Very good morning doctors. is the normal range for vitamin d 30 to 50 or 20 to 40? i read that both ranges are considered normal levels?

Yes, you are partially correct. The normal value is 30-100 by most lab references but some American medical societies define vitamin D deficiency is less than 20 and below 30 is insufficient. For AA and dark skin people, a level above 20 seems fine to me because the vitamin D level in this population is most often less than 20 and a level below 30 is considered quite low for a white person.

The serum "normal' levels for Vitamin D vary depending upon the lab, and most would say normal is 30 ng/ml or above. In my opinion, focusing upon immune system stability, would optimize your ultimate goals to be between 50-70 ng/ml., if possible.