One substance is experimentally shown to help Fluoride elimination via the kidneys. Tamarind.
http://www.fluoride-journal.com/00-33-1/331-33.pdf
You might buy a jar of tamarind paste/concentrate from an Indian or Thai grocer (its pleasantly sour).
But be careful if your have poor kidneys. Fluoride causes kidney disease; and poor kidney function means you retain more fluoride with potentially disastrous consequences. Only a Renal specialist might be able to say if encouraging more Fluoride to pass out of poor kidneys was wise?
http://www.fluoridealert.org/health/kidney/

Len