Probiotics are the latest buzzword in nutrition.

They may also someday treat depression.

By now I’m sure you have heard and seen the term probiotic countless times in commercials and advertisements.

Yogurt, dietary supplement, natural food product, and even cosmetic companies are all promoting probiotic-containing products.

What are probiotics, and why are they important?

Probiotics are live bacteria that help maintain a healthy digestive system. Development of products which contain live bacteria is booming, due to the growing interest in the ingestion of ‘natural foods’ that might promote health

Over the past few years, studies have been even carried out to look at possible impacts of probiotics on behavior. This is where the concept of Psychobiotics started.

What are Psychobiotics?

A psychobiotic is

“a live organism that, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness,"

according to the authors of a new article in Biological Psychiatry.

In the article, evidence is reviewed that these bacteria, when ingested in adequate amounts, offer huge potential for the treatment of depression and other stress-related disorders.

The gut microbiota, which contains approximately 1 kg of bacteria, can be modified by diet and many other factors.

Your internal bio-organism population is not static and can change from day to day, starting at birth. Evidence has shown that even the form of birth delivery alters an individual’s microbiota.

Maternal Separation and Depression

Early life stresses, like maternal separation, are known to bring on long-term changes in the microbiome.

Study author Timothy Dinan and his team looked at one study that assessed the potential benefits of a specific probiotic, B. infantis, in rats displaying depressive behavior due to maternal separation.

The probiotic treatment normalized both their behavior and their previously-abnormal immune response. This study and others like it strongly support the hypothesis that probiotics have the potential to exert behavioral and immunological effects.

Some psychobiotics have been shown to have anti-inflammatory effects. This is important because depression and stress are both associated with inflammation in the body.

Infectious Diseases and Depression

Infectious diseases, such as syphilis and Lyme disease, can also produce depressive states. Evidence suggests that immune activations, perhaps via psychobiotic action, could alleviate such states.

According to the authors, “the intestinal microbial balance may alter the regulation of inflammatory responses and in so doing, may be involved in the modulation of mood and behavior.”

Human studies are still mostly non-existant, but a few have shown promising results.

In one human study, healthy volunteers received either a probiotic combination or placebo for 30 days. Those who received the probiotics reported lower stress levels. In a separate study, volunteers who consumed a yogurt containing probiotics reported improved mood.

“What is clear at this point is that, of the large number of putative probiotics, only a small percentage have an impact on behaviour and may qualify as psychobiotics,” said Dinan.

“This intriguing new area of research may open new possibilities for the treatment of depression,” said Biological Psychiatry Editor Dr. John Krystal .

Original Study

Timothy G. Dinan, Catherine Stanton, John F. Cryan. Psychobiotics: A Novel Class of Psychotropic. Biological Psychiatry, 2013; 74 (10): 720 DOI:10.1016/j.biopsych.2013.05.001

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