Vitamin D Deficiency: Are you getting the “D” you need?

Abstract

Vitamin D is important for muscle and bone health. Vitamin D deficiency is associated with cortical bone loss, increased bone turnover, and increased parathyroid hormone levels, predisposing to osteoporosis. Vitamin D supplementation increases bone density in established deficiency. Historically, the main source of vitamin D was exposure to sunlight. However, changes in lifestyle and awareness of the hazards associated with sun exposure have changed this. Also, Sunscreen sun protection factor 15 (adequately applied) reduces previtamin D synthesis by >99%. At latitudes greater than 35 degrees (MN is at 40 and greater degrees), UVB energy is insufficient to produce vitamin D during the winter months,4 producing a ‘vitamin D winter’ of variable duration, centered on the winter solstice. During these times of no cutaneous vitamin D production, dietary intake of vitamin D and previous vitamin stores become important. Treating deficiency involves correcting the vitamin D deficit and ensuring continuing maintenance of vitamin D status.