Paprika will NOT darken or reverse the bleaching that's already happened to the coat. It can only prevent
it from happening, so you need to start feeding it early in the spring, before the winter coat completely sheds. Once the color has bleached there's nothing that can bring it back.
The copper in paprika is what gives the coat "sunscreen". Copper is very good for the skin (bonus- if you have a horse that's prone to getting the bacteria "scratches", copper has been shown to help clear it up from the inside out) and healthy skin = healthy coat:)
Capsaicin is a substance in peppers, and a natural pain reliever, which is why it's banned from use in rated horse shows. If you're feeding your horse paprika and plan on going to a rated show, you need to stop it at least 2 weeks before. Of course if you stop feeding it, your horse will be susceptible to bleaching during that time.
Typically you need to feed between 1 to 2 tablespoons a day. You can buy bulk sizes at places like Sam's Club, or American Spice online also has larger tubs. Hungarian Paprika typically has a higher copper content, but make sure you're getting the sweet stuff, not the spicy kind!
Uckele makes a copper supplement that I'm going to try out. Hopefully it works! Poly Copper