Whether the risk of gastric cancer varies by the types of meat consumption still remains disputable. The purpose of this meta-analysis was to identify the exact associations that red, processed, and white meat have with gastric cancer. We searched relevant studies in Medline, EMBASE, and the Cochrane Library before November 2018, including cohort and case-control studies. We used random-effect models to estimate the adjusted relative risk (RR), and Egger’s tests to evaluate publication bias. Through stepwise screening, 43 studies were included in this analysis (11 cohort studies and 32 case-control studies with 16,572 cases). In a meta-analysis for the highest versus lowest categories of meat consumption, both red (RR: 1.41, 95% confidence interval (CI): 1.21–1.66) and processed (RR: 1.57, 95% CI: 1.37–1.81) meat consumption were positively associated with gastric cancer risk, while white meat consumption was negatively associated with gastric cancer risk (RR: 0.80, 95% CI: 0.69–0.92). In a dose–response meta-analysis, the RRs of gastric cancer were 1.26 (95% CI: 1.11–1.42) for every 100 g/day increment in red meat consumption, 1.72 (95% CI: 1.36–2.18) for every 50 g/day increment in processed meat consumption, and 0.86 (95% CI: 0.64–1.15) for every 100 g/day increment in white meat consumption. The increase of white meat consumption may reduce the risk of gastric cancer, while red or processed meat may increase the risk of gastric cancer. Further studies are required to identify these associations, especially between white meat and gastric cancer.

Little is known about the trade-off between the health benefits of physical activity (PA) and the potential harmful effects of increased exposure to air pollution during outdoor PA. We examined the association of the combined effects of air pollution and changes in PA with cardiovascular disease (CVD) in young adults. This nationwide cohort study included 1 469 972 young adults aged 20–39 years. Air pollution exposure was estimated by the annual average cumulative level of particulate matter (PM). PA was calculated as minutes of metabolic equivalent tasks per week (MET-min/week) based on two consecutive health examinations from 2009 to 2012. Compared with the participants exposed to low-to-moderate levels of PM2.5 or PM10 who continuously engaged in ≥1000 MET-min/week of PA, those who decreased their PA from ≥1000 MET-min/week to 1–499 MET-min/week [PM10 adjusted hazard ratio (aHR) 1.22; 95% confidence interval (CI) 1.00–1.48] and to 0 MET-min/week (physically inactive; PM10 aHR 1.38; 95% CI 1.07–1.78) had an increased risk of CVD (P for trend <0.01). Among participants exposed to high levels of PM2.5 or PM10, the risk of CVD was elevated with an increase in PA above 1000 MET-min/week. Reducing PA may lead to subsequent elevation of CVD risk in young adults exposed to low-to-moderate levels of PM2.5 or PM10, whereas a large increase in PA in a high-pollution environment may adversely affect cardiovascular health. Combined effects of air pollution and changes in physical activity with cardiovascular disease in young adults.

The primary objective of this study was to investigate adverse effects of ambient particulate matter of various sizes on the incidence of the prevalent autoimmune rheumatic diseases (AIRDs): RA, AS and SLE. We investigated 230 034 participants in three metropolitan cities of South Korea from the National Health Insurance Service–National Sample Cohort (NHIS-NSC). Starting from January 2010, subjects were followed up until the first event of prevalent AIRDs, death, or December 2013. The 2008–2009 respective averages of particulate matter_2.5 (<2.5 μm) and particulate matter_coarse (2.5 μm to 10 μm) were linked with participants’ administrative district codes. Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox regression analysis in one- and two-pollutant models. Adjusted for age, sex, region, and household income, in the two-pollutant model, RA incidence was positively associated with the 10 μg/m³ increment of particulate matter_2.5 (aHR = 1.74, 95% CI: 1.06, 2.86), but not with particulate matter_coarse (aHR = 1.27, 95% CI: 0.87, 1.85). In the one-pollutant model, the elevated incidence rate of RA was slightly attenuated (particulate matter_2.5 aHR = 1.61, 95% CI: 0.99, 2.61; particulate matter_coarse aHR = 1.13, 95% CI: 0.80, 1.61), with marginal statistical significance for particulate matter_2.5. The RA incidence was also higher in the 4th quartile group of particulate matter_2.5 compared with the first quartile group (aHR = 1.83, 95% CI: 1.07, 3.11). Adverse effects from particulate matter were not found for AS or SLE in either the one- or two-pollutant models. The important components of particulate matter₁₀ associated with RA incidence were the fine fractions (particulate matter_2.5); no positive association was found between particulate matter and AS or SLE.

(1) Background: There is limited information regarding association between long-term exposure to air pollutants and risk of chronic kidney disease (CKD) (2). Methods: This study acquired data of 164,093 adults aged at least 40 years who were residing in 7 metropolitan cities between 2002 and 2005 from the Korean National Health Insurance Service National Sample Cohort database. CKD risk was evaluated using the multivariate Cox hazards proportional regression. All participants were followed up with until CKD, death, or 31 December 2013, whichever occurred earliest. (3) Results: Among 1,259,461 person-years of follow-up investigation, CKD cases occurred in 1494 participants. Air pollutant exposures including PM₁₀, SO₂, NO₂, CO, and O₃ showed no significant association with incident CKD after adjustments for age, sex, household income, area of residence, and the Charlson comorbidity index. The results were consistent in the sensitivity analyses including first and last year annual exposure analyses as well as latent periods-washed-out analyses. (4) Conclusions: Long-term exposure to air pollution is not likely to increase the risk of CKD.

Physical activity (PA), especially outdoor PA, may have twofold effects on diabetes risk: the health benefits of PA and the potential detrimental effects caused by augmented exposure to air pollution. We examined the association of combined effects of PA and air pollution with diabetes in older adults. The study participants consisted of 1,259,871 older adults aged 58 years or more from the Korean National Health Insurance Service database. The exposure to air pollution was estimated by the average ambient levels of particulate matter (PM) of the participants' residence area. Cox proportional hazards models were used to evaluate the adjusted hazard ratios and 95% confidence intervals of developing diabetes according to the combined effect of moderate to vigorous physical activity (MVPA) and air pollution exposure. Engaging in 5 or more times of MVPA/week was associated with decreased risk of diabetes within groups with both high and low/moderate levels of exposure to PM10 (low/moderate PM10 aHR 0.91, 95% CI 0.89-0.93; high PM10 aHR 0.97, 95% CI 0.94-0.99) or PM2.5 (low/moderate PM2.5 aHR 0.88, 95% CI 0.85-0.90; high PM10 aHR 0.95, 95% CI 0.91-0.99) exposure. The risk-reducing effects upon MVPA tended to be slightly attenuated, which showed the reverse J-shaped association, but still significant, among those who were exposed to a high level of air pollution. The association was consistent among stratified analyses according to the possible confounders. MVPA may be inversely associated with the risk of diabetes development within groups with both high and low/moderate levels of exposure to PM10 or PM2.5 in older adults. Future studies are necessary to validate whether the positive health effects of MVPA outweigh the potential detrimental effects due to augmented exposure to air pollution during MVPA.