In Welsh schools, Marmite is banned in Breakfast clubs in Wales. This is due to it's high salt content. What this decision does not take into account is that Marmite isn't used in vast quantities - it's spread thinly.
(For those outside the UK, Marmite is a by-product of the brewing industry. Made from yeast it is a dark black gooey substance which is spread on toast. It is salty, and high in Vitamin B. Recognising that it's a product you can't be ambivalent about, this is used in the adverts - 'you either love it or hate it'. They show people consuming marmite and half of them have a bad reaction.... lately, Paddington Bear is advertising Marmite.)