Cold exposure, gut microbiota and health implications: A narrative review.

Temperature has been recognized as an important environmental factor affecting the composition and function of gut microbiota (GM). Although research on high-temperature impacts has been well studied, knowledge about the effect of cold exposure on GM remains limited. This narrative review aims to synthesize the latest scientific findings on the impact of cold exposure on mammalian GM, and its potential health implications. Chronic cold exposure could disrupt the α-diversity and the composition of GM in both experimental animals and wild-living hosts. Meanwhile, cold exposure could impact gut microbial metabolites, such as short-chain fatty acids. We also discussed plausible biological pathways and mechanisms by which cold-induced changes may impact host health, including metabolic homeostasis, fitness and thermogenesis, through the microbiota-gut-brain axis. Intriguingly, alterations in GM may provide a tool for favorably modulating the host response to the cold temperature. Finally, current challenges and future perspectives are discussed, emphasizing the need for translational research in humans. GM could be manipulated by utilizing nutritional strategies, such as probiotics and prebiotics, to deal with cold-related health issues and enhance well-being in populations living or working in cold environments.

Associations of PM2.5 composition and green space with metabolic syndrome in a Chinese essential hypertensive population.

BACKGROUND: Metabolic syndrome (MetS) has emerged as a significant global public health concern. While environmental factors, including PM2.5, have been identified as important risk factors for MetS in the general population, limited studies have investigated their impact on individuals with essential hypertension. Therefore, our study aims to explore the relationship between PM2.5 composition, green space, and their combined effects on MetS among a Chinese essential hypertensive population. METHOD: A total of 20,131 participants diagnosed with essential hypertension from 10 provinces in China were included in this study. Individual level exposure to various environmental factors (including PM2.5, PM2.5 composition, green space and temperature) were evaluated using spatiotemporal models based on satellites data. Participants were defined as MetS according to the definition issued by the International Diabetes Federation. Generalized additive mixed models were used to analyze the individual air pollutants, green space and their interaction on MetS. RESULT: The prevalence of MetS in this population was 44.33%. The adjusted odd ratio (OR) of MetS, with each one unit increase in SO42-, BC and NO3- were 1.077 (1.049, 1.106), 1.126 (1.077, 1.177) and 0.977 (0.958, 0.996) respectively. Additionally, each unit increase of the Normalized Difference Vegetation Index (NDVI) was associated with a decreased risk of MetS (OR: 0.988, 95% CI: 0.984-0.993). In particular, green space was found to mitigate the adverse impacts of PM2.5 on MetS (OR: 0.988, 95% CI: 0.984-0.993). CONCLUSION: Our results suggested that there was a positive association between PM2.5 and its composition (SO42-, BC) with MetS in the essential hypertensive population, while green space might play a protective role. Moreover, green space could effectively weaken the positive relationship between air pollutants and MetS, especially in males and participants younger than 60 years old.

Association between salt sensitivity of blood pressure and the risk of hypertension in a Chinese Tibetan population.

Epidemiological studies have confirmed salt sensitivity as a crucial risk factor for the development of hypertension. However, few studies have investigated the association between salt sensitivity of blood pressure (SSBP) and hypertension in Chinese Tibetan population. Therefore, we conducted a cross-sectional study based on a Tibetan population to evaluate the association between SSBP and the risk of hypertension. Seven hundred and eighty-four participants with hypertension and 645 participants without hypertension were included from five villages in Tibetan Autonomous Region of Gannan during 2013-2014. The assessment of salt sensitivity (SS) and non-salt sensitivity (NSS) was performed according to mean arterial pressure (MAP) changes by the modified Sullivan's acute oral saline load and diuresis shrinkage test (MSAOSL-DST). Logistic regression models and restricted cubic models were used to examine the association between SSBP and hypertension. There were 554 (70.5%) salt-sensitive participants with hypertension and 412 (63.9%) salt-sensitive participants without hypertension in this study. Compared with individuals with NSS, individuals with SS had a significantly increased risk of hypertension, and the multiple-adjusted odds ratios were 2.582 with 95% confidence interval of 1.357-4.912. Furthermore, a significant linear trend was found between MAP changes and hypertension. Subgroup analyses showed significant and stronger associations between SSBP and the risk of hypertension in the older (age ≥ 55 years old), males and participants who took exercise less than 1 time per week. Our results suggest that SS is associated with an increased risk of hypertension in Tibetan population, indicating a need for clinicians dealing with SSBP to decrease the risk of hypertension.