Ask a Dietitian > Why is hydration important for older people?

Why is hydration important for older people?

January 29, 2019

In this blog post, our expert dietitian, Kaye Dennison (NZRD) explains why hydration is such an important issue for older people and shares her tips on how to reduce the risk of dehydration.

Why do we need hydration?

Water is an essential nutrient which the body loses and cannot produce in the amounts it requires. It accounts for up to 80% of body weight and fills the spaces between cells, supports biochemical reactions and forms structures of large molecules like protein. Water is essential for physiological processes such as digestion, absorption and transportation.

If we do not consume water, or water containing foods or fluids regularly throughout the day, we become dehydrated.

Dehydration occurs in two ways, either the body is short of fluid because of “low intake” and failure to drink sufficient fluids, or due to increased fluid loss, known as “volume depletion” caused by diarrhoea, vomiting or excessive bleeding.

What really happens when we become dehydrated?

In whatever way dehydration occurs, it is serious. In normal healthy adults, thirst is the signal that stimulates us to seek fluids. Thirst is stimulated when osmolality increases or the extracellular volume decreases. Unfortunately, older people often have impaired thirst mechanisms and the signal to seek fluids is defective, which leads to dehydration.

Also, when there is insufficient fluid intake or excessive fluid loss, the kidneys compensate by producing a more concentrated urine to maintain the individual’s fluid balance. However, in older people, the kidney’s ability to concentrate urine is impaired and dehydration occurs.

What are the risks of dehydration?

Older people who don’t drink enough (or have increased fluid losses) have an increased risk of:
– Pressure injuries
– Low blood pressure
– Dizziness and falls
– Cognitive impairment, confusion and delirium
– Constipation
– Urinary tract infections (UTIs) and acute kidney injury

When dealing with hydration its important to note that consistency is key; you want to make sure you aren’t shocking the system by suddenly conuming tonnes of water, you want it to gradually grow accustomed to feeling nurtured and cared for.

-Kirsti Kirk, Internationally Acclaimed Doctor

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Volkert D, et al., ESPEN guideline on clinical nutrition and hydration in geriatrics, Clinical Nutrition (2018),
Wilson L., Hydration in older people in the UK addressing the problem. Understanding the Solutions, The International Longevity Centre- UK, November 2014
Nell, D., Neville, S., Bellow, R., O’Leary, C. Factors affecting optimal nutrition and hydration for people living in specialised dementia care units: A qualitative study of staff caregivers’ perceptions. Australasian Journal on Ageing V 25, Issue 4, pages E1 – E6. 2016
Oates, L.L., & Price, C.I. Clinical assessments and care interventions to promote oral hydration amongst older patients: a narrative systematic review. BMC Nursing 16:4, 2017
Food and Nutrition Guidelines for Healthy Older People – A Background Paper, New Zealand Ministry of Health, January 2013
McIntyre L, Munir F, Walker S, Developing a bundle to improve fluid management, Nursing Times, Vol 108. No 28, 10th July 2012
George J., Rockwood K., Dehydration and Delirium—Not a Simple Relationship
The Journals of Gerontology: Series A, Volume 59, Issue 8, 1 August 2004, pages M811–M812,

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