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Health claims and Mechanisms of action

Prebiotics affect intestinal bacteria by increasing beneficial anaerobic bacteria and decreasing pathogenic
microorganisms. Probiotics affect the ecosystem by stimulating mucosal immune mechanisms and through
non-immune mechanisms, such as antagonism and competition with pathogens.

The normal gut bacteria-host interaction is symbiotic. Upper intestinal bacteria exert an important influence
on immune function. The intestine is the body's most important immune-related organ, with approximately
60% of the body's immune cells present in the intestinal mucosa. The immune system controls responses
against dietary proteins (preventing food allergies) and pathogenic microorganisms (viruses, bacteria,
parasites).

Clinical applications

• Colon cancer: Probiotics reduce colon cancer risk in animal models, possibly by suppressing bacterial

enzymes that increase procarcinogen levels, though this is unproven in humans. Synbiotics may

decrease the expression of colorectal cancer biomarkers.

• Diarrhea: Some probiotic preparations are used to prevent and treat acute diarrhea, antibiotic-

associated diarrhea, and radiation-induced diarrhea.

• Eradication of Helicobacter pylori: Supplementing anti-H. pylori antibiotic regimens with certain

probiotics may increase eradication rates and may be helpful for patients who have experienced

eradication failure. There is insufficient evidence that probiotics alone are effective.

• Allergy: Prevention of atopic dermatitis has been observed when certain probiotics are given to

pregnant mothers and to newborns for the first 6 months of life.

• Hepatic encephalopathy: Prebiotics like lactulose are commonly used to prevent and treat this

complication of cirrhosis. Minimal hepatic encephalopathy was reversed in 50% of patients treated for

30 days with a synbiotic preparation.

• Inflammatory bowel disease (IBD):

o Pouchitis: There is good evidence for probiotics in preventing an initial attack of pouchitis

(inflammation of a surgically created ileal pouch post-colectomy) and in preventing relapse.

o Ulcerative colitis: The probiotic E. coli Nissle strain may be equivalent to mesalazine in

maintaining remission.

• Irritable bowel syndrome (IBS): A reduction in abdominal bloating and flatulence from probiotic

treatment is a consistent finding. Some strains may also ameliorate pain.

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