Older people's lives are being put at risk because hospital nurses do not always have time to feed them, a charity warned today.
Age Concern said vulnerable patients were being left malnourished, with their health deteriorating in the very place designed to care for them.
Nine out of 10 nurses did not always have time to help patients who needed help with eating and drinking, a survey of 500 nurses found.
The charity said 60% of older patients - who occupy two thirds of general hospital beds - were at risk of becoming malnourished or seeing their health get worse.
Those aged over 80 were particularly at risk, having a five times higher rate of malnutrition than the under-50s, Age Concern said.
The Royal College of Nursing (RCN) said the findings highlighted the serious consequences of understaffing on hospital wards.
Research shows that malnourished patients stay in hospital for longer, are three times as likely to develop complications during surgery, and have a higher mortality rate.
The cost of malnutrition to the health service is also estimated to exceed £7.3 billion a year, according to figures from the British Association for Parenteral and Enteral Nutrition.
Age Concern's survey coincides with the launch of its campaign, Hungry to be Heard, aimed at "ending the scandal of older people being malnourished in hospitals".
Gordon Lishman, director-general of the charity, said: "Hospitals are in danger of becoming bad for the health of older people.
"The majority of older patients are being denied some of the basic care they need, leaving hundreds of thousands of older patients malnourished.
"It is shocking that the dignity of patients is being overlooked, and that Age Concern has to run a campaign to fight for the implementation of such simple measures.
"From ward to board, everyone needs to address this problem.
"Food and help with eating it should be recognised by ward staff as an essential part of care, and they should be given time to perform this task."
The charity is urging hospital staff to listen to older people, their relatives and carers.
It said all ward staff must become "food aware", assess patients for malnutrition, and implement a "red tray" system whereby patients who need help have their food delivered on a red tray.
Pauline Ford, RCN advisor for older people, said: "This survey by Age Concern highlights just how serious the problem of understaffing on many hospital wards has become and how for so many nurses time has become a luxury.
"It is unacceptable if patients are not getting the help they need to eat or drink.
"Nurses desperately want to be able to give the standards of care they were trained to give but need the support and resources to do so. Most importantly, they need to be given the time to care.
"I am aware of some fantastic examples of nurses leading the way in raising standards for older patients, of nurses listening to and learning from patients and their families, as well as teaching and mentoring student nurses so they learn how to work with older people in a positive way.
"Nurses are already championing improvements for older people, such as introducing protected mealtimes and the red tray system to identify patients who need extra help with feeding. However, much more needs to be done.
"That is why the RCN is calling for protected mealtimes and the red tray system to be rolled out across the UK, for nurses to be given the time and resources to help patients eat and drink, and for directors of nursing to ensure all hospital wards to have the specialist equipment needed to allow those patients who can, to feed themselves independently.
"Nurses who are worried there are not enough staff on wards to help patients eat and drink should report this to their ward manager immediately."