In animals, copper supplementation can restore natural colour to white hair, and in one experiment, it increased longevity.
At present, there isn't enough knowledge about the safety of different ways of administering supplemental copper. It can be toxic, and it oxidizes other nutrients.
Besides choosing foods high in copper and low in iron and other heavy metals, other dietary choices which support thyroid function will tend to promote the retention of copper.
Other dietary practices can minimize our production of cortisol (e.g., combining fruits and proteins, since protein foods lower blood sugar and stimulate the secretion of cortisol).