My mom did her PhD in micronutrients (sorry, I never really asked for details) and has always been nagging me to take 10000 IU of Vitamin D a day. I have been

My mom did her PhD in micronutrients (sorry, I never really asked for details) and has always been nagging me to take 10000 IU of Vitamin D a day. I have been remiss in this over the years, and my physicals always come back with a note about being Vitamin D deficient. I have gotten better and my bloodwork comes back normal these days. (I have never noticed an effect. Coffee has a large effect on whether or not I feel awake, and getting exercise has a large effect on whether or not I feel good. But I'm sure not being deficient in Vitamin D is helping something.)