Across randomized trials, vitamin D2 lined up with lower vitamin D3 in the blood

What the research found

Study (meta-analysis of randomized trials). ScienceDaily carried the University of Surrey account on 8 October 2026. Emily I. G. Brown and colleagues report in Nutrition Reviews (2025; doi 10.1093/nutrit/nuaf166), with the John Innes Centre and the Quadram Institute. The news date is later than that paper. The review covered 20 trials, with 11 in the main meta-analysis. People taking vitamin D2 (ergocalciferol) had lower 25-hydroxyvitamin D3 than people not given D2, by roughly 9 to 18 nanomoles per liter depending on the analysis. D2 still raises 25-hydroxyvitamin D2 and can add to total vitamin D. The release says this is not evidence that D2 removes vitamin D from the body. A separate 2026 review of 26 trials (Nutrition Reviews 2026; 84(3):571; doi 10.1093/nutrit/nuaf102) found D2 lowered parathyroid hormone and slightly raised blood calcium. An earlier gene-activity study from the same university is described as suggesting D3, not D2, lined up with type I interferon signaling. That is not proof that D3 prevents infection. The release does not give one age band or a sex split. Researchers said it is still unknown whether the D3 drop changes long-term health. This is not a reason to start, stop, or switch a supplement from a headline. Educational notes. This is not medical advice.

Evidence level: Review of studies. This is among the stronger kinds of evidence, but one study rarely settles a question.

Read the original at University of Surrey / Nutrition Reviews