Reprinted with permission from World At Large, a news website of nature, politics, science, health, and travel.

Probiotics have already been identified in published studies as providing an ability to help alleviate allergy symptoms. Now, the same can confidently be said of regulating mental health.

Some of the most extensive research into the human microbiome has revealed that the diversity of certain bacterial species in your gut can help, sometimes significantly, with many of the most commonly diagnosed mental disorders such as depression, anxiety, or PTSD.

This includes work from the American Gut Project, which sources the world's largest collection of gut microbe samples—more than 11,000—for use in scientific research. The project findings, while purely observational, suggest that bacterial diversity and richness in the human gut has the capacity to improve a variety of depressive symptoms.

In this paper that was recently published in the journal Nutrition, Iranian scientists found that markers for depression were reduced when taking a probiotic supplement containing particular microbes called lactobacillus casei and lactobacillus acidophilus.

In this small randomized, double-blind, placebo controlled trial, 40 people with major depressive disorder were given an 8-week course of probiotics. Diet and exercise activity were reported and controlled for, and after the 8 weeks ended, self-administered questionnaires revealed that the patients who had received a probiotic supplement had significantly lower scores on a Depression Inventory than those who had received placebo.

The results were similar to an earlier study showing probiotics alleviating anxiety.

Blood tests also tended to show decreased insulin levels and insulin resistance, increased glutathione levels, and lower inflammation markers of C-reactive protein concentration in the probiotic group.

C-reactive proteins are compounds produced in the liver in response to inflammation. High levels can indicate anything from a simple bacterial infection to cancer. This is typical of inflammatory molecules in our bodies, as several have been linked with almost every known disease—including depression and anxiety—and low levels of inflammation have been suggested as a potential corollary of longevity in humans.

For years, people have been eating cheese as a digestive assistant after meals, particularly in Europe where cheese holds a more prominent place in local culture and eating habits. Europe also has far less restrictive laws for the manufacturing and distribution of raw milk products.

L. casei and L. acidophilus, which can be found in supplements, are also common microbes found in raw or unpasteurized cheeses and yogurts, or in pasteurized dairy products which have been cultured. In fact, researchers have hypothesized that cheese can be an easier, less-expensive, and effective way of offering probiotic supplements to the public, since many cheesemakers use L. acidophilus and L. casei as lactic-acid starters in cheese production.

In one of the two most thorough reviews of probiotic–depression literature, Roumen Milev and Caroline Wallace found that out of 7 studies that sought to establish whether probiotics can help alleviate MDD, anxiety, and improve cognition and mood, all but 2 found that it did. Across all 10 studies analyzed, the most common probiotic strain used was L. casei.

The study acknowledged that the increased expressions of C-reactive proteins, as well as pro-inflammatory cytokines (like TNF-A, IL-1B, and IL-6), are recurring motifs in patients with symptoms of a mental or anxiety disorder, and suggested this might be due to increased gut-permeability, also known as "Leaky gut syndrome".

It is hypothesized that probiotic food and supplements improve the stomach and gut lining, reducing permeability and therefore inflammation, just as was found in the Iranian paper.

All this perhaps suggests that yogurts and cheese—especially if cultured, like kefir—can play a healthy role in the modern diet.

Help To Heal Your Friends' Negativity By Sharing The Intriguing Research To Social Media…