New Zealand's rate of gastroenteritis caused by eating unsafe food costs the country $86 million a year in lost work days alone, says the national Food Safety Authority.

About 40 per cent of the problem is estimated to be due to poor food handling in the home. The authority's new guide, Food Safety in the Home, contains safety tips with practical steps to help avoid a food-borne illness.

The golden rule of food safety is the 4Cs (clean, cook, cover and chill).