Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth

BACKGROUND

While colorectal polyps are not cancerous, some types of polyps, known as adenomas, can develop into colorectal cancer over time. Polyps can often be found and removed by colonoscopy; however, this is an invasive and expensive test. Thus, there is a need for new methods of screening patients at high risk of developing polyps.

AIM

To identify a potential association between colorectal polyps and small intestine bacteria overgrowth (SIBO) or other relevant factors in a patient cohort with lactulose breath test (LBT) results.

METHODS

A total of 382 patients who had received an LBT were classified into polyp and non-polyp groups that were confirmed by colonoscopy and pathology. SIBO was diagnosed by measuring LBT-derived hydrogen (H) and methane (M) levels according to 2017 North American Consensus recommendations. Logistic regression was used to assess the ability of LBT to predict colorectal polyps. Intestinal barrier function damage (IBFD) was determined by blood assays.

RESULTS

H and M levels revealed that the prevalence of SIBO was significantly higher in the polyp group than in the non-polyp group (41% vs 23%, P < 0.01; 71% vs 59%, P < 0.05, respectively). Within 90 min of lactulose ingestion, the peak H values in the adenomatous and inflammatory/hyperplastic polyp patients were significantly higher than those in the non-polyp group (P < 0.01, and P = 0.03, respectively). In 227 patients with SIBO defined by combining H and M values, the rate of IBFD determined by blood lipopolysaccharide levels was significantly higher among patients with polyps than those without (15% vs 5%, P < 0.05). In regression analysis with age and gender adjustment, colorectal polyps were most accurately predicted with models using M peak values or combined H and M values limited by North American Consensus recommendations for SIBO. These models had a sensitivity of ≥ 0.67, a specificity of ≥ 0.64, and an accuracy of ≥ 0.66.

CONCLUSION

The current study made key associations among colorectal polyps, SIBO, and IBFD and demonstrated that LBT has moderate potential as an alternative noninvasive screening tool for colorectal polyps.

The Pathogenesis of Nonalcoholic Fatty Liver Disease: Interplay between Diet, Gut Microbiota, and Genetic Background. Gastroenterol Res Pract. 2016;2016:2862173. [PMID: 27247565 PMCID: PMC4876215 DOI: 10.1155/2016/2862173]

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and it comprises a spectrum of hepatic abnormalities from simple hepatic steatosis to steatohepatitis, fibrosis, cirrhosis, and liver cancer. While the pathogenesis of NAFLD remains incompletely understood, a multihit model has been proposed that accommodates causal factors from a variety of sources, including intestinal and adipose proinflammatory stimuli acting on the liver simultaneously. Prior cellular and molecular studies of patient and animal models have characterized several common pathogenic mechanisms of NAFLD, including proinflammation cytokines, lipotoxicity, oxidative stress, and endoplasmic reticulum stress. In recent years, gut microbiota has gained much attention, and dysbiosis is recognized as a crucial factor in NAFLD. Moreover, several genetic variants have been identified through genome-wide association studies, particularly rs738409 (Ile748Met) in PNPLA3 and rs58542926 (Glu167Lys) in TM6SF2, which are critical risk alleles of the disease. Although a high-fat diet and inactive lifestyles are typical risk factors for NAFLD, the interplay between diet, gut microbiota, and genetic background is believed to be more important in the development and progression of NAFLD. This review summarizes the common pathogenic mechanisms, the gut microbiota relevant mechanisms, and the major genetic variants leading to NAFLD and its progression.