[1_player]

Here in UK, like everywhere else, Vitamin D dosage is measured in IU.

You probably never noticed it, or your pills have low-strength dosages (400 IU), which are quite common to find in pharmacies, and personally I don't even bother with those.

[matsemann]

On my bottle it just says "Vitamin D: 15 μg" on the bottle.

Apparently 1 μg = 40 IU for vitamin D, but different per vitamin.