Food prices fell 0.5% in August compared with the same month last year.
It is the fourth consecutive monthly fall compared with 2011, figures from Statistics New Zealand showed.
Although the annual cost is down, prices in August were 0.1% up on July.
This was led by a 1.5% increase in fruit and vegetables, while non-alcoholic beverages rose by 1.3%.
Restaurant and ready-to-eat food fell 0.1% and grocery prices were 0.7% down.
ASB economist Jane Turner says weaker commodity prices have kept food prices down, but an overseas climate event could affect that.
Ms Turner says prices will rise again in the coming months. "We do think that this fall will be limited. We have started to see commodity prices stabilise, and we don't expect them to lift over the next 18 months."