Marmite supplies are on a knife edge, with lovers of the spread being urged to ration their use as supermarkets run low on stock.
Manufacturing of the popular breakfast spread has been halted by earthquake damage to Sanitarium's Christchurch plant - the only plant where Marmite is made.
Sanitarium is urging consumers not to "freak out" as it works to relocate its Marmite manufacturing facilities to a safer part of the Christchurch site.
But it is asking consumers to ration their Marmite use while supplies are spread thin.
The "Marmageddon" as wags on the Internet quickly dubbed it became a hot topic on Twitter, where "Marmite" was the top trending phrase in New Zealand tonight, with fans and foes of the spread debating how to deal with a shortage.
"Have not eaten Marmite in years. Now I'm starting to wonder how I will make it to July without a jar," wrote DJ Dominic Harvey.
"It's important to hold onto the memories - like the marmite and walnut sammies mum used to send me of to school with #ripmarmite," wrote 3News' Hilary Barry.
"The last 20 tweets I've seen from my NZ contacts are talking about the #Marmite shortage," wrote Richard Cotman from France. "Truly, nothing happens in my home country."
Sanitarium general manager Pierre van Heerden said people should consider spreading it on toast rather than uncooked bread to make it last.
"With toast, it's a little bit warmer so it spreads easier and it goes a little bit further," he told Radio New Zealand.
"So what we're asking consumers is maybe if they could have their Marmite on toast, ration it a little bit, maybe have it only once a day or every second day until such time as we can have full Marmite stocks back out in the marketplace again."
Mr van Heerden said there was still some stock in retailers' distribution centres and on supermarket shelves.
"Certain sizes have totally run out and last week, at the end of last week, we sent our last stocks out to the distribution centres of the retailers."
But he urged consumers not to "freak out about it".
"We will get Marmite back, we will be producing it in New Zealand, it will be the same product that we've all come to love."
Mr van Heerden said a manufacturing tower at Christchurch the plant had been severely damaged in the earthquakes and was in the process of being deconstructed.
"What we've been doing since we discovered that is working really hard and our prime focus has been to make sure we can get our Marmite plant relocated into a safe area on-site."
Deconstruction of the tower was proceeding well, he said.