prettysoulful reminded me that copper works closely with calcium and potassium. I have found this to be true. I have some early grey and just recently some of my brows have been showing up grey. When I increase my calcium, potassium while at the same time limiting foods/supplements that inhibit potassium I notice that my brow hairs grow back dark. Could be something else though, but Im pretty sure potassium is necessary for my particular problems.