The Health Benefits of Probiotics: an Overview

Benefits of probiotics

The notion of consuming bacteria to treat or cure disease may, at first thought, seem counter-intuitive. After all, weren’t we always taught to wash our hands before we sat down for a meal or disinfect a cut–all to cut the risk of a bacterial infection? A little perspective: despite our best efforts to get rid of the microorganisms, our body actually houses trillions of bacteria (which, by some estimates, outnumbers human cells 10 to 1). These bacteria are not all pathogenic (that is, cause disease); in fact, some bacteria–the “good” bacteria–are essential in maintaining proper health and warding off disease. Often, health complications and diseases arise when the body’s bacterial ecosystem, the microbiome­, become imbalanced and the pathogenic bacteria begin to outnumber the “good” bacteria.

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Probiotics (literally translating to “for life”) are the body’s “good” bacteria–those that benefit health when taken in adequate amounts. So what exactly are the health benefits of probiotics? Since the mid 1990’s, probiotic therapy has been shown to help treat some gastrointestinal disorders (primarily acute and antibiotic associated diarrhea), delay incidence of allergies in infants and children, and alleviate or treat vaginal/urinary infections in women.

Clinically Established Probiotic Benefits

Probiotics have shown efficacy against a number of clinical indications. Here, we provide a short overview of each one and the strains associated with the mentioned benefits.

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Lactose Intolerance: Lactase, the enzyme responsible for the breakdown of lactose, is produced during the fermentative process during yogurt production. Studies have found that feeding yogurt to lactose-intolerant individuals significantly improved lactose metabolism and reduced symptoms of lactose intolerance. According to a clinical review, the strains most often included in yogurt production include Lactobacillus bulgaricus and Streptococcus salivarius subsp. thermophilus.

Acute/Antibiotic-associated/Traveler’s Diarrhea: Despite the etiology of diarrhea (bacterial infection, antibiotic-mediated disturbance of intestinal microflora composition, or travelling to warmer/less developed countries), probiotics have shown clear benefit in the treatment of diarrhea in adults and children. According to a clinical review, the strains that have shown efficacy include Lactobacillus rhamnosus strain GG, Lactobacillus reuteri, and Saccharmoyces bouldarii.

Allergies: Some allergies, including atopic eczema and atopic dermatitis (and possibly allergic rhinitis), have shown improvement after probiotic intervention. According to a clinical review, the strains that have shown efficacy include Lactobacillus GG, Bifidobacterium animalis, and Bifidobacterium lactis.

Clostridium difficile Infection: Antibiotic treatment may disrupt floral balance in the intestine and result in the overgrowth of C. difficile, a bacterium associated with symptoms ranging from diarrhea to life-threatening gastroenteritis. According to a clinical review, Lactobacillus GG treatment (2 cycles) resulted in cure rates as high as 94%.

Dental carries: Probiotic administration (Lactobacillus GG in this study) resulted in reduced incidence of dental carries (cavities) and lower counts of Streptococcus mutans, one of the bacteria responsible for cavity development, in young children.

Inflammatory Bowel Disease (IBD)/Irritable Bowel Syndrome (IBS): Small studies have previously shown that patients suffering from IBD had fewer relapses and reduced use of steroids (which help manage the symptoms of IBD) after probiotic intervention. According to a clinical review, the strains that have shown efficacy include Lactobacillus salivarius, Escheria coli strain Nissle, Streptococcus bouldarii, and VSL#3 (a probiotic mixture).

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Future Directions

There have been reports or probiotic’s beneficial effects on a variety of other illnesses, though these reports are based on inconclusive evidence (animal studies, preliminary human studies, uncontrolled studies, or anecdotal speculation). These indications include prevention/treatment of joint disease associated with rheumatoid arthritis, inhibiting the initiation or progression of colon and bladder cancers, prevention of liver cancer (aflatoxin-mediated) and ethanol-induced liver damage, and lowering levels of hemoglobin A1c and improving glucose tolerance in diabetics. These results show promise for the potential benefit of probiotic therapy, but further research is needed to draw definitive conclusions.