SIMPLER: the Swedish infrastructure for medical population-based life-course and environmental research.

The Swedish Infrastructure for Medical Population-based Life-course and Environmental Research (SIMPLER) is a national research infrastructure that provides longitudinal data and biological samples to investigate how dietary, lifestyle, environmental, and genetic factors influence health and disease across the life course. SIMPLER integrates two population-based prospective cohorts: the Swedish Mammography Cohort and the Cohort of Swedish Men. Baseline data were collected between 1987 and 1990 among 61,433 women and in 1997 among 45,906 men residing in central Sweden. Participants have completed repeated questionnaires on diet, lifestyle, and health approximately every ten years, complemented by linkage to national health registers providing information on diagnoses, mortality, prescribed medications, and socioeconomic status. Two comprehensive subcohorts nested within the cohorts (n = 8046 women, n = 4773 men) provide data from detailed health examinations, questionnaires, and repeated collection of blood, saliva, urine, stool, and adipose tissue biopsy samples. Multi-omics data are available for approximately 12,800 participants, and genomic data for about 51,000 individuals. By integrating long-term questionnaire data, register linkages, and extensive biological sampling, SIMPLER supports research on disease prevention, biomarker discovery, and precision health strategies.