strains, such as lactic acid bacteria, bifidobacteria and yeasts.

What the new study shows is that pre- and probiotics actually have an effect on depression. They also relieve anxiety, but the effect on depression is stronger. The study results were published in the journal BMJ Nutrition, Prevention & Health.

The intestinal-brain axis

The main reason why probiotics relieve depression is the connection between the brain and the gut. The intestinal flora cooperates with the central nervous system and both are in constant communication with each other. The gut sends signals to the brain and get feedback so that both work well. This is why sedatives, for example, work not only on the brain, but also on the gut. And in this way, the gut bacteria also influence mental and psychological function.

Yoghurt alone is able to relieve the symptoms of depression

Yoghurt alone is able to brighten the mood of a depressed person. There is even evidence that yoghurt cancels out the depressive state thanks to its lactic acid bacteria. To gain an accurate understanding of the extent to which probiotics relieve symptoms of depression, the researchers examined studies from 2003 to 2019 inclusive. Participants were over 18 years of age, diagnosed with depression and/or anxiety, and they were given pre- or probiotics.

All the studies showed a significant improvement in depressive symptoms. For the studies, participants took capsules with one or more bacterial strains. The dose varied between two and 20 billion CFUs (colony forming unit). A serving of 100 grams of yoghurt usually contains 100 million microorganisms per gram, and thus contains about ten billion bacteria. With kimchi, it’s about the same. That’s enough to relieve depression. Twelve different strains of Firmicutes and Actinobacteria were studied. Lactobacilli and bifidobacteria were also among them. Of the twelve strains, 11 improved the symptoms of depression. Both alone and in combination with other bacteria.

The bacterium L. plantarum did not relieve the symptoms, but had a positive influence on the thinking performance. This type of bacteria can be found, for example, in kimchi.

Prebiotics alone had no significant effect on depression, but works well in combination with probiotics.

How do probiotics work?

Probiotics produce active substances such as nerve messengers (neurotransmitters). These useful inhabitants of the gut produce substances that relieve depression. These include GABA (gamma-amino butyric acid), which is produced in the brain from glutamate, as well as the messenger substances serotonin, catecholamine and acetylcholine. Through the intestinal wall cells, these messenger substances send signals to the brain and thus exert an effect. Special probiotics have their own very special effect. So it is not surprising that some probiotics relieve depression.

Againt stress and depression

  • By taking L. helveticus and B. longum for 30 days, stress, especially anger, and also fears are reduced.
  • The combination of L. rhamnosus and L. helviticus normalizes anxious behavior and improves learning and memory impairments.
  • B. longum and B. brevealso have a similarly good effect on the psyche.
  • L. plantarum is useful for increasing the production of dopamine and serotonin, which also reduces depressive behavior and lowers the concentration of the stress hormone cortisol.

Against Chronic exhaustion

L. casei Shirota relieved chronic fatigue symptoms in the studies. For this purpose, patients received CFU 24 billion for eight weeks. Exhaustion and existing fears subsided.

Because the effect of some probiotics on the psyche is strong, some probiotics have already been nicknamed “Psychobiotics”.

Bacteria as an antidepressant

It is an interesting fact that probiotics relieve depression and brighten the mood. Although these findings are not new, new facts have been discovered in recent years. But as early as the early 20th century, scientists discovered that people who ate fermented foods lived longer and healthier lives.

Interestingly, the effect goes further than just alleviating depression. There is also an effect on autism. When children receive Bacteroides fragilis early in their lives, it alters certain behavioral disorders associated with autism. The bacterium L. reuteri even eliminates the behavioral disorder in autism. The bacterium L. rhamnosus, which is found in many dairy products, also has a positive effect on social behavior and dampens obsessive-compulsive behaviour. It is therefore worth using probiotics as a supportive treatment for mental health problems.

Angie Mahecha

An fitness addict passionate of all things nature and animals, Angie often volunteers her time to NGOs and governmental organizations alike working with animals in general and endangered species in particular. She covers stories on wildlife and the environment for the Scientific Origin.