Vitamin D helps your body absorb calcium, supports immune function, and may influence mood. Many adults are deficient — especially those who spend little time outdoors or live at northern latitudes.
Why deficiency is so common
- Skin produces less vitamin D from sunlight with age.
- Reduced outdoor activity and sunscreen use limit synthesis.
- Kidneys convert vitamin D less efficiently.
- Certain medications affect absorption.
Signs you might be low
Fatigue, bone pain, muscle weakness, and frequent illness can suggest deficiency — but symptoms are often subtle. A blood test (25-hydroxyvitamin D) is the only reliable way to know.
How much do you need?
Guidelines vary. Many experts suggest 800–1,000 IU daily for most adults, sometimes higher if deficient. Food sources include fatty fish, fortified milk, and egg yolks — but diet alone rarely suffices.
Supplements: practical advice
Vitamin D3 is commonly recommended. Take it with a meal containing fat for better absorption. Pair with adequate calcium unless your doctor advises otherwise.
Don’t overdo it
Very high doses can cause calcium buildup and kidney problems. Test, supplement appropriately, and retest as directed.
Talk to your healthcare provider before starting supplements — especially if you take heart medications or have kidney disease.
Medical disclaimer: This article is for general information only and does not replace advice from your doctor or qualified health professional.