The crunch of healthy salad has more bite with data from Statistics New Zealand showing that the price of lettuce is up 77 per cent from last month.

Overall, the price index showed vegetable prices rose 9.2 per cent in the month, with higher prices for tomatoes (up 30 per cent), and broccoli (up 24 per cent) sitting alongside lettuce as the biggest contributors.

The price of a 500g head of lettuce was $5.42 in July 2018, compared with $3.07 in June 2018, and $3.30 in July 2017.

A 7.9 per cent fall in fruit prices partly offset the rise in vegetable prices.

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"Lettuce prices are now at their highest since the series began, and 2.5 per cent higher than their previous peak in May 2017," consumer prices manager Geraldine Duoba said.

"July was particularly cold and wet in the North Island where a lot of our lettuce is grown."

Across all categories, Statistics New Zealand said food prices rose 0.7 per cent in July and 1.1 per cent on the year.

Duoba also pointed out there were also price increases in the restaurant and ready-to-eat market, which had an annual lift of 3.2 percent.

Stats NZ had previously said that for every $100 that Kiwi households spend on food, about $26 goes on takeaways and eating out. That's in line with the Business NZ-BNZ performance of services index, also released today, which showed a recovery in services activity last month, supported by strength in accommodation, cafes and restaurants, which are typically linked with a healthy tourism industry.

The Stats NZ data show grocery food prices were flat on the year while milk, egg and cheese prices dipped 0.8 percent.

The food price index accounts for about 19 per cent of the consumers price index, which is the Reserve Bank's mandated inflation target when setting interest rates.

Last week the central bank kept the official cash rate at 1.75 per cent and said it expects to keep interest rates at stimulatory levels for longer, given tepid growth and inflation. The central bank is now forecasting a full rate hike by December 2020.

- Additional reporting by BusinessDesk.