We've come a long way in what we know about eating well, so "just like you and I had" is not good enough any more, experts say.

Prime Minister Christopher Luxon’s suggestion of a Marmite sandwich and an apple for lunch wouldn’t keep a child full or feed their brain sufficiently, according to local health and education experts.

“If you’re just doing a Marmite sandwich and an apple, you’re probably not meeting the protein requirements [which depend on age and gender],” paediatric dietician Jenny Douglas explained to RNZ.

“Ideally it would be a Marmite and cheese sandwich at least,” she said, noting that the high salt content of Marmite, which could shape one’s palate, giving a child a taste for salty snacks like pies and chips early on.