Almost everyone must have gulped down a probiotic drink at least once in his life. Probiotics, as defined by the World Health Organization (WHO) and the Food and Agriculture Organization (FAO), are “live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host.” These microorganisms usually come in the form of bacteria similar to those that normally thrive in the human gut. Because they deliver beneficial effects to their hosts, they are commonly referred to as “good bacteria.” To have a taste of these “good bacteria,” food manufacturers have developed different probiotic-containing products such as dietary supplements, soy beverages, yogurt, fermented and unfermented milk, and other functional drinks. Aside from their digestive benefits, probiotics can be consumed as complementary and alternative medicine (CAM).
In a recent study, researchers claim that consuming probiotic products can change the brain chemistry involved in stress and anxiety. Results revealed that the kind of foods that individuals eat can directly influence their emotions and affect how the brain and body react. They observed that this effect is associated with the action of the vagus nerve, a type of cranial nerve that branches out into the stomach, thereby connecting it to the brain. For example, if an individual eats a spoiled food, the vagus nerve helps to detect and transmit the sickening feeling and malaise. This happens because the vagus nerve plays a key role in generating signals from the gut and transmitting them to the brain.
In mice, the effects of the probiotic Lactobacillus rhamnosus JB-1 fed to one group were compared with the behaviours of those that were only given broth. Based on observations, the brain chemistry of mice fed with the probiotics exhibited lower stress level, as well as anxiety and depression-related behaviours in contrast to the other group of mice. The researchers concluded that ingesting the bacteria may have reduced the levels of the stress hormone corticosterone. It is also likely that the bacteria have altered the action of GABA, a brain chemical that acts directly on nerves to decrease their activity. This finding may have significant implications on the management of anxiety and depression-related disorders in humans.
Stress affects the gut physiology and may influence gastro-intestinal diseases. Usually, commensal microorganisms and their hosts demonstrate a symbiotic relationship. Yet, stress tends to decrease the number of Lactobacilli and increase the growth and mucosal uptake of pathogens, including E. coli and Pseudomonas. Furthermore, these intestinal microorganisms can sense if the host has become stressed. This provides the pathogenic bacteria with the opportunity to boost their virulence and eventually cause more damage to the host. The probiotics, then, counteract the stress-induced effects in the intestinal barrier, visceral sensitivity, and gut motility, which require strain specificity. In addition, direct bacterial-host cell interaction and soluble factors mediate these effects. These pathogens also compete for the essential nutrients and induce the release of epithelial heat-shock proteins. Thus, probiotic treatment may be administered to patients who experience stress-related intestinal disorders.
Since the food can directly affect how individuals feel, it is recommended that probiotics be taken. The “good bacteria” will not only aid in proper digestion and improve immune health but also reduce stress-related disorders.