Vitamins

Vitamin D

The sunshine vitamin essential for bone health, immune function, and mood regulation

Quick Facts

Daily Needs

600-800 IU (15-20 mcg) per day for adults, with higher needs for older adults

Importance

Vitamin D is crucial for calcium absorption, bone mineralization, immune function, and may help prevent various chronic diseases.

Key Functions

  • Calcium absorption for bone health
  • Immune system regulation
  • Cell growth and division
  • Neuromuscular function
  • Inflammation reduction
  • Glucose metabolism support

Deficiency Signs

  • Bone pain and tenderness
  • Muscle weakness and aches
  • Fatigue and tiredness
  • Mood changes and depression
  • Impaired wound healing
  • Increased susceptibility to infections
  • Hair loss
  • Bone loss and increased fracture risk

Excess Signs

  • Hypercalcemia (excess calcium in blood)
  • Nausea and vomiting
  • Weakness
  • Frequent urination
  • Kidney stones
  • Kidney damage
  • Calcification of soft tissues

Best Food Sources

  • Fatty fish (salmon, mackerel, sardines)
  • Cod liver oil
  • UV-exposed mushrooms
  • Fortified foods (milk, orange juice, cereals)
  • Egg yolks
  • Beef liver
  • Cheese

Absorption Facts

  • Fat-soluble - best absorbed with dietary fat
  • Sunlight (UVB) exposure triggers vitamin D synthesis in skin
  • Darker skin requires more sun exposure to produce same amount
  • Absorption decreases with age
  • Obesity reduces bioavailability

Special Considerations

  • People in northern latitudes often need supplements in winter
  • Those with limited sun exposure are at higher risk of deficiency
  • Sunscreen blocks vitamin D synthesis
  • Older adults have decreased synthesis capacity
  • Those with fat malabsorption disorders may need specialized forms

About Vitamin D

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