My vitamin d level is 19ng/ml the lab reference is 30-100. nih website says 20ng/ml is adequate, and above 50 has adverse effects, but md says above 30 is optimal. do i need to supplement and how much? md advised 5000 iu/day, i think it's excessive?

Levels of 50 nmol/L (20 ng/mL) or above are adequate for bone and overall health. Levels below 30 nmol/L (12 ng/mL) are too low & might weaken your bones & affect your health. Levels above 125 nmol/L (50 ng/mL) are too high and can cause health problems.For you, the 19 is too low and should be increased and initially increasing with 5000 IU per day for about a month, then 1000 IU per day usually.