there is a touch of bromine in the brain, loss of which is associated with parkinsons disease.
i even ran across one time a reference to a possible nutritional need for mercury. the amount cited was a couple of atoms - about what you would get breathing pre-industrial age air.
as for fluorine, it is way too reactive and bound up in the environment for people to have contact with in nature. unleashing the fluoride ion was/is a crime against humanity.