Vitamin D Factsheet


  • Summary


  • Vitamin D is a fat soluble hormone produced by the skin on exposure to the sun (UVB Sunlight). A small amount (10-15%) is derived from dietary sources.
  • Deficiency is common. Vitamin D has many roles, including building bones, prevention of osteoporosis, regulating the immune system, brain health and muscle strength.
  • Testing and supplementation is recommended if deficient and during winter in Northern or Southern areas of the world.
  • At risk Groups include
    • Elderly
    • Dark skin
    • Housebound
    • Living  above 35 degrees north or  below 35 degrees south of the equator. 
    • Obesity
    • Total Skin covered by clothing


Optimal Health


  • Testing Vitamin D levels is essential particularly if you are in an at risk group.
  • Combine outdoor exercise 3-5 times a week with sun exposed to the arms, legs and head without sun screen for 20 minutes. Avoid the strongest sun period between 11am and 2pm. If you are exposed to the sun, when the sun is at its strongest, you get the beneficial UBV without high levels of harmful UVA. UVA will cause you to burn an may lead to skin cancer. 
  • Supplementation during winter or in an at risk group. 


Symptoms of Vitamin D Deficiency


Levels of 1,25(OH)2D do not typically decrease until vitamin D deficiency is severe.


Impact of Vitamin D Deficiency

  • rickets in infants and children
  • osteomalacia in adults

Associated potential impacts of Deficiency

  • frequent infections or low immunity
  • fatigued and tired
  • bone and back pain
  • depression
  • Wounds heal less well
  • hair loss
  • muscle pain
  • inability to lose weight when overweight


Serum 25-Hydroxyvitamin D [25(OH)D] Concentrations

nmol/L ng/mL Health status
<30 <12 Associated with vitamin D deficiency, which can lead to rickets in infants and children and osteomalacia in adults
30 to <50 12 to <20 Generally considered inadequate for bone and overall health in healthy individuals
50 20 Generally considered adequate for bone and overall health in healthy individuals
75 30 Optimal Health necessary to maximise the effect of vitamin D on calcium, bone, and muscle metabolism
>125 >50 Linked to potential adverse effects, particularly at >150 nmol/L (>60 ng/mL)


Risk Factors 


You may be at risk of Vitamin D Deficiency if  any of the following apply.


  • Breast Fed Infants
  • Elderly or housebound
  • Sunscreen Protection while outdoors
  • Full body Covering
  • Dark Skin, particularly living in northern (above LA, Morocco) or southern latitudes (South of Sydney)
  • Obesity
  • Limited Fat Absorption capacity due to liver disease, cystic fibrosis, celiac disease, Crohn’s disease, and ulcerative colitis


Achieving Optimal Vitamin D Levels


The recommended daily intake to achieve 75nmol/L (30ng/mL) is a daily intake of 1500-2000iu.


Endocrine Society states, to maintain serum 25(OH)D levels above 75 nmol/L (30 ng/mL), adults might need at least 37.5 to 50 mcg (1,500–2,000 IU)/day of supplemental vitamin D, and children and adolescents might need at least 25 mcg (1,000 IU)/day [11].


Food generally provides less than 10% of your daily requirement.


Three sources of Vitamin D

  • Food.  Most individuals will gain 200iu daily from food.
    • Cod Liver Oil 1 teaspoon (1300iu) 
    • Salmon/Trout (600iu)
    • Cearal Fortified (80iu)
  • Exposure to Sunshine UVB
  • Supplementation


Download this Fact sheet / patient hand out here.