I will say that - anecdotally - vitamin D suppletion does help with my general feeling of well being during the winter months, though
Vitamin D. Was diagnosed with extreme lack of 2 winters ago. Don't ever want to be in this state again.
Been there, brother 🫂 Fell down the vitamin D rabbit hole ever since. I try to get as much vit D in the summer months as possible and keep track with an app - dminder. Next step is a tan through swimming trunk