I do not know but I have read and heard on podcasts that you need good vitamin D levels, 30 or above in whatever units it is measured, for longevity. I have also heard that it acts as a hormone in the body but do not remember any details. Look up the podcasts by Rhonda Patrick, PhD, as she covers Vit D extensively.

Are you taking 2000 IU every day? Remember to take them with fat as it is a fat-soluble vitamin.