A number of studies have been performed examining the influence of various probiotic organisms, either alone or in combination, on immune parameters, infectious outcomes, and inflammatory conditions in humans. Some components of the immune response, including phagocytosis, natural killer cell activity and mucosal immunoglobulin A production (especially in children), can be improved by some probiotic bacteria.

Probiotics are beneficial living microorganisms that support healthy gastrointestinal and immune systems. Hundreds of diverse microbial species, some essential for health, others pathogenic, inhabit or pass through the gastrointestinal tract. In a healthy digestive system, these microorganisms coexist in a balanced harmony.

Research has shown that diverse probiotic strains are able to inhibit the growth and control populations of pathogenic microbes by competing for nutrients and adhesion sites, producing anti-microbial compounds such as organic acids, hydrogen peroxide and bacteriocins, and stimulating the body’s own healthy immune responses. Probiotics have been found to favorably modulate the immune system locally in the bowel mucosa, distantly at mucosa surfaces throughout the body, and systemically.
Probiotic microorganisms maintain and strengthen intestinal barrier function as well as regulate bowel motility. They promote normal colonic blood flow, produce essential nutrients for the colon mucosa, synthesize vitamin K and B vitamins, and facilitate nutrient and mineral absorption, especially calcium, magnesium and zinc. Probiotics degrade and detoxify carcinogenic enzymes and other molecules as well as hormones and drugs.

Probiotics have been clinically shown to support against respiratory and skin allergies by virtue of their immune effects systemically and at mucosal surfaces outside the bowel. Most strains effectively reduce lactose intolerance and many can degrade endogenous opioids. An emerging hypothesis suggests that probiotics may play an important, complementary role in detoxification protocols.

The standard Western diet is deficient in the essential probiotics needed to maintain health. Highly processed, canned, and frozen foods lack the healthful microorganisms the body requires for a normally balanced microflora. As a consequence, most people in North America and Western Europe lack important probiotic bacteria normally found in healthy people consuming a diet based on plants, fibers, fresh fruits, and vegetables. In addition, the normal intestinal balance of microorganisms can be disrupted by stress, disease, poor nutrition, toxins, and medications, such as antibiotics, immunosuppressants, and gastric acid inhibitors, resulting in intestinal and systemic health disturbances. Probiotic nutritional supplementation can support the body in restoring and maintaining a healthy, balanced gastrointestinal microflora.

Lactobacillus acidophilus

Antagonizes a wide range of pathogenic bacteria. Reduces intestinal concentrations of carcinogenic enzymes.
Highly resistant to gastric acid, bile, pepsin, and pancreatin. Possesses more than 20 known peptidases and breaks down casein and gluten. Ferments lactose and metabolizes a variety of other sugars and polysaccharides.

Lactobacillus rhamnosus

Produces more peptidases than any other Lactobacillus species. Favorably enhances innate and acquired immunity. Inhibits proinflammatory cytokine production. Outstanding colon epithelial cell adherence. Suppresses pathogenic Escherichia coli internalization. Antagonizes rotavirus and Clostridium difficile. Supports gut microflora during antibiotic therapy. May support immune function in infants with allergies.

Lactobacillus casei
An adaptive transient species. Makes many proline-specific peptidases enhancing casein, casein-derived polypeptide, and gluten break down. Beneficially modulates innate immune responses. Decreases proinflammatory cytokine secretion. Inhibits E. coliadherence to and invasion of intestinal cells. Decreases Shigella-mediated inflammation. Increases the number of intestinal IgA-producing cells. Antagonizes Helicobacter pylori.

Lactobacillus salivarius

Indigenous to the intestinal tract and other mucosal surfaces. Secretes several anti-microbial agents. Reduces proinflammatory cytokine secretion. Attenuates inflammatory responses to Salmonella typhimurium. Stimulates interleukin-10 secretion, a cytokine inhibiting the inflammatory response to bacterial DNA. Enhances intestinal calcium uptake. Significantly supports intestinal barrier function.

Lactobacillus plantarum

A highly beneficial transient bacteria generally lacking in people consuming a standard Western diet while universally present in people consuming traditional plant-based diets. Supports intestinal barrier function. Reduces translocation of gut bacteria. Antagonizes C. difficile. Supports normal microflora in people with irritable bowel syndrome. Exceedingly resistant to gastric acid and bile salts. Facilitates induction of the central regulatory cytokine, interleukin-12. Decreases production of inflammatory mediators.

