Ageing is accompanied by increased likelihood of having acute illnesses (e.g. heart attack, chest infections) and chronic conditions (e.g. stroke, Parkinson's Disease, dementia). The older person with severe acute illness may have delirium (confusion). These conditions may affect appetite, functional ability or ability to swallow.

Older persons with dementia and stroke may experience impaired ability to interpret sensations such as smell, taste and touch. They do not understand what they should eat and what they should not eat.

Multiple medications in chronic conditions can have a detrimental effect on nutritional status through side effects such as loss of appetite, dry mouth, nausea, diarrhoea, tiredness and reduced gastrointestinal motility.