Infants that are breast-fed without supplementation with baby formula are at high risk of vitamin D deficiency, because human milk is a poor source of Vitamin D.
Premature, low birth-weight infants may be prone to Vitamin D deficiency through their lives as liver and kidney function for Vitamin D metabolism may be inadequate
Elderly people have a reduced ability to produce Vitamin D in the skin by UVB exposure.
Vegans & Vegetarians have limited meaningful dietary sources of Vitamin D3, and supplementation is highly recommended.
People with diseases that affect the thyroid gland, kidneys or liver are at greater risk of deficiency.
Housebound individuals are at great risk of Vitamin D deficiency.
Dark-skinned people produce less Vitamin D3 in the skin by UVB exposure, as the darker melanin provides a natural UV filter.
Individuals located at latitudes of 40 degress north or south are exposed to insufficient levels of UVB sunlight to produce adequate levels of Vitamin D, especially during the winter months.
Individuals that cover-up for religious or climatic regions are at risk, as clothing restricts the skin’s ability to produce adequate levels of Vitamin D through UVB exposure. This is one reason populations in hot and sunny countries such as India are prone to Vitamin D deficiency.
Individuals regularly applying high SPF sun blocks may be at risk of Vitamin D deficiency. Sun protection is of course of absolute paramount importance in sunny, high UV regions, however regular/consistent use of sunblock has been linked to Vitamin D deficiency by restricting the skin’s ability to produce adequate levels of Vitamin D through UVB exposure.