It's the serum level of activated vitamin D that matters, not your intake which may not even be absorbed properly. (You need to have sufficient magnesium for in

It's the serum level of activated vitamin D that matters, not your intake which may not even be absorbed properly. (You need to have sufficient magnesium for instance). That there will be large variations in outcome is indicated by this conclusion from Nutrients 2020, 12, 1268 In 238 healthy adults (18-64; 50% male,female) screened for serum 25-OH-VitD concentration "two months of treatment with 25 µg (1000 IU) daily was not sufficient to assure recommended serum 25-OH-vitD levels in all subjects"