From: The importance of vitamin D in maternal and child health: a global perspective
Risk factors that limit skin exposure to UVB rays | Â |
 Latitudes above 40° north |  |
 Winter season |  |
 Exposure in early morning and evening (before 10 AM, after 4 PM) |  |
 Cloud cover and atmospheric pollution |  |
 Limited time spent outdoors |  |
 Customary dress that conceals large portions of the body |  |
 Sunscreen use |  |
 Dark skin pigmentation |  |
 Older age |  |
Risk factors that limit dietary exposure to vitamin D | Â |
 Low dietary intake of oily fish and egg yolks |  |
 Vegetarian diets |  |
 Low/no dietary intake of vitamin D fortified foods |  |
 Exclusive breastfeeding in infants |  |
 No intake of vitamin D supplements |  |
Other risk factors that alter vitamin D supply or metabolism | Â |
 Vitamin D status of infant depends on vitamin D status of mother during pregnancy |  |
 Low dietary calcium intake |  |
 Obesity |  |
 Genetic factors that affect vitamin D physiology and requirements |  |
 Poor renal function |  |
 Liver disease and cholestasis |  |
 Chronic disease |  |
 Malabsorption (coeliac, inflammatory bowel disease, cystic fibrosis, etc.) |  |