Between October and March, the sun in Copenhagen is too low to make vitamin D. Most of our members drop below range by February.
The winter dip is predictable
Across members who tested in both summer and winter, vitamin D fell by about a third. The drop started in November and bottomed out in February.
82 mg/dL
Average winter drop
7 in 10
Nordic members below range in February
How much to take
For most adults, 1,000 to 2,000 IU a day with a meal keeps levels in range. Testing in late winter shows whether your dose is enough.
“If I could add one number to every routine check-up, it would be ApoB.”
A simple winter routine
Start a daily supplement in October
Take it with your largest meal
Test again in February
Stop or lower in summer
IN THE LIBRARY
Vitamin D: ranges, trends and what moves it
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