DO-HEALTH has been designed as a complementary trial to the NIH-sponsored VITAL trial for 2 of the 3 interventions tested in DO-HEALTH (vitamin D and omega-3). Dr. JoAnn Manson, PI of VITAL and advisor to DO-HEALTH, agreed to collaborate across both studies to enhance their individual value and compare the effects of the individual treatments in the US and Europe. For this, endpoints will be assessed consistently between the two trials for a direct comparison of effects (pooled analysis). DO-HEALTH / VITAL will collaborate to exploit the available data from both studies jointly after the main results have been analyzed for both trials separately. This will further enhance the impact of DO-HEALTH at the public health and global level.