The classic definition of probiotics is “live microorganisms that may confer a health benefit on the host”. A more useful description is that probiotics are generally bacteria or yeasts that help you remain healthy. After growing up in an environment that encourages the use of anti-bacterial soap, sanitary hand gel and prescription antibiotics, this may seem confusing. How can it be that something that is known for years to make people ill, actually also keep people healthy? What are probiotics and how do they work? Read further to find out.
Early evidence of probiotics
The first published report that microorganism were involved in human health was in 1907 by Elie Metchnikoff. Dr. Metchnikoff noticed that there appeared to be a correlation between the ingestion of lactic acid-producing bacteria in yoghurt and longevity in certain populations. A more colorful early story about the effectiveness of probiotics is the discovery of Bacillus subtilis by the Nazi’s. Seeking to find a cure for dysentery, they discovered that local Arabs ingested fresh camel dung to ward off the disease. Analysis of the dung revealed that B. subtilis was the protective agent.
Microorganisms are everywhere
Ingesting fresh camel dung is not what most of us would consider a healthy habit. However, most of us do eat yogurt, kefir, cheese, sauerkraut, and other fermented foods, which are full of bacteria and yeast.
To bring this in perspective, it’s important to realize that our environment is anything but sterile. It’s teeming with bacteria and this is also true for the body. Research has found that both the outsides and insides of our bodies are breeding grounds for bacteria and other microorganisms like yeast. This makes sense. We’re warm and are continually providing nourishment in the form of dead skin and ingested food. The colon, the most bacteria rich area in the body, is known to harbor trillions of bacteria. In fact, microorganisms makes up to 60% of dry fecal mass and around 1000–1150 different species inhabit our bodies. This set of species is termed the “microbiota”. General terms for the microorganisms in the gut are “intestinal flora” or “commensal bacteria”.
Bacteria turned bad
In general, our commensal bacteria are harmless. However, there are situations when this is not the case. Problems occur even with good bacteria when they are allowed to penetrate the inner confines of our bodies where they do not normally reside. This can happen during injury or when one is immune compromised (an AIDs patient for example). The intestinal flora is in many ways like inhabitants of a city. For the most part, they are calm. But, even in safe cities, unrest is possible and security is necessary to keep things under control. In our bodies, the immune system controls the bacterial masses. It bars their entrance into restricted areas of the body and controls their overgrowth.
Bad bacteria or pathogenic bacteria are different than the friendly bacteria making up one’s normal intestinal flora. Certain species are known for their ability to wreak havoc in the body despite one’s best defenses. Examples of these are Escherichia coli O157:H7 and Salmonella species, which cause food poisoning. Other examples are tetanus and Staphylococcus, which are potent disease inducers. Virulence factors are what makes some bacteria the bad boys and separates them from normal flora. Examples of virulence factors are the production of toxins or the ability to adhere to tissues internally.
Besides the effectiveness of B. subtilis in curing dysentery, there are a number of diseases where it is very clear that probiotics can be successfully applied. They are very effective for infectious diarrhea such as rotavirus-associated diarrhea and Clostridium difficile-related diarrhea. They are also helpful in antibiotic-induced diarrhea when antibiotics kill off the intestinal flora and leave it out of balance. And, it is clear that they work for vaginal yeast infections. There is also evidence that they are effective for constipation, irritable bowel syndrome, eczema and the common cold.
How do probiotics work?
It is proposed that there are three main possible modes of action for probiotics that make them beneficial.
1) Probiotics can make it more difficult for pathogenic bacteria to survive in the microenvironments of the body.
2) Probiotics can interact with the cells of the body and make them increase their defenses against invading microorganisms.
3) Probiotics can enhance the function of the immune system.
Caution is still necessary with probiotics
Though fermented foods containing probiotics, like yogurt, have been eaten for generations, caution with current supplements is advised. Unlike yogurt, which contains additional ingredients that may modulate the probiotic function in ways that we nothing about, most probiotic supplements just contain microorganisms and a few fillers. This means that the supplement could have a different effect on the body than the food alternative. Furthermore, some research has shown that the inflammatory status of the individual influences probiotic function.
Therefore, it is always wise to let a physician or nutritionist assess your unique personal health situation before forging ahead with a new program that includes probiotics.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment.
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