DO-HEALTH is a multi-center clinical trial among 2157 community-dwelling European men and women age 70 and older. The 2x2x2 randomized-control factorial design trial tested the individual and additive benefit, as well as the cost-effectiveness, of 3 interventions: vitamin D 2000 IU/day, omega-3 fatty acids 1000 mg/day (EPA + DHA, ratio 1:2), and a 30-minute 3 times/week home exercise (strength versus flexibility). Each treatment tested has shown considerable prior promise from mechanistic studies, small clinical trials, or large cohort studies, in the prevention of common age-related chronic diseases, but definitive data are missing. DO-HEALTH will test these interventions in relation to 6 primary endpoints (systolic and diastolic blood pressure, non-vertebral fractures, Short Physical Performance Battery score, the Montreal Cognitive Assessment, and risk of infections), plus several secondary endpoints explored in ancillary studies (i.e. rate of any falls and injurious falls, joint pain, oral health, quality of life, and incident frailty). As the 3 interventions have distinct mechanisms of action for each of the 6 primary endpoints, a maximum benefit is expected for their additive benefit as a "multi-modal" intervention. The trial duration is 3 years with in-person contacts with all participants at 4 clinical visits and by quarterly phone calls. Baseline and follow-up blood samples were collected in all participants to measure changes in 25-hydroxyvitamin D and poly-unsaturated fatty acid concentrations. Our objective was to test interventions that are expected to promote healthy aging and longer life expectancy and that can be easily and safely implemented by older community-dwelling adults.