Jacinda Ardern won't commit to making free lunches universal - despite clear evidence it works to keep kids in school

One in five children in New Zealand live in homes that struggle to put good quality food on the table - and for Māori children, it's one in four.

While the Government is trying to combat the issue with its healthy lunch program Ka Ora Ka Ako, only a quarter of schools are targeted.

That's why The AM Show is launching a campaign to ensure all kids across Aotearoa have access to nutritious food in their schools. 

One of the schools benefiting from free lunches as part of the Government's program is Rotorua's Western Heights Primary School. Its principal Brent Griffin says the difference in students has been remarkable.

"It's made a massive difference in attendance and attention," Brent Griffin said on Monday.

"As a school we changed the timetable to shorten our afternoon lessons because students were falling asleep - we could probably go back and restructure that because our kids are now willing and eager participants - it's heartwarming to see."

The difference is night and day - and Griffin says he "couldn't be happier".

But despite overwhelming evidence free lunches work to keep students in school and learning, the Government won't commit to making it universal.

Prime Minister Jacinda Ardern told The AM Show although she, in principle, supports universal free school lunches, it's "a matter of prioritisation".

"I don't have a problem with unlimited lunches. I think that would be great... But I have to prioritise, and it is quite costly to roll out and I have to ask the question 'is that the next step for us?'"

The Government hasn't costed what it would take to provide free lunches across Aotearoa, but Ardern says the current program costs "hundreds of millions".

Currently, Ka Ora, Ka Ako targets 25 percent of schools in New Zealand's lowest decile areas - and Ardern says that's where the focus will stay - for now.

"When we move into universalism you start reaching into pockets where there isn't as much need...but we acknowledge there are families in need in higher deciles schools we're not reaching."