I've been noticing that the more I do things that generally remove toxins and heavy metals, the whiter my hair. If you look at all the vitamin c doctors they all went grey early. To me two possibilities seem likely, key metals are being removed as well or some heavy metals(or fluoride) are building up and are hard to remove from the follicle(thus causes excessive peroxide). I tend to think its toxins. But time will tell. I saw one person for whom Iodine and Epsom Salts did wonders..those two things strongly target mercury.