For most of my life, my vitamin D3 levels were in the high teens and low 20s. My doctor never really thought it was an issue. After Covid, I realized that I was doing myself a disservice by not addressing the situation. On my own, I began to take vitamin D3 4000 IU per day And my level is now over 60 which is where it needs to be as a senior. Always be mindful of the fact that you are the best judge of your own health in the end.