UPDATED 4.02PM: Common nutrition standards will be brought in across Auckland's three district health boards, following a decision to contract out all food services.

Staff at Auckland Hospital abandoned work today when they learnt of the decision to outsource work to Compass Group.

Auckland DHB says good nutritious food is a medicine, and common standards have been developed which include nutritional goals, menu structure and even what crockery and cutlery is used.

It says a common audit system and patient satisfaction surveys will also be introduced for the first time.

The 15-year contract is expected to save up to $90 million.

Compass Group currently provides 44 percent of all patient meals in New Zealand.

Under the agreement, its responsibilities in Auckland will include food supplies for wards and departments, cafeteria services, and Meals-on-Wheels.

Angry and upset staff at Auckland Hospital have walked off the job today after learning of the decision.

Service and Food Workers Union spokeswoman Jill Oven says workers are calling on the Auckland Metro District Health Boards to reconsider their decision.

"It's about patient safety, it's about the whole community.

"It's not just about the finances. The DHB has other obligations to our community."

Jill Ovens says Auckland Hospital staff are so angry, stressed and upset by the news, many may not return to work tomorrow.

However, Auckland DHB's chief executive Ailsa Claire says the agreement will enable the Auckland, Waitemata and Counties Manukau DHBs to improve food quality and manage costs in the face of a rising population.

Ms Claire is assuring Food Service workers the DHB will do its best to work with the new provider, Compass, to give staff certainty about the future.

She says there will be no kitchen closures and all DHB food service staff will be offered the opportunity to transfer their employment to Compass Group on the same terms and conditions.