A public health professor believes New Zealand schools should run lunch programmes to reduce the consumption of processed and packaged food.

The latest census at school survey shows most school lunches only contain one fruit or vegetable.

AUT's Grant Schofield told Mike Hosking if lunches were prepared and eaten at school, students could receive appropriate nutrients.

He says it's something that works well overseas, where students help prepare and cook wholesome food for lunch.

"The bulk of developed countries have wholesome and decent food, where the kids help make and clean up. It's a really important skill to have."

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