- Vitamin D deficiency is a common health concern worldwide, affecting people across all age groups.
- Vitamin D is a fat-soluble vitamin essential for maintaining calcium and phosphorus homeostasis, which are critical for bone health. It also plays a key role in immune function, muscle strength, and inflammation regulation.
- Deficiency occurs when serum levels of 25-hydroxyvitamin D fall below the recommended threshold, generally accepted to be less than 20 ng/mL (50 nmol/L). Although sunlight exposure is the primary natural source of vitamin D, deficiency can result from inadequate sun exposure, poor dietary intake, malabsorption syndromes, chronic kidney or liver diseases, or certain medications that impair vitamin D metabolism.
- The clinical manifestations of vitamin D deficiency can vary depending on the severity and duration of the deficiency. In children, severe deficiency leads to rickets, a condition characterized by impaired bone mineralization, skeletal deformities, and growth retardation. In adults, it causes osteomalacia, which presents as bone pain, muscle weakness, and increased risk of fractures. Emerging evidence also links low vitamin D levels with an increased susceptibility to infections, autoimmune diseases, cardiovascular disease, type 2 diabetes, certain cancers, and mood disorders like depression.
- Risk factors for vitamin D deficiency include limited sunlight exposure (due to geographic location, indoor lifestyles, or use of sunblock), darker skin pigmentation (which reduces vitamin D synthesis in the skin), obesity (as vitamin D is sequestered in adipose tissue), aging (which decreases the skin’s ability to produce vitamin D), and exclusive breastfeeding without supplementation in infants. Populations at particularly high risk include the elderly, individuals with chronic illnesses, people living in northern latitudes, and those who wear full-body coverings for cultural or religious reasons.
- Diagnosis of vitamin D deficiency is typically made through blood tests that measure serum 25-hydroxyvitamin D levels. Treatment involves vitamin D supplementation, either through oral preparations of vitamin D2 (ergocalciferol) or D3 (cholecalciferol), along with calcium if necessary. The appropriate dose depends on the severity of the deficiency, age, body weight, and comorbid conditions. In some cases, especially in patients with malabsorption or severe deficiency, high-dose therapy may be required under medical supervision.
- Preventive strategies emphasize safe sun exposure, consumption of vitamin D-rich foods (such as fortified dairy products, fatty fish, and egg yolks), and appropriate supplementation in at-risk groups. Given the broad physiological roles of vitamin D, maintaining optimal levels is increasingly recognized as a public health priority, not only for skeletal health but for overall wellbeing. Early identification and management of vitamin D deficiency can help prevent long-term complications and improve quality of life.
