Vitamin D Deficiency

Vitamin D deficiency occurs when the body does not have enough vitamin D to support normal calcium absorption, bone health, and immune function. Vitamin D is produced in the skin on exposure to sunlight and obtained in smaller amounts from food, and while Nigeria's abundant sunlight might suggest deficiency should be rare, studies show it is surprisingly common, particularly among women who cover most of their skin for cultural or religious reasons, people who spend most of the day indoors, and those with darker skin, since higher melanin content reduces the skin's efficiency at producing vitamin D from sunlight. Deficiency is often silent for a long time, with symptoms only becoming noticeable once bone or muscle effects are significant.

Many people with vitamin D deficiency have no symptoms and are only diagnosed through blood testing. When symptoms occur: • Bone pain or tenderness, particularly in the lower back, hips, and legs • Muscle weakness or aches • Fatigue • Frequent infections, reflecting vitamin D's role in immune function • In children: delayed growth, bowed legs, or other signs of rickets • In adults: increased risk of fractures from weakened bones (osteomalacia) and a higher likelihood of falls due to muscle weakness

• Limited sun exposure: spending most of the day indoors, consistently covering most of the skin, or living in regions with limited sunlight • Darker skin: higher melanin content reduces the skin's ability to produce vitamin D from a given amount of sun exposure, meaning more sun exposure is needed to produce the same amount • Limited dietary intake: few foods naturally contain significant vitamin D (oily fish, egg yolks, fortified foods), and in Nigeria most staple foods are not fortified with it • Malabsorption conditions: certain gastrointestinal conditions reduce the body's ability to absorb dietary vitamin D • Obesity: vitamin D is fat-soluble and can be sequestered in body fat, reducing the amount available in the bloodstream • Kidney or liver disease: both organs are required to convert vitamin D into its active form

• Consistently covering most of the skin, for cultural, religious, or occupational reasons • Darker skin tone • Spending most of the day indoors • Older age, since the skin's capacity to produce vitamin D declines with age • Obesity • Exclusively breastfed infants without vitamin D supplementation • Chronic kidney or liver disease, or malabsorption conditions

• Rickets in children, causing soft, weakened bones, growth delay, and skeletal deformities such as bowed legs • Osteomalacia in adults, causing bone pain, muscle weakness, and increased fracture risk • Osteoporosis and increased fracture risk, particularly in older adults • Increased susceptibility to infections • Emerging evidence links severe deficiency to other conditions, including some autoimmune and cardiovascular conditions, though this research is still evolving

• Regular, modest sun exposure (typically 10-30 minutes several times a week for lighter skin, longer for darker skin, depending on time of day and skin sensitivity) supports natural vitamin D production • Include vitamin D-rich foods where possible: oily fish, egg yolks, and fortified foods • Vitamin D supplementation is recommended for higher-risk groups, including exclusively breastfed infants, older adults, people who consistently cover their skin, and those with limited sun exposure • Routine screening is reasonable for people with symptoms or in high-risk groups, since deficiency is common and easily corrected once identified