Does anbody know how to make grout inbetween the tile white again?

[ScrewballMuppet]

I'm sorting out the bathroom today and though the grout isn't bad its been a few shades of pink over the past year (have been studying and working grout last thing on mind) and though I normally can get rid of it with a toothbrush and a good scrub; it seems to be discoloured for good now.
Any ideas?

And for mildew, the Astonish mould and mildew stuff does a brilliant job.

The same as Paradise. It really is good and cheap.