1.
Association between physical activity and changes in intestinal microbiota composition: A systematic review.
Aya, V, Flórez, A, Perez, L, Ramírez, JD
PloS one. 2021;16(2):e0247039
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The human gut flora or microbiota is made up of many different microorganisms, including bacteria, fungi, and viruses. Researchers still find it difficult to clearly define what constitutes a healthy gut flora. This is made more challenging by the fact that the array of microorganisms in the gut are influenced by multiple internal and external factors. Such as diet, sleep, circadian rhythm, age, and physical activity, and they also change with disease. This review sought to gather the current evidence on how physical activity (external factor) impacts the microbial make-up of the gut in healthy humans and the conferred metabolic benefits on the human host. The review included 17 studies with the findings from athletes and exercise intervention programs. Whereby some research demonstrates a consistent beneficial relationship between a favourable microbiota composition and exercise, the authors felt unable to draw a firm conclusion due to the complexity of the microbial system and other influencing factors. The authors called for further, larger scaled studies, that should distinguish between different types of exercise (i.e. endurance and high-intensity training) and age groups, as well as incorporating more information on the subject's diet and lifestyle factors. Of clinical relevance could be the potential of physical activity as a modulator gut microbiome composition.
Abstract
INTRODUCTION The intestinal microbiota comprises bacteria, fungi, archaea, protists, helminths and viruses that symbiotically inhabit the digestive system. To date, research has provided limited data on the possible association between an active lifestyle and a healthy composition of human microbiota. This review was aimed to summarize the results of human studies comparing the microbiome of healthy individuals with different physical activity amounts. METHODS We searched Medline/Ovid, NIH/PubMed, and Academic Search Complete between August-October 2020. Inclusion criteria comprised: (a) cross-sectional studies focused on comparing gut microbiome among subjects with different physical activity levels; (b) studies describing human gut microbiome responses to any type of exercise stimulus; (c) studies containing healthy adult women and men. We excluded studies containing diet modifications, probiotic or prebiotic consumption, as well as studies focused on diabetes, hypertension, cancer, hormonal dysfunction. Methodological quality and risk of bias for each study were assessed using the Risk Of Bias In Non-randomized Studies-of Interventions tool. The results from cross-sectional and longitudinal studies are shown independently. RESULTS A total of 17 articles were eligible for inclusion: ten cross-sectional and seven longitudinal studies. Main outcomes vary significantly according to physical activity amounts in longitudinal studies. We identified discrete changes in diversity indexes and relative abundance of certain bacteria in active people. CONCLUSION As literature in this field is rapidly growing, it is important that studies incorporate diverse methods to evaluate other aspects related to active lifestyles such as sleep and dietary patterns. Exploration of other groups such as viruses, archaea and parasites may lead to a better understanding of gut microbiota adaptation to physical activity and sports and its potentially beneficial effects on host metabolism and endurance.
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Lifestyle Risk Factors for Serrated Colorectal Polyps: A Systematic Review and Meta-analysis.
Bailie, L, Loughrey, MB, Coleman, HG
Gastroenterology. 2017;152(1):92-104
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Colorectal cancer (CRC) is a heterogeneous disease thought to result from the accumulation of various aberrant mutations in the cells lining the colorectal mucosa. The aim of this systematic review and meta-analysis was to evaluate modifiable and lifestyle factors and the risk of serrated polyps (a type of growth that stick out from the surface of the colon or rectum) of the colorectum. A search of 3 databases yielded a potential 2446 studies for inclusion, from which 43 remained for systematic review. Results indicate that smoking, alcohol consumption, body fatness, dietary fat and meat consumption increased the risk of developing serrated polyps. Whereas, nonsteroidal anti-inflammatory drugs, aspirin and dietary folate decreased this risk. Authors conclude that their findings strengthen public health messages promoting awareness and change in order to reduce the risk of these precancerous lesions and consequently CRC.
Abstract
BACKGROUND & AIMS Certain subsets of colorectal serrated polyps (SP) have malignant potential. We performed a systematic review and meta-analysis to investigate the association between modifiable lifestyle factors and risk for SPs. METHODS We conducted a systematic search of Medline, Embase, and Web of Science for observational or interventional studies that contained the terms risk or risk factor, and serrated or hyperplastic, and polyps or adenomas, and colorectal (or synonymous terms), published by March 2016. Titles and abstracts of identified articles were independently reviewed by at least 2 reviewers. Adjusted relative risk (RR) and 95% confidence interval (CI) were combined using random effects meta-analyses to assess the risk of SP, when possible. RESULTS We identified 43 studies of SP risk associated with 7 different lifestyle factors: smoking, alcohol, body fatness, diet, physical activity, medication, and hormone-replacement therapy. When we compared the highest and lowest categories of exposure, factors we found to significantly increase risk for SP included tobacco smoking (RR, 2.47; 95% CI, 2.12-2.87), alcohol intake (RR, 1.33; 95% CI, 1.17-1.52), body mass index (RR, 1.40; 95% CI, 1.22-1.61), and high intake of fat or meat. Direct associations for smoking and alcohol, but not body fat, tended to be stronger for sessile serrated adenomas/polyps than hyperplastic polyps. In contrast, factors we found to significantly decrease risks for SP included use of nonsteroidal anti-inflammatory drugs (RR, 0.77; 95% CI, 0.65-0.92) or aspirin (RR, 0.81; 95% CI, 0.67-0.99), as well as high intake of folate, calcium, or fiber. No significant associations were detected between SP risk and physical activity or hormone replacement therapy. CONCLUSIONS Several lifestyle factors, most notably smoking and alcohol, are associated with SP risk. These findings enhance our understanding of mechanisms of SP development and indicate that risk of serrated pathway colorectal neoplasms could be reduced with lifestyle changes.