For the past couple of months, I have received several questions concerning probiotics, what are they and why or if we should use them. Probiotics seem to be appearing more on the shelves of health food stores and, as such, the research is steadily increasing. When I went to the store to get an idea of how many there are, I was completely overwhelmed. No wonder there is so much confusion about probiotics! Those shelves are loaded with so many brands and names that who could keep them all straight? Is there any reason to have that many brands? Lets see…
What are probiotics?
Probiotics are a group of live microorganisms including Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus species and yeasts, that may beneficially affect the body upon ingestion by improving the balance of the body’s microflora (i.e. bacteria that are naturally occurring in the small and large intestine, mouth and vagina). The scope of this article will be focused on the benefits of probiotics for our intestine.
Thus far, scientists suggest that a healthy human digestive tract contains about fourteen various types of genus of microorganisms, making a grand total of approximately 400 types of bacteria that reduce the growth of harmful bacteria and promote a healthy digestive system.
The largest group of probiotic bacteria in the intestine is lactic acid bacteria, of which Lactobacillus acidophilus, found in yogurt, is the best known however, there are other species of Lactobacillus that have been shown to be beneficial. The genus Lactobacillus is lactic-acid producing bacteria that thrive in the presence of lactose, a sugar
found in dairy products such as cheese and yogurt.
Élie Metchnikoff, the father of modern immunology, believed the health benefits of the lactic acid-bacteria Lactobacillus bulgaricus and Streptococcus thermophilus could prolong life at the turn of the 20th century. He wrote in his book, The Prolongation of Life: Optimistic Studies, that consumption of live bacteria, such as L. bulgaricus and S. thermophilus, in the form of yogurt was beneficial for gastrointestinal health, as well as for health in general, and for longevity. He “proved” his theory by drinking sour milk daily and dieing at the ripe age of 71, well above the average life expectancy in 1916.
Mention of cultured dairy products is found in the Bible and the sacred books of Hinduism. Soured milks and cultured dairy products, such as kefir, koumiss, leben and dahi, were often used therapeutically before the existence of microorganisms was recognized.
The Function of Microbes in the GI Tract
The gastrointestinal (GI) tract of animals represents a complex ecosystem in which a delicate balance exists between the intestinal microflora and the host. The host and micoflora live in a synergistic environment – the host providing a comfortable environment for the microbes to survive while the microbes thrive and produce beneficial metabolic byproducts that aid the host’s GI tract and immune system.
This synergistic relationship begins developing while breastfeeding from our mother and receiving kisses from family and friends while we are babies. The inhabitation of microbes in a developing GI tract is proving to be important not only in the neonatal period and during infancy, but it is becoming increasingly evident that microbial colonization in early life may affect the individual’s health throughout life.
The small intestine is lined with lymph nodes that support our immune system. The byproducts and metabolites of the intestinal microflora are important for maturation of the immune system, the development of normal intestinal form and structure and in order to maintain a chronic and immunologically balanced inflammatory response. The microflora reinforce the barrier function of the intestinal lining, helping in the prevention of the attachment of pathogens and the entry of allergens. Some members of the microflora may contribute to the body’s requirements for certain vitamins, including biotin, pantothenic acid and vitamin B12. Alteration of the microbial flora of the intestine, which may occur with antibiotic use, disease/sickness and aging, can negatively affect its beneficial role. This is where the potential benefits of supplementing with probiotics may enter in order to balance what the antibiotics, disease/sickness or aging destroyed.
Uses and Mechanisms of Probiotics
In most circumstances, people use probiotics to prevent diarrhea caused by antibiotics. Antibiotics kill “good”(beneficial) bacteria along with the bacteria that cause illness. An imbalanced ratio of “bad”:”good” bacteria may lead to diarrhea. It has been hypothesized that taking probiotic supplements (as capsules, powder, or liquid extract) may help replace the lost beneficial bacteria and thus help prevent or treat diarrhea. Consumption of a probiotic drink containing L. casei, L. bulgaricus, and S. thermophilus has been shown to reduce the incidence of antibiotic associated diarrhea and Clostridium difficile associated diarrhea. Supplementation of infant formula milk with B. bifidum and S. thermophilus reduced diarrhea caused by a rotavirus in children.
The antimicrobial activity of probiotics is thought to be accounted for, in large part, by their ability to colonize the
colon and reinforce the barrier function of the intestinal mucus membranes.
In infants infected with rotavirus, L. casei, L. acidophilus and B. bifidum have been shown to enhance the “eating ability” (i.e. phagocytic activity) of various circulating white blood cells, perhaps via an increase in the levels of circulating immunoglobulin A (IgA), an antibody that aids in the removal of a chemical or organism.
In healthy individuals, L. salivarius and L. johnsonii have also demonstrated to produce an increase in the phagocytic activity of circulating white blood cells. This shows it is nice to know that you do not have to have an infection in order to receive any benefits of certain probiotics. With this in mind, this would place taking
probiotics as more of a preventative measure.
L. casei and L. rhamnosus, have even shown anti-tumor activity by inhibiting the initiation and/or promotional
events of the chemically-induced tumors in rats and by actually binding to some chemical carcinogens.
