There are many things but the number one thing to consider first is, are you drinking water with Flouride?
Are you brushing teeth with Flouride?
When I made sure I was no longer getting flouride in my body, the dark circles went away! :-)
Cleansing and nurishing the body is key.
If you are not on any iron medications, you may want to also consider 1 Tbs. Organic Unsulphured Black Strap Molasses daily which is the RDA recommended amount, and in a food form, a big difference.
Just about every woman should take this daily...
Just a few healthy suggestions, hope these help :-)