Associations between outdoor temperature and bright sunlight with metabolites in two population-based European cohorts

Background and aims Outdoor temperature and bright sunlight may directly and/or indirectly modulate systemic metabolism. We assessed the associations between outdoor temperature and bright sunlight duration with metabolomics. Methods and results Cross-sectional analyses were undertaken in non-diabetic individuals from the Oxford BioBank (OBB; N = 6368; mean age 47.0 years, males 44%) and the Netherlands Epidemiology of Obesity (NEO; N = 5916; mean age 55.6 years, males 43%) study. Data on mean outdoor bright sunlight and temperature were collected from local weather stations in the week prior to blood sampling. Fasting serum levels of 148 metabolites, including 14 lipoprotein subclasses, were measured using NMR spectroscopy. Linear regression analyses were performed to assess the associations between mean outdoor temperature and bright sunlight duration with metabolomics adjusted for age, sex, body mass index, season and either outdoor temperature or bright sunlight. A higher mean outdoor temperature was associated with increased serum concentrations of lipoprotein (sub)particles (β (SE) = 0.064 (0.018) SD per 5 °C, p = 5.03e−4) and certain amino acids such as phenylalanine (0.066 (0.016) SD, p = 6.44e−05) and leucine (0.111 (0.018) SD, p = 1.25e−09). In contrast, longer duration of bright sunlight was specifically associated with lower concentrations of very low-density lipoprotein (sub)particles (e.g., VLDL cholesterol (−0.024 (0.005) SD per 1-h bright sunlight, p = 8.06e−6)). The direction of effects was generally consistent between the OBB and NEO, although effect sizes were generally larger in the OBB. Conclusions Increased bright sunlight duration is associated with an improved metabolic profile whilst higher outdoor temperature may adversely impact cardiometabolic health.