***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 
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    Input: Background Diverticulosis and its complications are important healthcare problems in the USA and throughout the Western world . While mechanisms as to how diverticulosis occurs have partially been explored , few studies examined the relationship between colonic gases such as methane and diverticulosis in humans . Aim This study aim ed to demonstrate a significant relationship between methanogenic Archaea and development of diverticulosis . Methods Subjects who consecutively underwent hydrogen breath test at Rush University Medical Center between 2003 and 2010 were identified retrospectively through a data base . Medical records were review ed for presence of a colonoscopy report . Two hundred and sixty-four subjects were identified who had both a breath methane level measurement and a colonoscopy result . Additional demographic and clinical data were obtained with chart review . Results Mean breath methane levels were higher in subjects with diverticulosis compared to those without diverticulosis ( 7.89 vs. 4.94 ppm , p = 0.04 ) . Methane producers ( defined as those with baseline fasting breath methane level > 5 ppm ) were more frequent among subjects with diverticulosis compared to those without diverticulosis ( 50.9 vs. 34 % , p = 0.0025 ) . When adjusted for confounders , breath methane levels and age were the two independent predictors of diverticulosis on colonoscopy with logistic regression modeling . Conclusions Methanogenesis is associated with the presence of diverticulosis . Further studies are needed to confirm our findings and prospect ively evaluate a possible etiological role of methanogenesis and methanogenic archaea in diverticulosis To examine the association between  dietary fiber  ,  sources of fiber , other nutrients , and the diagnosis of  symptomatic diverticular disease , we analyzed data from a prospect i ve cohort of 47,888 US men . During 4 y of follow-up we documented 385 new cases of symptomatic diverticular disease .  Total dietary fiber intake  was inversely associated with the risk of diverticular disease after adjustment for age , energy-adjusted total fat intake , and physical activity [ relative risk ( RR ) 0.58 ; 95 % CI 0.41 , 0.83 ; P for trend = 0.01 for men in the highest as compared with the lowest quintile of dietary fiber ] . This inverse association was primarily due to fruit and vegetable fiber . For men on a high-total-fat , low-fiber diet , the RR was 2.35 ( 95 % CI 1.38 , 3.98 ) compared with those on a low-total-fat , high-fiber diet , and for men on a high-red-meat , low-fiber diet the RR was 3.32 ( 95 % CI 1.46 , 7.53 ) compared with those on a low-red-meat , high-fiber diet . These prospect i ve data support the hypothesis that a diet low in  total dietary fiber  increases the incidence of symptomatic diverticular disease . They also provide evidence that the combination of high intake of total fat or red meat and a diet low in total dietary fiber particularly augments the risk CONTEXT Colonization of the gastrointestinal tract with methanogenic archaea ( methanogens ) significantly affects host metabolism and weight gain in animal models , and breath methane is associated with a greater body mass index ( BMI ) among obese human subjects . OBJECTIVE The objective of the study was to characterize the relationship between methane and hydrogen on breath test ( as a surrogate for colonization with the hydrogen requiring methanogen , Methanobrevibacter smithii ) , body weight , and percent body fat in a general population cohort . DESIGN AND SUBJECTS This was a prospect i ve study ( n = 792 ) of consecutive subjects presenting for breath testing .  