There are 2 classes of vitamins, water soluble and fat soluble.
Your body needs both kinds to function properly, they are essential to maintaining good health. Just as the labels imply, water soluble vitamins dissolve in water and fat soluble vitamins dissolve in fat.
Water soluble vitamins are not stored in the body, they get flushed out in our urine. We need to make sure we replenish these daily. The Ketogenic diet requires you to drink a lot of water and therefore we flush our water soluble vitamins out, to stay healthy we need to add in daily supplements. Water soluble vitamins are also affected by storage and cooking.
Fat soluble vitamins dissolve in fat before they are absorbed and used by our bloodstream. These vitamins are stored in our liver. It is not a good idea to over consume the fat soluble vitamins because they are stored.
It is always best to try to get your vitamins from the foods you eat, but when you cannot, supplements are necessary.