Vitamin D (also referred to as calciferol) is a fat-soluble vitamin that has essential roles in the metabolism of calcium and phosphorus and is thus critical for bone growth and bone mineral metabolism. Vitamin D is naturally present in a few foods and is also produced endogenously when ultraviolet (UV) rays from sunlight strike the skin and trigger vitamin D synthesis.1,2
Vitamin D deficiency occurs when the body doesn’t have enough vitamin D to maintain calcium absorption and bone metabolism.1,2
Vitamin D deficiency is a global public health issue. Hypovitaminosis D affects all age groups, from the newborn to the elderly, and is dependent on several lifestyle and environmental conditions. Even in sunny climates, deficiency can occur due to sunscreen use or limited outdoor activity.3
Vitamin D deficiency is known to cause two metabolic bone diseases, rickets (in children) and osteomalacia (in adults). Although vitamin D deficiency may not always cause noticeable symptoms, common signs can include: 2,4,5
Vitamin D deficiency is known to cause two metabolic bone diseases, rickets (in children) and osteomalacia (in adults). Although vitamin D deficiency may not always cause noticeable symptoms, common signs can include: 2,4,5
Vitamin D deficiency is known to cause two metabolic bone diseases, rickets (in children) and osteomalacia (in adults). Although vitamin D deficiency may not always cause noticeable symptoms, common signs can include: 2,4,5
Vitamin D deficiency is known to cause two metabolic bone diseases, rickets (in children) and osteomalacia (in adults). Although vitamin D deficiency may not always cause noticeable symptoms, common signs can include: 2,4,5
Vitamin D deficiency is known to cause two metabolic bone diseases, rickets (in children) and osteomalacia (in adults). Although vitamin D deficiency may not always cause noticeable symptoms, common signs can include: 2,4,5
Several factors can contribute to low vitamin D levels: 6
1.National Institutes of Health (NIH) – Office of Dietary Supplements. Vitamin D Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ (Last accessed: July 16, 2025)
2.Roth DE et al. Global prevalence and disease burden of vitamin D deficiency: a roadmap for action in low- and middle-income countries. Ann. N.Y. Acad. Sci., 2018, 1430: 44-79.
3. Mithal A et al. Global vitamin D status and determinants of hypovitaminosis D. Osteoporosis International 2009;20(11):1807–1820.
4.Kennel KA et al. Vitamin D deficiency in adults: when to test and how to treat. Mayo Clinic Proceedings 2010;85(8):752–758.
5.https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency (Last accessed: July 16, 2025)
6.Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Dermato-Endocrinology 2013;5(1):51–108.
