Summer Temperature Exposure and Blood Metabolomics in Young Adults: A Cross-Sectional Study in Shandong, China

Epidemiological evidence of the blood metabolic mechanisms through which summer temperatures affect human health is scarce, despite the well-established risks and increasing severity under a warming climate. Based on the Chinese Undergraduates Cohort (CUC), we aim to explore the association between summer temperature exposure and blood metabolomics in young adults. Plasma samples were tested with an untargeted metabolomic analysis. Meteorological data was collected from China Meteorological Data Sharing Service System. The three consecutive months with the highest monthly average temperatures of the whole year were defined as summer. One-way analysis of variance (ANOVA) and the multiple linear regression model were used to assess the effects of summer mean temperature exposure on blood metabolomics, followed by stratified analysis by sex. A total of 1,930 participants, with a mean age of 18.18 ± 0.65 years, were included in this study. The summer mean temperature was 26.03 ± 1.70 °C. Metabolomic analysis identified 54 altered metabolites related to summer mean temperature, of which 7 altered metabolites were enriched in 4 significant metabolic pathways (p < 0.05), which were mainly involved in amino acid and peptide compound metabolism. Stratified analysis results showed that in addition to amino acid metabolism, summer mean temperature exposure also disrupted vitamin metabolism in females. Summer mean temperature could possibly be associated with altered metabolic pathways such as amino acid metabolism, causing inflammation and oxidative stress damage. Females could be more susceptible to summer temperature in terms of disrupted vitamin metabolism.