Factors Affecting Vitamin D Levels

  • Factors related to skin synthesis
  • Lifestyle and individual factors
  • Dietary factors

      Factors Related to Skin Synthesis

  • Reduced exposure to sunlight can lower Vitamin D levels
  • Geographical location; higher the latitude, lower the level of Vitamin D
  • Seasonal variations; deficiency is more common in winter than summer
  • Use of sunscreens is a relatively insignificant factor in terms of Vitamin D deficiency; mainly due to variations in its use. Most sunscreens are designed to block UVA efficienctly but not UVB

Lifestyle & Individual Factors

  • Gender and body fat levels can influence Vitamin D levels
  • Old age can lead to a reduction in the capacity of both the skin and the intestines synthesize Vitamin D Obesity reduces the availability of Vitamin D in the blood because more of the vitamin is stored in fat Smoking can lead to reduced levels of Vitamin D
  • Moderate, on-going, physical activity can increase Vitamin D levels but can prove counterproductive if taken to excess
  • Skin pigmentation; pigmented skin is less able to produce Vitamin D fron sunlight

Dietary Factors

  • Dietary components such as Vitamin A can compete with Vitamin D. High levels of Vitamin A and retinols can reduce the effects of Vitamin D
  • Dietary & injectable vitamin D supplements can increase Vitamin D levels but care should be taken to avoid possible, though rare, vitamin D overdose
  • Medications like Orlistat (Xenical) can interfere with Vitamin D absorption from intestines by causing malabsorbtion of dietary fat
  • Intestinal absorption problems can lead to lower levels of Vitamin D and other fat soluble vitamins but recent evidence suggests that oral supplements may bypass this problem


(9,11,15,16)

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