I heard that Mozquitos don't like people who eat Marmite*, can't remember where I heard it, but it was fairly recently (last few months or so). I don't really know if it is true, but I'm a Marmite lover and I never get bitten by insects.

I have just done a search and found this. It might be the B vitamins in Marmite that has the repellent effect.

* For those who don't know, it is a savoury yeast extract spread typically used in sandwiches or toast.