Lactobacillus paracasei 
Excellent acid-tolerance. Highly resistant to pancreatin. Ferments inulin and phleins and produces high levels of lactic acid. Antagonizes C. difficile and Staphylococcus aureus as well as other pathogens. Contributes to a healthy vaginal microflora. Has supportive benefit in conditions ranging from allergic rhinitis to nonrotavirus diarrhea in children.

Lactobacillus brevis 
A colonizing species producing lactate, carbon dioxide, ethanol, and acetate. Resistant to gastric acid, bile acids, and digestive enzymes. Excellent adherent properties. Metabolically unique in the production of arginine deaminase to break down arginine and reduce polyamine production, compounds associated with vaginal dysbiosis and intestinal carcinogenesis. Increases production of interferon.

Bifidobacterium bifidum

Present in large numbers in a healthy colon. Populations are reduced in allergic infants and decline significantly with age. Suppresses total and antigen-specific IgE production. Enhances IgM and IgG responses to select antigens. Activates B cell IgA secretion. Enhances IgA response to C. difficile toxin A. Along with L. acidophilus, supports gut microflora during antibiotic therapy and reduces positive testing for C. difficiletoxins.

Bifidobacterium infantis

Frequently found in infants’ intestinal tracts, but rarely in older adults. Strong suppressive effect on Bacteroides vulgatus, a commensal bacteria thought to have a role in inflammatory bowel disease. Together with L. acidophilus, supports the gut microflora in very low birth weight infants decreasing the risk of necrotizing enterocolitis and promotes normal microflora in children with diarrhoea. Reduces proinflammatory cytokine production. Supports normal microflora and inflammatory cytokine ratios in patients with irritable bowel syndrome.

Bifidobacterium longum

Often the dominant Bifidobacterium species in humans. Ferments a broad spectrum of oligosaccharides. Resistant to high bile salt concentrations. Inhibits enterotoxigenic E. coli receptor binding and translocation. Augments intestinal IgA secretory response to dietary proteins. Favorably modulates inflammatory cytokine response to respiratory antigens. Improves inflammation in ulcerative colitis.  Inhibits human neutrophil elastase which may be important to innate immunity and attenuate harmful intestinal inflammation.

Bifidobacterium breve

Secretes compounds, such as lactosidase, that favorably modify intestinal microflora by reducing Bacteroides and Clostridiumconcentrations and degrading mucin. Eliminates stool Campylobacter jejuni in campylobacter enteritis restoring normal intestinal microflora. Antagonizes rotavirus and decreases rotavirus shedding in infants with rotavirus diarrhea. Stimulates Peyer’s patch B cell proliferation and antibody production.

Streptococcus thermophilus

A transient species with a long history of use as a starter culture for yogurt and cheese. Highly adapted to lactose metabolism. Many fermentation end-products including formate, acetoin, acetylaldehyde, diacetyl, and acetate that inhibit pathogenic bacterial proliferation. Reduces DNA damage and premalignant lesion formation by protecting against carcinogens. Along with other probiotics supports normal microflora and gastrointestinal function in conditions ranging from rotavirus diarrhea in infants to remission in ulcerative colitis.

Lactobacillus bulgaricus

A highly adapted, transient species closely related to L. acidophilus. Along with S. thermophilus, it has long been used in the production of yogurt and cheese. Supports normal cholesterol levels and reduces low density lipoprotein cholesterol oxidation. Suppresses proinflammatory cytokine production.

Lactobacillus gasseri
Native to the human gut and vaginal tracts of healthy women and normally present in human breast milk. Produces hydrogen peroxide and bateriocins inhibitory to Clostridium, Listeria, and Enterococcus. Protects against intestinal mitogens and carcinogens.

Bifidobacterium lactis
Produces large amounts of anti-microbial formate. Enhances leukocyte tumor cell-killing properties and phagocytic activities. Increases numbers of total, helper, and activated T cells. B. lactis significantly increases serum and mucosal IgA responses to cholera toxin and tetanus toxoid.

Saccharomyces boulardii
Hardy, nonpathogenic yeast. Broad antimicrobial activities against C. dificile, toxigenic E. coli, Candida, and other gastrointestinal pathogens. Augments colon bifidobacteria populations and increases butyrate concentrations. Enhances brush border enzyme activities and improves gut barrier function.