***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Diet is an important factor in colorectal carcinogenesis ; thus , dietary supplements may have a role in colorectal cancer prevention . OBJECTIVE The objective was to establish the relative luminal , epithelial , and epigenetic consequences of prebiotic , probiotic , and synbiotic dietary supplementation in humans . DESIGN This was a r and omized , double-blind , placebo-controlled , 4-wk crossover trial of resistant starch and Bifidobacterium lactis , either alone or as a combined synbiotic preparation , in 20 human volunteers . Rectal biopsy , feces , and serum sample s were collected . The rectal mucosal endpoints were DNA methylation at 16 CpG isl and loci and LINE-1 , epithelial proliferation ( Ki67 immunohistochemistry ) , and crypt cellularity . The fecal endpoints were short-chain fatty acid concentrations , pH , ammonia , and microbiological profiles ( by denaturing gradient gel electrophoresis and sequencing ) . Serum endpoints were a panel of cytokines and high-sensitivity C-reactive protein . RESULTS Seventeen subjects completed the entire study . The synbiotic intervention fostered a significantly different fecal stream bacterial community than did either the prebiotic ( P = 0.032 ) or the probiotic ( P = 0.001 ) intervention alone , in part because of a greater proportion of patients harboring fecal Lachnospiraceae spp . These changes developed in the absence of any significant differences in fecal chemistry . There were no differences in epithelial kinetics . CONCLUSIONS This synbiotic supplementation with B. lactis and resistant starch , in the doses used , induced unique changes in fecal microflora but did not significantly alter any other fecal , serum , or epithelial variables . This trial was registered in the Australian New Zeal and Clinical Trials Registry at www.anzctr.org.au as ACTRN012606000115538 Objective : This study investigated the effects of oral supplementation of resistant starch ( RS ) on tumour cell and colonic mucosal cell kinetics and on gene expression in patients with colorectal cancer ( CRC ) , and its potential role in colon cancer prevention . Methods : 65 patients with CRC were r and omised to treatment with RS or ordinary starch ( OS )  and were given starch treatment for up to 4 weeks . Pretreatment and post-treatment biopsies were obtained from the tumour and colonic mucosa , and the effects of the starch treatment on cell proliferation and expression of the cell cycle regulatory genes CDK4 ( cyclin-dependent kinase 4 ) and GADD45A ( growth arrest and DNA damage-inducible , alpha ) were investigated . Results : The proportion of mitotic cells in the top half of the colonic crypt was significantly lower following RS treatment ( 3.1 ( 1.5 ) , mean ( SEM ) ) as compared with OS treatment ( 13.7 ( 3.2 ) ) ( p = 0.028 ) . However , there was no effect of RS treatment on crypt dimensions and tumour cell proliferation index . There was significant upregulation in expression of CDK4 ( p<0.01 ) and downregulation in expression of GADD45A ( p<0.001 ) in the tumour tissue when compared with macroscopically normal mucosa . Following RS treatment , CDK4 expression in tumours ( 0.88 ( 0.15 ) ) was twofold higher than that in the OS group ( 0.37 ( 0.16 ) ) ( p = 0.02 ) . The expression of GADD45A , which was downregulated in the presence of cancer , was significantly upregulated ( p = 0.048 ) following RS treatment ( 1.41 ( 0.26 ) ) as compared with OS treatment ( 0.56 ( 0.3 ) ) . However , there were no significant differences in the expression of these genes in the normal mucosa following starch treatment . Conclusions : Cell proliferation in the upper part of colonic crypts is a premalignant marker and its reduction by RS supplementation is consistent with an antineoplastic action of this food component . Differential expression of the key cell cycle regulatory genes may contribute to the molecular mechanisms underlying these antineoplastic effects of RS . Trial registration number : IS RCT N93586244 BACKGROUND Animal studies suggest that prebiotics and probiotics exert protective effects against tumor development in the colon , but human data supporting this suggestion are weak . OBJECTIVE The objective was to verify whether the prebiotic concept ( selective interaction with colonic flora of nondigested carbohydrates ) as induced by a synbiotic preparation-oligofructose-enriched inulin ( SYN1 ) + Lactobacillus rhamnosus GG ( LGG ) and Bifidobacterium lactis Bb12 (BB12)-is able to reduce the risk of colon cancer in humans . DESIGN The 12-wk r and omized , double-blind , placebo-controlled trial of a synbiotic food composed of the prebiotic SYN1 and probiotics LGG and BB12 was conducted in 37 colon cancer patients and 43 polypectomized patients . Fecal and blood sample s were obtained before , during , and after the intervention , and colorectal biopsy sample s were obtained before and after the intervention . The effect of synbiotic consumption on a battery of intermediate bio-markers for colon cancer was examined . RESULTS Synbiotic intervention result ed in significant changes in fecal flora : Bifidobacterium and Lactobacillus increased and Clostridium perfringens decreased . The intervention significantly reduced colorectal proliferation and the capacity of fecal water to induce necrosis in colonic cells and improve epithelial barrier function in polypectomized patients . Genotoxicity assays of colonic biopsy sample s indicated a decreased exposure to genotoxins in polypectomized patients at the end of the intervention period . Synbiotic consumption prevented an increased secretion of interleukin 2 by peripheral blood mononuclear cells in the polypectomized patients and increased the production of interferon gamma in the cancer patients . CONCLUSIONS Several colorectal cancer biomarkers can be altered favorably by synbiotic intervention Background To systematic ally develop dietary strategies based on resistant starch ( RS ) that modulate the human gut microbiome , detailed in vivo studies that evaluate the effects of different forms of RS on the community structure and population dynamics of the gut microbiota are necessary . The aim of the present study was to gain a community wide perspective of the effects of RS types 2 ( RS2 ) and 4 ( RS4 ) on the fecal microbiota in human individuals . Methods and Findings Ten human subjects consumed crackers for three weeks each containing either RS2 , RS4 , or native starch in a double-blind , crossover design . Multiplex sequencing of 16S rRNA tags revealed that both types of RS induced several significant compositional alterations in the fecal microbial population s , with differential effects on community structure . RS4 but not RS2 induced phylum-level changes , significantly increasing Actinobacteria and Bacteroidetes while decreasing Firmicutes . At the species level , the changes evoked by RS4 were increases in Bifidobacterium adolescentis and Parabacteroides distasonis , while RS2 significantly raised the proportions of Ruminococcus bromii and Eubacterium rectale when compared to RS4 . The population shifts caused by RS4 were numerically substantial for several taxa , leading for example , to a ten-fold increase in bifidobacteria in three of the subjects , enriching them to 18–30 % of the fecal microbial community . The responses to RS and their magnitudes varied between individuals , and they were reversible and tightly associated with the consumption of RS . Conclusion Our results demonstrate that RS2 and RS4 show functional differences in their effect on human fecal microbiota composition , indicating that the chemical structure of RS determines its accessibility by groups of colonic bacteria . The findings imply that specific bacterial population s could be selectively targeted by well design ed functional carbohydrates , but the inter-subject variations in the response to RS indicates that such strategies might benefit from more personalized approaches The potential ' nutritional advantages ' of probiotics and prebiotics consist of preventive , and sometimes curative , effects against certain diseases . The evidence supporting such advantages , which requires r and omised controlled trials and consistency of results from study to study , is rapidly increasing . This article summarizes the effects against diseases of intestinal origin . There is a high level of evidence for positive effects of some prebiotics to alleviate  constipation  and treat  hepatic encephalopathy .  