Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention.
Level 4 - case-series / case-control
Cross-sectional descriptive study relying on self-reported intake
What was done
This was a descriptive observational study assessing the relationship between self-reported vitamin D supplement intake and serum 25-hydroxyvitamin D [25(OH)D] concentrations in a community-based cohort of 3,667 adults (mean age 51.3 ± 13.4 years).
What was found
Serum 25(OH)D increased with self-reported vitamin D supplementation in a curvilinear manner. No reported intakes of 10,000 IU/day or lower produced serum concentrations exceeding 200 ng/ml (the predefined lower bound for potential toxicity). Baseline unsupplemented all-source input was estimated at 3,300 IU/day. To ensure 97.5% of the population attained a serum 25(OH)D concentration of at least 40 ng/ml, an estimated supplemental intake of 9,600 IU/day was required.
Why it matters
It provides community-level dose-response estimates for high-dose vitamin D supplementation and characterizes serum levels associated with daily intakes up to 10,000 IU.
Limits
The study relied entirely on self-reported supplement intake, introducing substantial risk of recall error and compliance bias. It was an observational, non-randomized analysis that did not directly measure clinical health or cancer outcomes, nor did it experimentally assess safety endpoints beyond cross-sectional 25(OH)D measurements.
Cited by
- supports Vitamin D supplementation has a non-linear dose-response where the first 1,000 IU increases serum 25(OH)D by 4.8–5 ng/mL, while at higher doses (15,000–30,000 IU) each 1,000 IU increases levels by approximately a tenth of that rate.