Effect of Probiotics in Allergy
Live organisms that survive passage through the gastrointestinal tract and provide beneficial effect to the individual are referred to as probiotics. These organisms are part of the natural flora of the small and the large intestine. Some common probiotic bacteria that have been isolated from the gut passage and scientifically studied include Lactobacillus rhamnosus GG, Lactobacillus acidophilus, Lactobacillus longum, Lactobacillus reuteri, Lactobacillus plantarum, and Bifidobacteria lactis Bb12.  Clinical studies conducted in many parts of the world show that probiotics if consumed over several months, are able to improve the symptoms of IgE-mediated allergy. In addition they are able to enhance the activity of the immune system. Only a selected group of probiotic bacteria have health-promoting activity. Most of the probiotic bacteria do not have beneficial effect and some may have negative effect. Moreover, a combination of probiotics is not necessarily the best choice since one species of bacteria will often interfere in the health-promoting activity of other probiotic bacteria. Recent studies show pure cultures of selected bacteria (e.g. Lactobacillus rhamnosus GG) taken daily may benefit the patient. Unfortunately orally taken probiotics cannot establish a niche in the gastrointestinal tract as soon as the oral intake is stopped. This means that persons who derive benefit from the intake of probiotics must continue to take the supplement daily. The Table below lists some strains of probiotics that have been identified to suppress the symptoms of allergy.

 

Table: ACTIVITY OF PROBIOTICS
Microflora	Action associated with the Probiotics
Lactobacillus rhamnosus GG	Reduced duration and risk of (a) rotavirus diarrhoea, (b) acute gastroenteritis diarrhoea, (c) formula milk-fed diarrhoea, (d) Clostridium difficile diarrhoea, (e) antibiotic-associated diarrhoea, and (f) traveller’s diarrhoea. Increased production of secretory IgA antibody. Prevent recurrent urinary tract infections and chronic vaginitis. Reduce food allergies and atopic dermatitis. Increased anti-inflammatory interleukins (IL-10, TGF-beta) production. Reduced bloating, flatulence and pain in irritable bowel syndrome
Lactobacillus longum	Reduced duration and risk of (a) rotavirus diarrhoea, (b) acute gastroenteritis diarrhoea, (c) formula milk-fed diarrhoea, (d) Clostridium difficile diarrhoea, (e) antibiotic-associated diarrhoea, and (f) traveller’s diarrhoea. Increased production of secretory IgA antibody. Prevent recurrent urinary tract infections and chronic vaginitis. Reduce food allergies and atopic dermatitis. Increased anti-inflammatory interleukins (IL-10, TGF-beta) production. Reduced bloating, flatulence and pain in irritable bowel syndrome
Lactobacillus plantarum	Reduced incidence of diarrhea in children. Reduced bloating, flatulence and pain in irritable bowel syndrome
Lactobacillus reuteri	Reduced duration and risk of (a) rotavirus diarrhoea, (b) acute gastroenteritis diarrhoea, (c) antibiotic-associated diarrhoea, and (e) traveller’s diarrhoea. Role in allergy unknown.

 

Clinical studies performed in several hospitals in different parts of the world have shown that probiotics have many health-promoting activities in the gut including: (1) Enzymatic degradation of antigens in gut making them less allergenic, (2) Preventing attachment of pathogenic bacteria to the gut epithelium reducing infections, (3) Repairing permeability barrier of the gut and inhibiting allergens transfer into body, (4) Suppression of the pro-inflammatory responses elicited by the pathogenic gut bacteria, (5) Promoting maturation of Th1-type  immune cells, (6) Production of factors that encourage multiplication of other gut resident probiotics, and (7) Modulating the immune response and promoting the development of oral tolerance to food and other antigens in the gut.