Study: Vitamin D2 lowers circulating D3 levels

A University of Surrey–led meta-analysis of 11 randomized controlled trials (655 adults), published in Nutrition Reviews, found that taking vitamin D2 supplements reduces circulating vitamin D3 levels compared with those not taking D2. Researchers say the finding suggests vitamin D3 may be more beneficial for most individuals, while calling for further research on differential effects and implications for supplementation and fortification.