In this study, Dennis Klose and colleagues investigated plasma metabolite levels over time. And they studied how these levels are influenced by demographic factors, somatic health indicators, lifestyle behaviours, psychosocial factors and mental health.

The study
Blood samples from 1902 adults in the Netherlands were measured in the NESDA study at baseline and at six-year follow-up, quantifying 680 plasma metabolites. Rather than analysing all metabolites separately, they were summarized into five metabolome principal components, each representing a specific biochemical profile. Eighteen personal characteristics from baseline were then tested against these components: demographics, psychosocial environment, lifestyle, somatic health, and mental health, to assess their association with metabolic differences between people at baseline and for within-person changes over six years.

Results
Demographic factors (sex, age), somatic health indicators (BMI, medication use), and lifestyle behaviours (smoking, alcohol intake) demonstrated the strongest associations both cross-sectionally and longitudinally. Psychosocial factors and mental health, while showing some statistically significant associations, contributed comparatively modest explained variance.

Further, metabolite levels showed moderate intrapersonal correlation between the two timepoints, meaning that plasma metabolite levels stayed mostly stable over six years within study participants.

Future studies
Future longitudinal metabolomic studies may benefit from extending covariate adjustment beyond the conventional set of age, sex, BMI, medication, and smoking. Several underexplored influences, including urbanisation, work stress, daily hassles, and leisure activity, appear to associate with the plasma metabolome and may help prioritise future intervention studies to improve metabolic health.