I carry two tubes of horse paste with me wherever I go, and my vitamin D blood concentration is 44.3 ng/ml, on the way to a targeted 50 ng/ml.
https://www.medrxiv.org/content/10.1101/2021.09.22.21263977v1
What are you doing for the D?
Mine hovers between the high 50s and high 60s and has for more than 10 years. It has improved remarkably since I retired and am outside in the sun for sustained periods of time now. Working in an office was not helpful and I had to stay on top of it starting out at 18 ng/ml. I have to remind the doc to check it during my physicals I’ve managed it since the youngster in Boston wrote his paper in NEJM that got so roundly hammered by the establishment and was later, much later proven right.
Poultry medicine has known about the benefits of D3 for a long time in prevention of disease in flocks, one thing being respiratory disease of the covid flavor.