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.

Few previous studies have investigated the association between urban green space and cardiovascular disease (CVD) within Asian populations. We aimed to determine the relationship between amount of green space in the residential environment and CVD within a large general Asian population in this population-based longitudinal study. The study population consisted of 351,409 participants aged over 20 years extracted from the National Health Insurance Service National Sample Cohort. Data on newly-occurred CVD events were collected from hospital admission records for the period 1 January 2006 to 31 December 2013. Cox proportional hazards regression analysis was used for determining the risk of developing CVD according to urban green space coverage (% area), adjusting for a number of relevant confounders. Compared to those within the lowest quartile of green space coverage, those within the highest quartile of urban space had a reduced risk of total CVD (hazard ratio, HR 0.85, 95% confidence interval, CI 0.81-0.89), coronary heart disease (HR 0.83, 95% CI 0.78-0.89), acute myocardial infarction (HR 0.77, 95% CI 0.68-0.88), total stroke (HR 0.87, 95% CI 0.82-0.93) and ischemic stroke (HR 0.86, 95% CI 0.80-0.94), but not hemorrhagic stroke (HR 0.98, 95% CI 0.86-1.12). The risk-reducing effect of green space coverage was preserved after stratification according to sex, household income, and Charlson comorbidity index. Residing in urban regions with greater green space coverage may lead to a reduced risk of CVD. Urban planning intervention policies that increase urban green space coverage could help to reduce the risk of CVD.

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.

Relationship of muscle mass and fat mass with insulin resistance and metabolic syndrome remains uncertain, especially among Asian population. We performed a cross-sectional study with 14,807 adult participants aged between 18 and 65 in the fourth and fifth Korea National Health and Nutrition Examination Survey with Dual Energy X-ray Absorptiometry (DEXA) data to investigate whether muscle mass and fat mass are associated with insulin resistance and metabolic syndrome. DEXA records were used to categorize the participants into four categories (low muscle/low fat, low muscle/high fat, high muscle/ low fat, and high muscle/high fat). Least square means and incidence rate ratios (IRR) were used to assess the associations of muscle mass and fat mass with insulin resistance and metabolic syndrome. After adjustment for potential confounders, high muscle/low fat was associated with significantly lower insulin resistance (P < 0.001) compared to low muscle/low fat. Low muscle/high fat (IRR: 1.90; 95% confidence interval [CI]:1.44–2.50, P < 0.001) and high muscle/high fat (IRR: 2.30; 95% CI:1.76–3.00, P < 0.001) were significantly associated with the prevalence of metabolic syndrome. Our study suggests that protective association of muscle mass with metabolic syndrome is attenuated by high fat mass in Korean adults.

The effect of aspirin on the risk of hepatocellular carcinoma (HCC) remains unclear. We investigated the association between aspirin use and HCC development in a region where viral hepatitis prevails. We conducted a population-based cohort study including a total of 460,755 participants who were tracked to identify incidents of HCC since 2007. The use of drug before the index date was assessed and standardized by the Defined Daily Dose system. We calculated the hazard ratios (HRs) and their 95% confidence intervals (CIs) for the association between aspirin use and HCC occurrence, using Cox proportional hazard regression models. There were 2,336 cases of HCC during the period of 2,965,500 person-years. Overall, aspirin users had a lower HCC risk (HR, 0.87; 95% CI, 0.77–0.98) than non-users in a dose-response manner (P_trend = 0.002). The protective effect of aspirin was amplified when combined with those of non-aspirin non-steroidal anti-inflammatory drugs (HR, 0.65; 95% CI, 0.50–0.85). Subgroup analyses revealed a significant chemopreventive effect of aspirin in individuals who were young, were male, or had viral hepatitis, whereas no protective effect was observed in patients with liver cirrhosis. Our results, suggesting different carcinogenic pathways between viral and non-viral etiologies, may validate the design of future intervention trials of aspirin for HCC prevention in eligible populations.

Little is known about the association of changes in moderate to vigorous physical activity (MVPA) level with cardiovascular disease (CVD), especially in older adults whose ability to engage in frequent MVPA naturally wanes as they age. We aimed to examine the association of changes in MVPA and CVD in older adults. In a nationwide cohort study of older adults aged 60 years or older, we identified more than 1.1 million subjects without previous history of CVD at baseline who underwent two consecutive national health screening from 2009 to 2012. We prospectively assessed the risk of CVD occurred between 2013 and 2016 according to changes in frequency of MVPA by initial MVPA status. Compared to those who were continuously physically inactive, those who increased their frequency of MVPA from physically inactive to 1–2 times per week [0.7/1000 person-years (PY) decrease in incidence rate (IR); adjusted hazard ratio (aHR) 0.95; 95% confidence interval (CI) 0.92–0.99], 3–4 times per week (1.5/1000 PY decrease in IR; aHR 0.89; 95% CI 0.84–0.94), ≥5 times per week (0.4/1000 PY decrease in IR; aHR 0.91; 95% CI 0.85–0.97) had a significantly reduced risk for total CVD (P for trend <0.001). Older adults who became physically inactive from engaging in more than 1–2 times of MVPA per week had a higher CVD risk compared to those who maintained their frequency of MVPA. Among older adults, engaging in higher frequency of MVPA or maintaining MVPA level was associated with reduced risk of CVD.