Kiwis have been scraping Marmite onto toast for more than a century — the New Zealand version has been on pantry shelves since 1910 — and the debate over whether it's actually good for you finally got a proper answer from three registered dietitians and nutritionists speaking to NZ Herald. The verdict? Better for you than you might expect, with one clear catch: salt.

The spread is made from concentrated brewer's yeast, a byproduct of beer fermentation, plus sugar, salt, caramel colouring, a few functional additives and added iron and B vitamins. A single 5g serve delivers 25% of an adult's daily B12, half the daily B1, and solid amounts of B2, B3 and folate — genuinely useful numbers, not token gestures. That B12 matters most for vegetarians and vegans, since the vitamin usually comes only from animal products. There's also 1.8mg of iron per serve, a handy bonus for anyone skipping meat.

Dietitian Julia Sekula cautions against treating it as a supplement, though. Vitamins should come from varied whole foods, with Marmite as a flavourful extra. And anyone with coeliac disease or wheat allergy should skip it: the brewer's yeast can be exposed to barley and wheat during processing.

The real watch-out is sodium. Each serve carries 166mg, against a recommended daily maximum of 2000mg for adults and just 1000mg for toddlers — worth remembering since the stuff is popular in daycares as a nut-free, low-sugar option, typically layered onto already-salty bread with salty butter. A thin spread is the sensible move. On the plus side, sugar is negligible (0.6g per serve) and the salt doubles as a preservative, so an open jar keeps for years.

Then there's the trans-Tasman rivalry. Australia's Vegemite, invented in the 1920s during wartime shortages of British Marmite, is similar on B vitamins but doesn't list B12 or iron — so the local product arguably wins on nutrition, though reduced-salt and kids' Vegemite versions do add B12. Health-wise, experts say the difference is marginal and it comes down to taste. (Veteran travellers may also remember Marmageddon, the 2012 shortage when earthquake damage to Sanitarium's Christchurch factory left shelves empty.)

For visitors, this is a fun slice of Kiwi food culture: try it on buttered white toast at a café or grab a small jar as a souvenir — and go easy on the first spread. It's a strong, savoury flavour that divides rooms.