It has been found that the capacity for synthesizing Vitamin D decreases with age due to the changes in the skin seen with aging 2). Decreases in oral intake and absorption of Vitamin D in the intestines as well as low 1 alpha hydroxylase enzyme activity in the kidneys, frequently lead to the development of Vitamin D deficiency in the elderly 2).
Around 20% adults may have low vitamin D status. Severe deficiency of vitamin D can result in rickets in children and osteomalacia in adults. The principle source of vitamin D for humans is from synthesis in the skin following exposure to UV light. In the northern hemisphere, the intensity of sunlight required to generate vitamin D in nXDd.