Copper sulfate drops! Made by the instruction of The Copper Revolution author Jason Hommel. 
To learn more about the importance of copper I highly recommend these books! There is so much information on why you need copper in your diet- too much for me to list here without writing a book myself. 
*The Copper Revolution by Jason Hommel 
*Cu-RE your fatigue: The Root Cause & How to Fix it on your Own by Morley Robbins
Both these authors have similar outlooks but both have their own opinions and data to back up their claims on copper and more! Copper has become thee most interesting mineral I’ve have learned about so far and has become a staple in our home!