Interesting aspects , but with a lower level of evidence at the present time , include prevention of colon cancer , intestinal infection , and recurrence of inflammatory bowel disease . There is a high level of evidence for positive effects of some probiotics in the alleviation of lactose intolerance , antibiotic-associated intestinal disorders and gastroenteritis . Evidence is rapidly growing regarding the prevention of recurrence of inflammatory bowel diseases . Positive trials have suggested preventive effects against intestinal colonization with specific gut pathogens including Clostridium difficile and Helicobacter pylori Certain nondigestible oligosaccharides can be selectively utilized by probiotics and reduce the risk of colon cancer . However , the inhibitory effects of xylooligosaccharides ( XOS ) on colon cancer are not well documented . This study evaluated the effects of xylooligosaccharides and fructooligosaccharides ( FOS ) on the alteration of cecal microbiota , cecal pH , cecal weight , and serum lipid levels , and also their inhibitory effect on precancerous colon lesions in male Sprague-Dawley rats . The rats were r and omly assigned to 4 groups : control , treatment with 1,2-dimethylhydrazine ( DMH ) [ 15 mg/(kg body wt.wk ) for 2 wk ] , treatment with DMH + 60 g XOS/kg diet , and treatment with DMH + 60 g FOS/kg diet . Rats were fed the experimental diets for 35 d , beginning 1 wk after the second dose of DMH . Both XOS and FOS markedly decreased the cecal pH and serum triglyceride concentration , and increased the total cecal weight and bifidobacteria population . XOS had a greater effect on the bacterial population than did FOS . Moreover , both XOS and FOS markedly reduced the number of aberrant crypt foci in the colon of DMH-treated rats . These results suggest that XOS and FOS dietary supplementation may be beneficial to gastrointestinal health , and indicate that XOS is more effective than FOS BACKGROUND Nondigestible oligosaccharides have been cl aim ed to benefit the health of the colon by selectively stimulating the growth of bifidobacteria and by decreasing the toxicity of the colon contents . OBJECTIVE We compared the effect of 2 doses of transgalactooligosaccharides and a placebo on the composition and activity of the intestinal microflora in 18 women and 22 men . DESIGN Strictly controlled experimental diets were supplied to 3 intervention groups in a parallel design . The study was divided into 2 consecutive 3-wk periods during which each participant consumed a run-in diet followed by an intervention diet that differed only in the amount of transgalactooligosaccharides : 0 ( placebo ) , 7.5 , and 15 g/d . Breath sample s and fecal sample s were collected at the end of both the run-in and intervention periods . RESULTS Apparent fermentability of transgalactooligosaccharides was 100 % . The highest dose of transgalactooligosaccharides significantly increased the concentration of breath hydrogen by 130 % ( P < 0.01 ) and the nitrogen density of the feces by 8.5 % ( P < 0.05 ) . The number of bifidobacteria increased after both placebo and transgalactooligosaccharides ingestion , but the differences between these increases were not significantly different . Transgalactooligosaccharides did not significantly affect bowel habits ; stool composition ; the concentration of short-chain fatty acids or bile acids in fecal water ; the concentration of ammonia , indoles , or skatoles in feces ; fecal pH ; or the composition of the intestinal microflora . CONCLUSION We conclude that transgalactooligosaccharides are completely fermented in the human colon , but do not beneficially change the composition of the intestinal microflora , the amount of protein fermentation products in feces , or the profile of bile acids in fecal water BACKGROUND Nondigestible carbohydrates ( NDCHs ) are fermented in the colon , where they can selectively promote the growth of bifidobacteria . OBJECTIVE Our aim was to determine the bifidogenic potential of different NDCHs used in human diets . DESIGN Two hundred healthy volunteers participated in this double-blind study . During phase 1 ( screening ) , 64 volunteers were r and omly assigned to 8 groups of 8 subjects each ; for 7 d , they ingested 10 g/d of 1 of the 7 NDCHs tested or of the placebo . During phase 2 ( dose-response study ) , 136 volunteers were r and omly assigned to 4 groups of 32 subjects who received 2.5 , 5.0 , 7.5 , or 10 g/d , respectively ( 8 subjects/dose ) , of one of the NDCHs that were proven to be b 
    Output:
    
Lactulose reduced adenoma recurrence , while resistant starch had no effect on adenoma or CRC development .
Crypt mitotic location , gene expression , and DNA methylation were somewhat improved after resistant starch consumption .
No changes in cell proliferation and apoptosis , crypt morphology , or aberrant crypt foci were found .