AbstractObjectiveTo explore the relationship between industry sponsorship of Ca supplementation studies in healthy children and study outcomes.DesignAn electronic search for published randomized controlled trials (RCT) was conducted. We collected data on study design features aimed at reducing bias, statistical significance of results, authors’ conclusions and financial sponsorship of study. We used Fischer’s exact test to examine associations between sponsorship and study results and conclusions.SubjectsHealthy children between the ages of 9 and 18 years.ResultsNineteen trials met our inclusion criteria. Seventeen out of nineteen studies reported a statistically significant improvement of supplementation on bone mineral density. Subjects in eight of the seventeen studies had a baseline daily Ca intake of 800–1300 mg. There was no significant association between study design features and the results or conclusions of the studies. Three studies received government funding, two of which (66·7 %) concluded in favour of additional supplementation. Sixteen studies were either industry-funded or had mixed industry funding, thirteen (81·3 %) of which had a conclusion supporting Ca supplementation in children. There was no significant association between study sponsorship and authors’ conclusions.ConclusionsThe majority of RCT assessing the effects of Ca supplementation in healthy children are industry-funded and support Ca supplementation. The clinical significance of the outcomes measured in Ca supplementation studies should be considered when examining associations between study design and results. Further non-industry funded research is needed to thoroughly assess the impact of funding on authors’ conclusions in nutrition research.