The challenge with hydration for the elderly

Maintaining proper hydration is universally important, but those over the age of 65 are at greater than average risk for dehydration.

Prevention and quick amelioration of dehydration is a crucial component of care for the older adult.

Dehydration leads to a lack of water in the cells that correlates with an increase in osmolarity, or the concentration of solid particles outside the cells, which causes a cascade of negative effects.

Disruptions in water and electrolyte balance can lead to decreased muscle strength, renal failure, and increased risk of falls.¹ In addition, dehydration has been linked to a decline in cognitive function and mood.²

Incidence of Dehydration in the Elderly Population

Conservative estimates put the prevalence of elderly adults that are currently dehydrated at 20%. The European Society for Parenteral and Enteral Nutrition (ESPEN) states that over ⅓ of aged adults in residential care facilities may be dehydrated.^{1, 3} In hospitalized patients, this statistic jumps as high as 40%.⁴

The cause of dehydration in older adults is multifactorial. As people age, thirst sensation reduces and thirst’s osmotic set point increases. This means that older adults will feel thirsty later and drink less than younger individuals.⁵

Another area of concern is the decline of the body’s ability to concentrate urine. In older adults, urine osmolality and the ability to conserve solutes decreases by 20% and 50% respectively.^{5, 6}

Thus, elderly excrete a greater proportion of the water and electrolytes they consume, putting them at higher risk for dehydration.

Many common medications including steroids, diuretics, and antidepressants affect the renin-angiotensin-aldosterone system which controls body water, further complicating the ability to maintain water balance.¹

These medications, often prescribed to elderly patients, increase the importance of proper hydration. 

Approaches to Hydration

Physiologic mechanisms in the elderly present a barrier to the prevention and treatment of dehydration. Every ounce of fluid counts, but some fluids work better than others for rehydration.

When fluids contain electrolytes, such as sodium and potassium, the electrolytes help the body absorb fluids more efficiently compared to just drinking plain water.

The body has a specific formula of water and electrolytes it prefers for more efficient hydration, not found in water.

Sports drinks might seem like the best choice but in a trial studying the hydration power of different beverages, sports drinks provided no more benefit than plain water, coffee, or juice.⁷

What did work best for hydration in this study? Oral rehydration solutions (ORS) and milk. These beverages have the highest tonicity and a beverage hydration index (BHI), which helps to move fluids into the cells for hydration because they contain more electrolytes than other drinks.⁷

Although this particular study did use younger subjects, the average age was 25, it appears that higher tonicity drinks, such as an ORS and milk, may be closer to the body’s ideal rehydration fluid.

While all fluids can help prevent dehydration, higher-tonicity beverages are closest to the body’s ideal drink and provide the patient with greater benefit per ounce.

It is recommended that elderly men consume 13 cups (3 L) of fluid daily and elderly women consume 9 cups (2.1 L) of fluid daily to recoup water losses and stave off dehydration.³

But this recommendation for daily intake includes fluid that is consumed though food. ESPEN recommends that older women be offered at least 7 cups (1.6 L) and men be offered 8.5 cups (2.0 L) of beverages per day.⁸

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