GrassrootsHealth is a US non-profit research institute focused on bridging the gap between vitamin D research and public-health practice. Its flagship project, the D*action study, collects blood-test data from thousands of participants to map vitamin D status against health outcomes — a citizen-science approach that runs in parallel to traditional trials.
How the data is collected
Participants submit dried-blood-spot tests at intervals and answer surveys on health, supplementation, and lifestyle. The pooled data set is then used to publish on questions like the relationship between serum 25(OH)D levels and risks of specific conditions, optimal supplementation ranges, and how status varies by latitude and season.
Where it sits in the debate
GrassrootsHealth advocates higher target vitamin D blood levels than most government guidelines — a position aligned with some researchers and contested by others. Coverage on bavida treats the organisation's data as useful raw material, while noting that its conclusions sit on the more aggressive end of the supplementation spectrum.