As a kid back in South Africa, my mum always hauled out the jar of Marmite when anyone had an upset tummy or was spewing :( She said that Marmite on toast helps settle the tummy etc. So as a result, whilst I now eat Vegimite in Australia, for me, it still has that nasty association will gastro (thanks mum!!).
I am starting to get over it and I have to say that without it, I don't think I would have survived through my morning sickness! So I love it for a different reason, guess :p
DH (an Aussie) loves it and will have it on toast all the time if given the chance. For some reason, I will always reach for the jam / cheese etc. before thinking of Vegemite. I do, however, really enjoy it with cheese toast or scraped on the toast before I pop a fried egg on :D
So I suppose I disprove the theory that most non-Australians (though I am a citizen now) don't like it :D

