Marmite turns out to be a UK sandwich spread made from brewer's yeast
Marmite is recognised by the British as a national icon unavailable abroad, and is always one of the items taken in food parcels when visiting expatriates. This practice features in literature and in folk lore as much as in reality. For example, my daughters invitation to her going-away-to-Germany party next weekend has the line "Missing Marmite already".
Marmite run a series of ads under the common theme "love it or loathe it". One shows a girl sneaking a quick bite of a marmite sarny before returning to snog her boyfriend who immediately starts gagging.

Does Vegemite have the same connotations for our Oz and Zildean cousins?