Despite malnutrition affecting half of all aged care residents in Australia, facilities are cutting back on food spending to increase profits.

That's according to a Queensland university which found an almost 5 per cent (31 cents per day) drop on food spending per person over a 12-month period to $6.08 per resident per day, and that on average more money is spent feeding a person in jail ($8.25 per day).

The research, from the Faculty of Health Science and Medicine at Bond University, also shows that while spending on fresh food has fallen there has been a rise in the amount spent on supplements and food replacements.

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The study report says malnutrition is associated with a "cascade of adverse outcomes" including an increased risk of falls, pressure injuries and hospital admissions.

While diminished sensory perception and the physiology of ageing may increase malnutrition risk, it says there is "emerging evidence that food insecurity or the limited ability to access safe, tasty, nutritious and culturally appropriate food" may also be causes of malnutrition in care.

The researchers surveyed 817 residential aged care facilities, representing about a third of residential beds.

They found the average amount spent on food each day for residents was less than some other countries including the US ($A8.98) in 2014, the UK ($A6.12) Norway ($A22.86) and Canada ($A8.63). The daily food budget per resident had increased in these countries over recent years.

The study authors say it is likely aged care providers are choosing supplements and food replacements over fresh food and ingredients in response to "unintentional resident weight loss" despite evidence of the benefits of fresh food.

Combined Pensioners and Superannuants Association spokesperson Paul Versteege said the industry, and particularly federal Aged Care Minister Ken Wyatt, should start putting residents' wellbeing first.

According to 2014 Australian Bureau of Statistics figures, older people in the general community spent $17.25 per person per day on food and drink despite having similar energy and protein needs to those in residential aged care facilities. Adults under 35 spent about $18.29 on food per day.

Industry bodies Leading Age Services Australia and Aged and Community Services Australia had not responded to The Senior as we went to press.