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Vitamin

Vitamin D

Also known as: cholecalciferol, D3, ergocalciferol, D2

A
Evidence

Vitamin D is a fat-soluble hormone and micronutrient essential for calcium absorption, bone health, immune function, and cellular regulation. Most people have insufficient levels and may benefit from supplementation, particularly those with limited sun exposure.

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Daily target & upper limit

20 mcg / day · UL 100 mcg

Vitamin D has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:

Vitamin D dosage reference →

Primary uses

  • Bone health
  • Immune support
  • Mood regulation
  • Muscle function
  • Vitamin D supplementation
  • Vegan vitamin D source
  • Bone support
  • Immune function
  • Testosterone
  • Reproductive hormones
  • Implantation
  • Male and female fertility

How it works

  • Acts as a hormone regulating calcium and phosphate absorption
  • Activates vitamin D receptors throughout the body
  • Modulates immune cell differentiation and function
  • Supports muscle protein synthesis
  • Influences neurotransmitter and hormone production

Dosage

Typical range
400-4,000 IU daily for maintenance; 1,000-4,000 IU common in supplements
Timing
Best absorbed with fat-containing meal; timing otherwise flexible
With food
Recommend with dietary fat for optimal absorption
Duration
Safe for long-term use; fat-soluble so accumulates in body—monitor levels if taking high doses
Special populations
Older adults (50+) may need higher amounts (600-800 IU minimum); dark-skinned individuals in northern climates need more; pregnant/nursing women should discuss dosing with healthcare provider

Forms

  • Softgel (oil-based)
  • Liquid drops
  • Spray
  • Capsule
  • Liquid
  • Softgel
  • Vitamin D3
  • With K2
  • D3 liquid
  • D3 softgels
  • UV-B device
  • Cholecalciferol (D3)· 70/100
  • Ergocalciferol (D2)· 70/100
  • Calcitriol (active form)· 70/100
  • D3 (cholecalciferol)· 70/100
  • D2 (ergocalciferol)· 70/100
  • capsules· 70/100
  • tablets· 70/100

Safety

Common side effects

  • Minimal at recommended doses
  • Excessive intake (>10,000 IU chronically) may cause hypercalcemia, nausea, weakness

Contraindications

  • Hypercalcemia or conditions causing elevated calcium
  • Sarcoidosis and certain granulomatous diseases (vitamin D increases calcium absorption)
  • Concurrent high-dose calcium supplementation (risk of toxicity)

Products containing Vitamin D

Top-scoring supplements in our catalog that list Vitamin D on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Momentous
Vegan Vitamin D3 5000 IU Supplement
98
Thorne
Vitamin D Liquid
98
Thorne
Vitamin D-10,000
98
Transparent Labs
Grass-Fed Whey Protein Isolate
98
See all products →

Known interactions

Evidence notes

Strong RCT evidence supports vitamin D for bone health, immune function, and reducing deficiency. Extensive observational data supports broader health benefits. Recommended by major health organizations.

Grade A: Multiple well-designed human trials support the main claims.

Cited research for Vitamin D

Clinical studies referenced across Formulate guides that mention vitamin d. Each links to the full study page with PubMed source + the guides that cite it.

Related in Vitamin

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.