SETTING The study was conducted at a tertiary care center . OUTCOME MEASUREMENTS BMI and percent body fat were measured . RESULTS Subjects were classified into 4 groups based on breath testing : normal ( N ) ( methane <3 ppm and hydrogen < 20 ppm at or before 90 minutes ) ; hydrogen positive only ( H+ ) [ methane <3 ppm and hydrogen ≥20 ppm ) ; methane positive only ( M+ ) ( methane ≥3 ppm and hydrogen < 20 ppm ) , or methane and hydrogen positive ( M+/H+ ) ( methane ≥3 ppm and hydrogen ≥20 ppm ] . There were significant differences in age but not in gender across the groups . After controlling for age as a confounding variable , M+/H+ subjects had significantly higher BMI than other groups ( N : 24.1 ± 5.2 kg/m(2 ) ; H+ : 24.2 ± 4.5 kg/m(2 ) ; M+ : 24.0 ± 3.75 kg/m(2 ) ; M+/H+ : 26.5 ± 7.1 kg/m(2 ) , P < .02 ) and also had significantly higher percent body fat ( N : 28.3 ± 10.0 % ; H+ : 27.5 ± 9.0 % ; M+ : 28.0 ± 8.9 % ; M+/H+ ; 34.1 ± 10.9 % , P < .001 ) . CONCLUSIONS The presence of both methane and hydrogen on breath testing is associated with increased BMI and percent body  fat in humans . We hypothesize that this is due to colonization with the hydrogen-requiring M smithii , which affects nutrient availability for the host and may contribute to weight gain Background / Aims The prevalence of colonic diverticulosis has been reported to be lower in Korea than in Western countries . This disease also shows markedly different characteristics in the Korean population . We describe herein a prospect i ve investigation , based on colonoscopic examination , of the prevalence , clinical characteristics , and factors associated with colonic diverticulosis in Korea . Methods The prevalence of colonic diverticulosis has been reported to be lower in Korea than in Western countries . This disease also shows markedly different characteristics in the Korean population . We describe herein a prospect i ve investigation , based on colonoscopic examination , of the prevalence , clinical characteristics , and factors associated with colonic diverticulosis in Korea . Results The overall prevalence of colonic diverticulosis was 12.1 % ( 103 / 848 ) . The right side of the colon was involved in 84.5 % of patients ( 87 / 103 ) ; patients with right side diverticula were , on average , younger than those with left side diverticulosis ( p = 0.014 ) . Multiple diverticula were observed in 60.2 % ( 62 / 103 ) of patients . Age greater than 60 years , a high-fat diet , and alcohol consumption were significantly associated with the presence of colonic diverticulosis ( p < 0.05 ) . Conclusions The prevalence of colonic diverticulosis in Korea is increasing and is most commonly located in the right side of the colon . Further , old age and diet may affect the risk of development of this disease BACKGROUND Obesity is an epidemic that affects 1 in 3 individuals in the United States , and recent evidence suggests that enteric microbiota may play a significant role in the development of obesity . This study evaluated the association between methanogenic archaea and obesity in human subjects . METHODS Subjects with a body mass index ( BMI ) of 30 kg/m² or higher were prospect ively recruited from the weight loss program of a tertiary care medical center . Subjects who met the study 's inclusion criteria were asked to complete a question naire that included a series of visual analogue scores for bowel symptom severities . Subjects then provided a single end-expiratory breath sample to quantitate methane levels . Bivariate and multivariate analyses were used to determine associations with BMI . RESULTS A total of 58 patients qualified for enrollment . Twenty percent of patients ( n = 12 ) had breath test results that were positive for methane ( > 3 parts per million [ ppm ] ) , with a mean breath methane concentration of 12.2±3.1 ppm . BMI was significantly higher in methane-positive subjects ( 45.2±2.3 kg/m² ) than in methane-negative subjects ( 38.5±0.8 kg/m² ; P=.001 ) . Methane-positive subjects also had a greater severity of constipation than methane-negative subjects ( 21.3±6.4 vs 9.5±2.4 ; P=.043 ) . Multiple regression analysis illustrated a significant association between BMI and methane , constipation , and antidepressant use . However , methane remained an independent predictor of elevated BMI when controlling for antidepressant use ( P<.001 ) and when controlling for both constipation and antidepressant use ( 6.55 kg/m² greater BMI ; P=.003 ) . CONCLUSION This is the first human study to demonstrate that a higher concentration of methane detected by breath testing is a predictor of significantly greater obesity in overweight subjects The relationship between physical activity and risk of symptomatic diverticular disease  has not been investigated directly . This association was examined