Key messages

  • Nutrition and hydration are fundamental for health and wellbeing.
  • Under-nutrition and malnutrition are common in older people and can lead to serious conditions.
  • 6–8 glasses of fluids per day are recommended for health and body function.

Nutrition is the intake of food and fluid to meet a person’s dietary and biological needs. Good nutrition is fundamental to physical and mental wellbeing.

Under-nutrition occurs when a person is not consuming enough calories or nutrients to meet their energy requirements. It can cause weight loss, health problems, muscle and skeletal loss and lead to serious conditions such as frailty and sarcopenia1. Under-nutrition is more common in older people and can be exacerbated by illness and hospitalisation.

Some causes of under-nutrition include:

  • choosing to eat less
  • medical conditions that affect the absorption of nutrients by the body
  • poverty, social isolation and functional decline that affect a person’s ability to buy food2
  • depression3 and other conditions that affect cognition.

Malnutrition or malnourishment occurs when food and nutrient intake is not appropriate to maintain body function. It can lead to iron deficiency anaemia and sarcopenia.

Common causes of malnutrition are:

  • medical conditions that reduce appetite or impede the person’s ability to care for themselves
  • changes that impact on the swallowing process
  • weight loss and low body weight is common in patients with dementia; in particular those with advancing Alzheimer’s disease.4

Over-nutrition occurs when a person eats more food than their body needs. This can lead to obesity, diabetes and cardiovascular disease.

Hydration is essential to life

Hydration is having enough fluids each day for health and function; 6–8 glasses per day are recommended.

Dehydration can lead to delirium, constipation, urinary tract infections, swallowing problems, falls, inability to regulate medications and life-threatening conditions, especially in people with co-morbidities5.


1. Visvanathan, R., Nutrition in the Frail Elderly, R. Visvanthan, Editor 2014, Aged & Extended Care Services, The Queen Elizabeth Hospital And Adelaide Geriatrics and Research with Aged Care Centre.

2. Shetty, P. Malnutrition and Undernutrition. 2003. 5.

3. Visvanathan, R., Managing nutrition in the elderly: Grief and depression. Editor 2011: N.H. Science, Victoria, Australia.

4. Kurrle, S., Brodaty, H, Hogarth, R, Physical Comorbidties of Dementia. 2012: Cambridge University Press, New York.

5. El-Sharkawy, AM, Sahota, O, Maughan, RJ, Lobo, DN, The pathophysiology of fluid and electrolyte balance in the older adult surgical patient. Clinical Nutrition 2014. 33(1): p. 7.