Meals should be more nutritional, ministers say
Prisoners, patients and public sector workers should be offered "appetising and enjoyable menus" at mealtimes, the government says.
Canteens should provide healthier food based on "choice and variety", the Department of Health adds.
Those doing so will get a "Healthier Food Mark", aimed at raising nutritional standards in England.
The government said the public sector had a "duty to look after staff and people in their direct care".
Almost a third of all meals served by UK caterers are provided in public sector institutions, with the NHS alone accounting for about one million a day.
The food marks will be piloted in the NHS, prisons and Whitehall canteens before being extended to all government services.
They encourage less use of saturated fat, sugar and salt, and better presentation.
The guidelines also call for "nutritionally balanced, appetising and enjoyable menus built around choice and variety".
Health Minister Dawn Primarolo said: "Our ultimate aim is for healthy food to be the norm across England - in hospitals, care homes, prisons and in all public workplaces across the country and to ensure that patients are well fed.
"The public sector have a duty to look after their staff and people in their direct care, such as patients and prisoners, so it's essential we serve up healthy and nutritious food."
The government has pledged more than £650m to raise nutritional standards in schools, following a campaign by TV chef Jamie Oliver and concerns over childhood obesity and other health issues.