in a prospect i ve cohort of 47,678 American men , 40 to 75 years of age , and free of diagnosed diverticular disease , colon or rectal polyp , ulcerative colitis , and cancer before 1988 . During four years of follow up , 382 newly diagnosed cases of symptomatic diverticular disease were documented . After adjustment for age , energy adjusted dietary fibre , and energy adjusted total fat , overall physical activity  was inversely associated with the risk of symptomatic diverticular disease ( for highest versus lowest extremes , relative risk ( RR ) = 0.63 ( 95 % confidence interval ( CI ) 0.45 , 0.88 ) . Most of the inverse association was attributable to vigorous activity , for extreme categories RR = 0.60 ( 95 % CI 0.41 , 0.87 ) . For activity that was not vigorous the RR was 0.93 ( 95 % CI 0.67 , 1.69 ) . Several specific activities were inversely associated with the risk of diverticular disease , but jogging and running combined was the only individual activity that was statistically significant ( p for trend = 0.03 ) . For men in the lowest quintile for dietary fibre intake and total physical activity ( compared with those in the opposite extreme ) , the RR was 2.56 ( 95 % CI 1.36 , 4.82 ) . Physical activity , along with a high fibre diet , may be an important factor in the prevention of symptomatic diverticular disease The presence of methane on lactulose breath test among irritable bowel syndrome ( IBS ) subjects is highly associated with the constipation-predominant form . Therefore , we set out to determine whether methane gas can alter small intestinal motor function .  In dogs , small intestinal fistulae were created to permit measurement of intestinal transit . Using a radiolabel , we evaluated transit during infusion of room air and subsequently methane . In this model , small intestinal infusion of methane produced a slowing of transit in all dogs by an average of 59 % . In a second experiment , guinea pig ileum was pinned into an organ bath for the study of contractile activity in response to brush strokes applied to the mucosa . The force of contraction was measured both orad and aborad to the stimulus . The experiment was repeated while the bath was gassed with methane .  Contractile activities orad and aborad to the stimulus were significantly augmented by methane compared with room air ( P < 0.05 ) . In a third experiment , humans with IBS who had undergone a small bowel motility study were compared such that subjects who produced methane on lactulose breath test were compared with those producing hydrogen . The motility index was significantly higher in methane-producing IBS patients ( 1,851 + /- 861 ) compared with hydrogen producers ( 1,199 + /- 301 ) ( P < 0.05 ) . Therefore , methane , a gaseous by-product of intestinal bacteria , slows small intestinal transit and appears to do so by augmenting small bowel contractile activity Goals : To investigate whether visceral obesity measured by computed tomography ( CT ) is a risk factor for colonic diverticulosis . Background : The association between colonoscopy-proven diverticulosis and visceral obesity has not been studied . Study : A cohort of 1445 participants ( 1117 nondiverticulosis and 328 diverticulosis ) undergoing colonoscopy and CT was prospect ively analyzed . Diverticulosis was diagnosed by high-resolution colonoscopy . The associations between body mass index ( BMI ) , visceral adipose tissue ( VAT ) area , subcutaneous adipose tissue ( SAT ) area , and diverticulosis were estimated using odds ratios ( ORs ) adjusted for age , sex , alcohol , smoking , medications , and comorbidities . Results : In multivariate analysis , diverticulosis was significantly associated with VAT area and SAT area for both categorical data and trend ( P for trend < 0.001 ) , but not BMI . Diverticulosis had a positive association with VAT area and SAT area for both categorical data and trend ( P for trend < 0.001 ) in men , but none of these associations were noted in women . In the sub analysis of normal-weight patients ( BMI < 25 ) , diverticulosis was independently associated with VAT area and SAT area ( P for trend < 0.001 ) . The adjusted ORs for VAT area ≥100 
    Output:
    
: A significant association between colonic diverticulosis and obesity was shown in this study .