Consumers in Auckland, Wellington and Dunedin are paying more than in other cities to buy healthy food.
The latest Food Cost Survey, conducted annually since 1972, shows the price for a family of four has increased by between $4 and $21 over the last year.
Christchurch is the only city to have bucked the trend, becoming cheaper by $3, research from the University of Otago showed.
The biggest price increase came in Auckland, up $21 on last year.
A family of four with a teenage boy and ten-year-old boy would spend nearly $260 a week on "basic" healthy food costs.
A one-year-old would cost $29 to feed for a week, increasing to $74 for an adolescent male
Lead researcher, Louise Mainvil said the price is worrying, costing someone with a fulltime job on a minimum wage 42 percent of their weekly income.
"Anytime that figure goes above 30 percent, that's when there is stress on the food budget," she said.
"If more than 30 percent goes on food, then that puts more pressure on the family if a child needs a new pair of shoes for school or the car needs a warrant of fitness.
"People on minimum wages have difficulties paying the rent and buying food."
Thirty-one percent of the cost is made up of fruits and vegetables, 28 percent on meats and proteins and another 13 percent for dairy.
They found low-income families are more likely to have a poorer diet through replacing expensive health foods, with options that cost less but fill children's stomachs.
"It's cheap to get calories, but in reality it's expensive to get the nutrients," she said.
Healthy food costs in Wellington went up $10 and Dunedin, just $3 over the last year.
Basic healthy foods covered in the study included :
- Fresh, canned and frozen fruit and vegetables
- Meat, poultry and fish
- Breakfast cereals
- Tea, coffee, milo and sugar
- Pasta, rice and flour
- Fats and oil,
- Cheese, milk, yoghurt,
- "Other foods" including tomato sauce and plain water crackers.