Dirty hospitals are serving out-of-date food to patients, an investigation has found.
Meals are being prepared in mouldy kitchens, putting vulnerable patients at "high risk" of food poisoning, while others have unclean worktops, food trolleys and sinks.
Food hygiene reports obtained by the Press Association under the Freedom of Information Act and data from the Food Standards Agency (FSA), also revealed poor rankings for hundreds of care homes and children's nurseries.
Some 400 hospitals, hospices, care homes, nurseries and school clubs are currently listed as needing "major", "urgent" or "necessary" improvement.
One care home was infested with cockroaches while another had evidence of rats.
The Patients Association has called the findings "shameful" and "immensely worrying".
These institutions are treating and caring for some of the most vulnerable people and children in society. To either overlook or neglect the standards of good food hygiene is shameful.
The Food Hygiene Rating Scheme - which rates organisations and businesses from zero to five - is run by the FSA and councils in England, Wales and Northern Ireland.
The investigation found:
Eight health and care premises currently have a zero rating - which means urgent improvement is necessary. None are hospitals.
Some 187 have a rating of one - which means major improvement is necessary. Three of these are hospital premises, including the private Priory Hospital in Altrincham, Cheshire.
And 205 are ranked as two - improvement necessary. They include six hospitals and about 100 care homes. Among those given the ranking of two was Glenfield Hospital in Leicester.
At Glenfield Hospital in Leicester, an inspection of its kitchens serving patients found:
Sliced chicken two days past its use-by date.
Staff had created their own date labels for when they thought food should be used, creating a "high risk" for patients who might develop food poisoning.
The experts also found leaking sinks, "inadequate" knowledge among staff about how to handle food safely, and mouldy areas, including the salad preparation room.
Food was being kept in fridges with temperatures up to 13C despite rules saying they should be 5C or below to prevent bacteria developing.
Darryn Kerr, director of facilities at Leicester's Hospitals, said the organisation was "disappointed" by the ratings.
He said catering services were brought back in-house in May after being run by an external provider.
We take these matters very seriously and acknowledge the issues noted within the report. We already have an action plan in place to urgently address the areas that need improvement. >
Parkview Residential Care Home in Bexleyheath, south-east London, was found to have an "infestation of Oriental cockroaches" during an August inspection.
The kitchen was closed voluntarily for the second time following a previous warning and inspectors gave it a zero rating.
Ivy House care home in Derby, which specialises in dementia care, scored zero after inspectors found evidence of rat activity.
The home said the problems have now been rectified and related to an outbuilding.
Elsewhere, Hulton Care Home in Manchester was given a rating of one in August. Inspectors found raw meat being kept incorrectly and repairs needed.
A spokesman said it was awaiting a new rating, adding: "Following the inspection we worked with our catering partner Elior UK and quickly made the required improvements.
An FSA spokeswoman said: "The food safety officer from the local authority will be taking the necessary action to ensure that the issues identified at caring premises with a lower rating are addressed and that vulnerable people are not put at risk."