1、Effects of Probiotics on Human Health and MechnismsTong-Cun Zhang,Ph.DTianjin Univ.of Science&TechnologyOutline What are probiotics？How do they work？Current proposed uses and a look at some of the evidence Issues in prescribing their useProbiotics concept Probiotics are defined as living micro-organ
2、isms,which upon ingestion in certain numbers exert health benefits beyond general nutritionIntensive research area in the world.Probiotics Lactobacillus sp.reuteri casei ramnosus acidophilus Streptococcus sp.Bifidobacterium sp.infantis lactis longum breve Sacharomyces boulardii(non-human)Acid tolera
3、nce Bile tolerance Cell surface hydrophobicity Protoplast regeneration Antimicrobial activity Cholesterol removal and bile salt deconjugation Gut colonization Lactose removal Protease and aminopeptidase activityProbiotics attributesProbiotics:Proposed usesInfectious diarrheaAntibiotic-associated dia
4、rrheaIBD,IBS,and pouchitisNecrotizing EnterocolitisBacterial vaginosisRecurrent UTIsAtopic diseasesImmune system enhancementH pylori infectionsDental cariesRadiation induced diarrheaCardiovascular risk reductionConstipationRheumatoid arthritisProbiotics:Proposed usesRating the EvidenceFloch et al(20
5、06)Natural Standard(2006)Infectious diarrheaABAntibiotic-associated diarrheaACDiarrhea preventionBBIBSCBAtopic dermatitis/AllergyB?B/CRatings:A:strong B:good C:fairFloch,et al.Recommendations for Probiotic Use.J Clin Gastro.40(3)Probiotics:Proposed usesRating the EvidenceFloch et al(2006)Natural Sta
6、ndard(2006)Ulcerative colitisCBCrohns diseaseCH pylori infectionCANECCBacterial vaginosisCCUTIsCRatings:A:strong B:good C:fairFloch,et al.Recommendations for Probiotic Use.J Clin Gastro.40(3)Probiotics:the evidenceAntibiotic-associated diarrhea:DSouza et al(BMJ 2002)Systematic review of 9 placebo-co
7、ntrolled studies(2 in children)Various probiotics(4 uses S Bouladarii)60%reduction in antibiotic associated diarrhea compared with placebo(OR 0.37,95%CI 0.26-0.53)Vanderhoof et al(J Pediatr 1999)202 children,6 mo-10 yr,otitis/pharyngitis,amox/amox-clav Oral antibiotics in an outpatient setting for 1
8、0 days Lactobacillus GG,10(12kg)billion cfus for 10 d Rated stool consistency and frequency 26%of controls and 8%of L GG had diarrhea Of those with diarrhea,5.9 days in placebo,4.7 days in L GGProbiotics:the evidenceInfectious diarrhea:Van Niel et al(Peds 2002)Systematic review of 9 studies(all outs
9、ide US,1-36 months)Various probiotics(4 used L GG)Mean reduction in diarrhea of 0.7 days(95%CI:0.3-1.2)1.6 fewer stools in L GG groups(95%CI:0.7-2.6)Dose response curve with higher L GG doseTwo other meta-analyses also showed benefits,particularly with L GG Allen et al.Cochrane Database Syst Rev,200
10、4 Szajewska et al.J Pediatr Gastroenterol Nutr,2001Probiotics:the evidencePrevention of infections in day care:Weizman et al(Peds 2005)Double-blind,placebo-controlled RCT 14 day care centers in Israel,4-10 months of age Formula with B lactis,L reuteri,or no probiotics(no breastfeeding)Mean intake:1
11、billion orgs Intervention and follow-up totaled 12 weeks Both probiotic groups had:Fewer febrile episodes Fewer diarrhea episodes Shorter diarrhea episodes No difference in rate or duration of respirator illnesses L reuteri group did significantly better than B lactis groupProbiotics:the evidenceAto
12、pic disease:Kalliomaki et al(Lancet 2001)L GG,10 bill cfus,given to mothers with a family hx of a first degree relative with an atopic condition(asthma,eczema,allergic rhinitis).Mothers for 2-4 weeks before delivery,then infants or lactating mothers for the first 6 months.Outcome:atopic disease at 2
13、 yrs.Frequency of eczema reduced from 46%to 23%(RR 0.51,CI:0.32-0.84)Kalliomaki et al(Lancet 2003)4 yr follow up study(54 of 68 controls,53 of 64 intervention)Relative risk reduction for atopic eczema of 0.57(95%CI:0.33-0.97)Probiotics:prescribing Which organism to use?Which product?For what conditi
14、ons?What dose?For How long?Any side effects to be aware of?How much does it cost?Take home pointsGood evidence for:Infectious diarrheaAntibx-assoc diarrheaPromising evidence for:Prevention of infectious diarrheaPrevention of atopic conditionsother uses?In the future we may be using probiotics as we
15、use antibiotics today:with specific strains used for certain clinical situations guided by controlled studiesPrescribing Lactobacillus GG best studied to date Combination products not well studied,but may work as well 10 billion organisms/d Keep in fridge Give in cool food/drink 2%risk bloating/gasB
16、acteriocinBioactive peptidesShort chain fatty acidsNeutralization of dietary carcinogensFree amino acidsOrganic acids-Galactosidase activityOligosaccharidesCholesterol assimilationSurvival and adhesion competitions with pathogenic bacteriaAntioxidantImmunostimulatoryProbioticsPotential Benefits of PrebioticsProblems No double blind control tests about the effects Genomes of Probiotics are still unclear Research Methods need to be improved No lots of Validate markers used for assessing probiotic functionQuestions？
