Vitamin D
also known as Vitamin D2, Ergocalciferol, Vitamin D3, Cholecalciferol…
Supports calcium and phosphorus use, bones, teeth, growth, muscle strength, heartbeat regulation, immunity, thyroid function, blood clotting, osteoporosis prevention, and breast/colon health.
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
- Supports calcium absorption
- Supports phosphorus absorption
- Supports bone health
- Supports tooth development
- Supports growth
- Helps protect against muscle weakness
- Supports heartbeat regulation
- Supports immune function
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Common questions
For most adults ages 19-70, the standard is 600 IU (15 mcg) a day. Adults over 70 are generally advised to take 800 IU (20 mcg). Pregnant and nursing women follow the same 600 IU guidance as other adults.
The upper limit most adults shouldn't exceed is 4,000 IU (100 mcg) a day. Vitamin D is fat-soluble, meaning your body stores extra rather than flushing it out, so consistently going over that limit is more of a concern than with water-soluble vitamins.
Its best-known job is helping your body absorb calcium and phosphorus for bone and tooth health, but it also plays a role in muscle strength, immune function, thyroid function, and normal blood clotting.
It's one of the nutrients most directly tied to bone health, working alongside calcium. Adequate vitamin D is considered a meaningful piece of osteoporosis prevention, though not the only factor.