Vitamin D
also known as Vitamin D2, Ergocalciferol, Vitamin D3, Cholecalciferol…
The body makes vitamin D from sunlight on skin. It governs calcium and phosphorus, builds bone and teeth, and supports immune function. Deficiency is common in northern climates and indoor lifestyles.
Recommended daily intake
- Adults 19 70 · 600 IU (15 mcg)
- Adults 71 Plus · 800 IU (20 mcg)
- Pregnancy Lactation · 600 IU (15 mcg)
Upper intake limit
4,000 IU (100 mcg) per day for most adults
Signs of deficiency
- Bone pain, muscle weakness
- Increased fracture risk
- Rickets in children — bowed legs, soft skull
- Osteomalacia in adults — bone tenderness, weakness
- Required for the body to absorb calcium and phosphorus
- Essential for bone and tooth strength across the lifespan
- Helps prevent rickets in children and osteomalacia in adults
- Supports muscle function — low vitamin D is linked to weakness and falls in older adults
- Supports immune cell function
High supplemental doses can cause hypercalcemia, kidney stones, and soft-tissue calcification
Use caution with sarcoidosis or other granulomatous conditions — these can drive vitamin D conversion abnormally high
Use caution with thiazide diuretics, which raise calcium retention
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