Vitamin D deficiency
Symptoms, at-risk groups, and clinical context for vitamin d deficiency. Sourced from NIH Office of Dietary Supplements and StatPearls.
Vitamin D insufficiency affects an estimated 35-40% of US adults, with higher rates in older adults, people with darker skin, and northern latitudes. Severe deficiency causes rickets in children (irreversible bone deformities if untreated) and osteomalacia in adults. Most cases are subclinical and detected by blood test.
Common symptoms
- Bone pain or muscle aches
- Muscle weakness, especially in the legs
- Fatigue
- Frequent illness or infections
- Mood changes — depressive symptoms (in deficient populations)
- Slow wound healing
- Hair loss
- Bone deformities in children (rickets) — bowed legs, delayed growth
- Often asymptomatic until severe
At-risk groups
- Adults aged 65+ (skin produces less vitamin D from sunlight)
- People with darker skin (melanin reduces vitamin D synthesis)
- People living above 37° latitude (limited UVB year-round)
- Indoor lifestyle, office workers, night shift workers
- People with obesity (vitamin D sequestered in fat tissue)
- Exclusively breastfed infants without supplementation
- People with malabsorption conditions (celiac, Crohn's, gastric bypass)
- People taking corticosteroids, anticonvulsants, or weight-loss drugs
- People who consistently use sunscreen or cover skin for cultural reasons
When to see a doctor: Persistent bone or muscle pain, frequent infections, or unexplained fatigue in any at-risk group warrants a 25-hydroxyvitamin D blood test. Levels below 20 ng/mL indicate deficiency; 20-30 ng/mL is insufficient. Important: do not take high-dose vitamin D (>4,000 IU/day) without lab confirmation — toxicity causes hypercalcemia.
← All deficiencies
Related deficiencies
Nutrients with overlapping symptoms — useful when investigating an unclear clinical picture.