Vitamin D Metabolism and Guidelines for Vitamin D Supplementation.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing guidelines and metabolism literature without a systematic review methodology
PubMed 33343045 · doi:10.33176/AACB-20-00006
What was done
This narrative review examined vitamin D metabolism, serum biomarkers including total and free 25(OH)D, factors affecting dose-response supplementation, and differing clinical recommendations published by governments and scientific societies for average adults.
What was found
Government and scientific society recommendations for adult vitamin D intake vary between 400 and 1000 IU/d (10 to 25 μg/d). Serum 25(OH)D response to supplementation depends on baseline levels, BMI, ethnicity, vitamin D form (D2 vs. D3), and genetics. It was not possible to define a target range of serum 25(OH)D concentrations for non-musculoskeletal health outcomes.
Why it matters
It emphasizes the persistent lack of global consensus regarding the definition, measurement, and treatment of vitamin D deficiency, as well as the variability in guidelines across organizations.
Limits
As a narrative review, it lacks a systematic search protocol, risk of bias assessment, and pooled quantitative synthesis. The abstract reports no specific study counts or sample sizes and notes an absence of clear target data for infants, children, and pregnant or lactating women.
Cited by
- supports Supplementation with approximately 1,000 IU of vitamin D generally increases serum 25-hydroxyvitamin D concentrations by about 5 ng/mL.