Lifestyle Risk Factors for Serrated Colorectal Polyps: A Systematic Review and Meta-analysis.
Plain language summary
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.
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.
Nonnutritive sweeteners and cardiometabolic health: a systematic review and meta-analysis of randomized controlled trials and prospective cohort studies.
CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne. 2017;189(28):E929-E939
Plain language summary
Obesity is a major public health challenge that contributes to type 2 diabetes and cardiovascular disease. Evidence that sugar consumption is fuelling this epidemic has stimulated the increasing popularity of non-nutritive sweeteners including aspartame, sucralose and stevioside. The aim of this study was to synthesize evidence of whether routine consumption of non-nutritive sweeteners by adults and adolescents is associated with adverse long-term cardiometabolic effects. This study is a systemic review and meta-analysis of randomised controlled trials and prospective cohort studies. It includes 37 studies involving a total of 406910 individuals. The study shows that small RCTs with short follow-up (median 6 months) suggest that consumption of non-nutritive sweeteners is not consistently associated with decreases in body weight, BMI or waist circumference. However, in larger prospective cohort studies with longer follow-up periods (median 10 years), intake of non-nutritive sweeteners is significantly associated with modest long-term increases in each of these measures. Authors conclude that caution in the use of non-nutritive sweeteners is warranted until the long-term risks and benefits of these products are fully characterised.
BACKGROUND Nonnutritive sweeteners, such as aspartame, sucralose and stevioside, are widely consumed, yet their long-term health impact is uncertain. We synthesized evidence from prospective studies to determine whether routine consumption of non-nutritive sweeteners was associated with long-term adverse cardiometabolic effects. METHODS We searched MEDLINE, Embase and Cochrane Library (inception to January 2016) for randomized controlled trials (RCTs) that evaluated interventions for nonnutritive sweeteners and prospective cohort studies that reported on consumption of non-nutritive sweeteners among adults and adolescents. The primary outcome was body mass index (BMI). Secondary outcomes included weight, obesity and other cardiometabolic end points. RESULTS From 11 774 citations, we included 7 trials (1003 participants; median follow-up 6 mo) and 30 cohort studies (405 907 participants; median follow-up 10 yr). In the included RCTs, nonnutritive sweeteners had no significant effect on BMI (mean difference -0.37 kg/m ; 95% confidence interval [CI] -1.10 to 0.36; 9%; 242 participants). In the included cohort studies, consumption of nonnutritive sweeteners was associated with a modest increase in BMI (mean correlation 0.05, 95% CI 0.03 to 0.06; 0%; 21 256 participants). Data from RCTs showed no consistent effects of nonnutritive sweeteners on other measures of body composition and reported no further secondary outcomes. In the cohort studies, consumption of nonnutritive sweeteners was associated with increases in weight and waist circumference, and higher incidence of obesity, hypertension, metabolic syndrome, type 2 diabetes and cardiovascular events. Publication bias was indicated for studies with diabetes as an outcome. INTERPRETATION Evidence from RCTs does not clearly support the intended benefits of nonnutritive sweeteners for weight management, and observational data suggest that routine intake of nonnutritive sweeteners may be associated with increased BMI and cardiometabolic risk. Further research is needed to fully characterize the long-term risks and benefits of nonnutritive sweeteners. PROSPERO-CRD42015019749.
Dietary acrylamide and cancer risk: an updated meta-analysis.
International journal of cancer. 2015;136(12):2912-22
Plain language summary
Acrylamide is formed in a variety of foods, and some evidence suggests it may cause cancer. The aim of this study was to update their quantitative meta-analysis on dietary acrylamide intake and cancer risk. The study is a meta-analysis based on systemic-literature focusing on the estimate of total dietary acrylamide. A total of 32 publications were reviewed. Results indicate that there is a lack of association between dietary acrylamide and most cancer sites. However, there is a potential small increase in the risk between high levels of acrylamide intake and kidney, endometrial and ovarian cancer in non-smoking women. Authors conclude that dietary acrylamide is not related to the risk of most common cancers.
The debate on the potential carcinogenic effect of dietary acrylamide is open. In consideration of the recent findings from large prospective investigations, we conducted an updated meta-analysis on acrylamide intake and the risk of cancer at several sites. Up to July 2014, we identified 32 publications. We performed meta-analyses to calculate the summary relative risk (RR) of each cancer site for the highest versus lowest level of intake and for an increment of 10 µg/day of dietary acrylamide, through fixed-effects or random-effects models, depending on the heterogeneity test. Fourteen cancer sites could be examined. No meaningful associations were found for most cancers considered. The summary RRs for high versus low acrylamide intake were 0.87 for oral and pharyngeal, 1.14 for esophageal, 1.03 for stomach, 0.94 for colorectal, 0.93 for pancreatic, 1.10 for laryngeal, 0.88 for lung, 0.96 for breast, 1.06 for endometrial, 1.12 for ovarian, 1.00 for prostate, 0.93 for bladder and 1.13 for lymphoid malignancies. The RR was of borderline significance only for kidney cancer (RR = 1.20; 95% confidence interval, CI, 1.00-1.45). All the corresponding continuous estimates ranged between 0.95 and 1.03, and none of them was significant. Among never-smokers, borderline associations with dietary acrylamide emerged for endometrial (RR = 1.23; 95% CI, 1.00-1.51) and ovarian (RR = 1.39; 95% CI, 0.97-2.00) cancers. This systematic review and meta-analysis of epidemiological studies indicates that dietary acrylamide is not related to the risk of most common cancers. A modest association for kidney cancer, and for endometrial and ovarian cancers in never smokers only, cannot be excluded.