What is the optimal vitamin D status for health?

Prog Biophys Mol Biol. 2006 Sep;92(1):26-32. doi: 10.1016/j.pbiomolbio.2006.02.003.


The most objectively substantiated health-related reason for tanning is that it improves vitamin D status. The serum 25-hydroxyvitamin D concentration (25(OH)D) is the measure of vitamin D nutrition status. Human biology was probably optimized through natural selection for a sun-rich environment that maintained serum 25(OH)D higher than 100 nmol/L. These levels are now only prevalent in people who spend an above-average amount of time outdoors, with the sun high in the sky. The best-characterized criteria for vitamin D adequacy are based on randomized clinical trials that show fracture prevention and preservation of bone mineral density. Based upon these studies, 25(OH)D concentrations should exceed 75 nmol/L. This concentration is near the upper end of the 25(OH)D reference ("normal") range for populations living in temperate climates, or for people who practice sun-avoidance, or who wear head coverings. Officially mandated nutrition guidelines restrict vitamin D intake from fortified food and supplements to less than 25 mcg/day, a dose objectively shown to raise serum 25(OH)D in adults by about 25 nmol/L. The combined effect of current nutrition guidelines and current sun-avoidance advice is to ensure that adults who follow these recommendations will have 25(OH)D concentrations lower than 75 nmol/L. Therefore, advice to avoid UVB light should be accompanied by encouragement to supplement with vitamin D in an amount that will correct for the nutrient deficit that sun-avoidance will cause.

Publication types

  • Review

MeSH terms

  • Canada
  • Dietary Supplements
  • Guidelines as Topic
  • Health Status
  • Humans
  • Nutrition Policy*
  • Nutritional Status
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood*
  • Vitamin D / therapeutic use*
  • Vitamin D Deficiency / blood*
  • Vitamin D Deficiency / prevention & control*


  • Vitamin D
  • 25-hydroxyvitamin D