Egg yolks are nature's multivitamin. Full of fat soluble vitamins A D E K as well as biotin and choline. I supp magnesium too bc it's drained from our food supply and our body needs it in over 3700 enzymatic reactions including using vit D. So if you're supping vit D and not seeing a rise in levels, supp magnesium too. Preferably glycinate, taurate, or orotate imo.