Shorter days mean less sunshine — and for many Americans, that means lower vitamin D levels between October and March. But does everyone need a supplement? Here’s how our pharmacists think about it.

Why winter matters

Your skin produces vitamin D when it’s exposed to UVB light. North of Atlanta, the winter sun sits too low for meaningful UVB exposure, so production drops sharply — even on sunny days.

Who benefits most from supplementing

  • People who spend most daylight hours indoors
  • Adults over 50, whose skin produces vitamin D less efficiently
  • People with darker skin tones, which naturally filter more UVB
  • Anyone whose last blood test showed levels below 30 ng/mL

How much is enough?

For most healthy adults, 1000–2000 IU daily is a sensible winter dose — enough to maintain levels without approaching the safe upper limit. Take it with a meal containing some fat for better absorption.

As always, talk to your doctor or pharmacist before starting any supplement, especially if you take other medications.