Other probiotics, such as Saccharomyces boulardii, are believed to have their protective effects by digesting the
toxins that infectious bacteria create. S. boulardii has been found to secrete a protease which digests two protein
exotoxins, toxin A and toxin B, which appear to mediate diarrhea and colitis caused by C. difficile. S. boulardii is usually given to those who get antibiotic-induced diarrhea.
Probiotics that colonize the colon may be helpful in the management of some people with food allergies by
maintaining optimal functioning of the mucosal layer. L. rhamnosus and B. lactis were found to produce significant
improvement of atopic eczema in children with food allergies.
Finally, perhaps the beneficial effects of some of the probiotics mentioned in this article are because of their anti-oxidant abilities, which include chelation (i.e. binding a substance to a toxic metal, such as iron or copper), binding to reactive free-radicals and reducing free-radical activity.
When to Use Probiotics
If you believe that probiotics may be beneficial for you, but you do not know what to look for on a product’s label to
help with your condition, here is what the research has to say.
Antibiotic-Related Diarrhea. Among the probiotics, only S. boulardii, Enterococcus faecium and Lactobacillus species have been useful in preventing antibiotic-related diarrhea. S. boulardii appears to be the most superior form of treatment when
diarrhea is caused by C. difficile. The use of probiotics in the attempted prevention and treatment of traveler’s diarrhea, most commonly caused by an E. coli toxin, has produced inconclusive results. The results of some early studies suggest that probiotics found in yogurt may help prevent diarrhea caused by antibiotics. However, more studies are needed to confirm that yogurt is effective. To offer benefit, the yogurt must contain active cultures. Most yogurt containers indicate whether active cultures are present.
Anti-Inflammatory for GI Conditions. Because of a reduced fecal concentration of various probiotics in individuals with active ulcerative colitis, Crohn’s disease, active pouchitis, inflammatory bowel disease, and irritable bowel syndrome, researchers have noted that probiotics may be beneficial for individuals with these conditions. However, thus far, the results are inconclusive and more research is needed.
Allergies. Some lactic acid bacteria, including L. plantarum, L. rhamnosus, L. casei and L. bulgaricus, have demonstrated immunoregulatory effects that might help protect against some allergic disorders. There is some
evidence that some of these probiotic strains can reduce the intestinal inflammation associated with some food
allergies, including cow’s milk allergy among babies. Breastfed infants of nursing mothers given Lactobacillus
had significantly improved atopic dermatitis or eczema, compared with infants not exposed to this probiotic.
Anti-Carcinogenic. There are in vitro, animal and some preliminary human data suggesting that some probiotics
can bind and inactivate some carcinogens, can directly inhibit the growth of some tumors and can inhibit bacteria
that may convert pre-carcinogens into carcinogens. L. acidophilus and L. casei have exhibited the latter activity in
human volunteers. There is some preliminary evidence that L. casei may have reduced the recurrence of bladder
tumors in humans. Confirmatory trials are needed. Animal work has suggested that some lactic-acid bacteria might
help protect against colon cancer. Again, more research is needed.
Lower Cholesterol. Dairy products containing L. acidophilus have been credited with lowering cholesterol levels in some animal experiments. It has been hypothesized that bacterial assimilation of cholesterol in the intestine might
reduce cholesterol stores available for absorption into the blood. To date, there is no credible evidence showing that
any of the probiotics can lower cholesterol levels in humans. More study may be warranted.
Summary
The effectiveness of probiotics is dependent upon their ability to survive in the acidic stomach environment and
the alkaline conditions in the upper small intestine, as well as their ability to adhere to the intestinal mucosa of the
colon and to colonize the colon. Some probiotics, such as L. casei, L. rhamnosus, and L. plantarum, are better able to colonize the colon than others.
A major problem is that there are many probiotic products available, and not all of them have been tested for every
potential treatment listed above. These products contain various Lactobacillus strains, various Bifidobacterium
strains, combinations of lactobacilli and bifidobacteria and combinations of probiotics and prebiotics. Typical doses of probiotics range from one to ten billion colony-forming units (CFU) a few times a week. Whether or not you should have more of one that another is unknown exactly, but I have provided a couple of examples of diseases/ailments that you may want to try using probiotics in order to prevent/cure.
Because of the inconclusive data of probiotics, we still do not know what is the optimal number of CFU’s that should be administered for a healthy GI tract. As mentioned earlier, there are approximately 400 species of bacteria alone in our gut, and I have not even mentioned the number of fungi or archaea that are present and how these may interact with our immune system and other bacteria. The idea that we are always “balancing” our gut with probiotics should be used with caution considering that if you are adding more bacteria to an unknown concentration of microbes, one does not know if it is actually helping or not, depending on the circumstances. Trial-and-error are needed on an individual basis, and this will require trying an assortment of probiotic products. Also, if you eat foods with active bacteria, such as kimchi and sauerkraut (both contain high amounts of lactic-acid forming bacteria), you are constantly affecting the microflora concentration of your gut; and the majority of the research suggests it is for the better. The animal and in vitro studies continually show promise that there may be more benefits of probiotics around the corner.
Probiotics need to be consumed at least a few times a week to maintain their effect on the intestinal microecology. Overall, I would suggest getting as much variety in your diet and trying various probiotic products, almost on a monthly rotation, to get as many benefits from these products as possible while not getting too much of a certain species of bacteria over another. Happy shopping!
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