On average, humans should be drinking two litres of water a day. — PIXABAY/Pexels
As people get older, the likelihood of dehydration increases significantly. In the USA, studies have indicated that around 68% of people over the age of 70 suffer some degree of dehydration, a condition which can lead to adverse health outcomes in older people.
Examples of such health risks include falls, bone fractures, heart disease, confusion, delirium, heat stress, constipation, kidney failure, pressure ulcers, inferior recovery from internal/external wounds, infections, seizures, increased drug toxicity, and an overall reduction in the quality of life. A small sample of 103 people aged 65 or over admitted to hospital in the USA found that 40% of them were dehydrated on admission, although it is unclear if the hospital admissions were all caused by dehydration.
Despite dehydration being a common word, few would know that probably the most objective measurement of the condition is done by assessing serum osmolality, a measure of the osmotic pressure of blood serum, which in turn reflects the number of dissolved particles (e.g., electrolytes, or minerals such as sodium, calcium and potassium) per kilo of serum.
A higher count of particles in blood serum indicates dehydration, so a particle density reading of 295-300 mOsmol/kg signals impending dehydration and anything over 300 mOsmol/kg is a sign of actual dehydration. Furthermore, the state of dehydration can be sub-classified into: (a) water-loss dehydration, due to a deficit of water, which may have resulted from hypernatraemia (high blood sodium levels), or hyponatraemia (low blood sodium levels) in the presence of hyperglycaemia (high blood glucose); or (b) salt-loss dehydration, due to a deficiency of both salt and water.
As people get older, the likelihood of dehydrated increases severely compared to when a person is younger. — RON LACH/Pexels
Dehydration can occur at any point in life, and some causes are diarrhoea, exudation (weeping fluids from burns or other raw areas), increased sweating from fevers, polyuria (frequent urination), vomiting, and/or inadequate fluid intake. The resultant hypovolaemia (decrease in blood plasma volume due to loss of water) raises serum osmolality causing electrolyte balance disruption and dehydration. Yet another common cause of dehydration is the consumption of alcohol – and there is more about this later on.
With older people, the risks of dehydration are higher, not just for the factors mentioned above, but because age diminishes the sensation of thirst, hence it is not adequate for older people to rely on thirst to ensure the consumption of water/fluids – they often just do not feel thirsty even when they should.
Additionally, the ability to regulate sodium in blood serum decreases as kidney function declines in older people, and this problem is often exacerbated by medications which induce changes in serum osmolality. Older bodies also tend to retain less fluids resulting in lower blood volumes, especially for people who are less physically active. Finally, older people are often less mobile, which can limit their ability to access water.
The bigger picture
With global warming, the risks of dehydration are compounded due to changing weather patterns and increased heat. As such, aggravated dehydration risks do not apply just for older people. Hotter weather patterns such as heatwaves experienced in recent years, simply places more and more people at risk of dehydration.
The loss of fresh water sources due to vanishing glaciers/lakes/rivers, unseasonal droughts, sea level rises, plus human pollution may mean that drinking quality water can become an increasingly rare and expensive resource in the not too distant future.
Despite the fact that water covers 71% of our planet’s surface, only 3% of the water on Earth is fresh water. Out of that 3%, over 2.5% is unavailable for human usage, because of pollution, or being locked/captured in glaciers, polar ice caps, the atmosphere or soil.
Hence, just under 0.5% of the Earth’s water is available fresh water, though even this amount needs to be treated before it is safe from pathogens which may infect humans drinking such water. Even now, there is much more crude petroleum still under the Earth than drinking water at any point in time.
Therefore, access to drinking water is not always a given for many people, as witnessed by unseasonal, extensive, widespread droughts around the world resulting in distressed poor people drinking from unsanitary sources of water. Sadly, these acts of water desperation very often result in crippling water-borne diseases, resulting in poor health or even death, and still would not have prevented dehydration.
Symptoms of dehydration
At a personal level, it is not always necessary to assess serum osmolality to determine dehydration. There are some symptoms which can indicate the condition, and one should watch out for the following signs (or combinations of signs) in oneself and/or especially in older relatives:
After drinking alcohol, it is highly advisable to drink a lot of water. — ELINA SAZONOVA/Pexels
• dark yellow, strong-smelling urine
• urinating less often than usual
• dizziness or lightheadedness
• constant sensation of tiredness
• dry mouth, lips and tongue
• sunken eyes
• persistent thirst
If one or more of the above signs appear, then a suggestion would be to drink some water immediately. I was guilty of ignoring such signs during a long hike in the sun last summer after a very boozy lunch, and it was difficult to get back home, especially as I had forgotten to pack my water bottle on the walk.
On average, humans should consume about two litres of water a day. This may be harder to achieve than one might think, and a common reason is that drinks with alcohol can dehydrate the body, as explained below. In such situations, the body can do with another litre or more of water to help with the effects of alcohol.
In any case, the recommendation is to drink eight glasses or more of water every day, and to spread the consumption of water over the day. In my case, I have a litre bottle of water beside my desk, which I refill and drink from every day, to top up the water at meals.
A (technical) aside about alcohol
At this point, it may be helpful to understand why one needs to drink more water after consuming alcohol (or ethanol, which is the proper name).
Ethanol is absorbed quite rapidly from the stomach, the duodenum and the small intestine where it then hits the blood stream. Some 2-4% of this ethanol is eliminated via respiration (breathing) and the kidneys. The liver then tries to deal with the balance of blood alcohol – this is done by liver and stomach production of Alcohol Dehydrogenase (ADH), an enzyme which catalyses the oxidation of ethanol into acetaldehyde. This is the good news.
The bad news is that acetaldehyde is actually MORE toxic than ethanol. So another two enzymes, generally grouped as Aldehyde Dehydrogenases (ALDH1 and ALDH2) working together with a complex liver compound called glutathione, are required to oxidise acetaldehyde into harmless acetate (or acetic acid).
Older people tend to retain less fluids, which is precisely why the elderly should drink more water. —JIMMY CHAN/Pexels
A small portion of the acetaldehyde is oxidised by specific liver cells using ALDH1 (a process known as cytosolic oxidation) but the bulk is oxidised using ALDH2 in the “mitochondria” of other liver cells – the mitochondria can be considered the filtration engines of such cells. Glutathione contains a molecule called “cysteine” which targets acetaldehyde and promotes the efficiency of the aldehyde dehydrogenases.
The problem is that there is a rather slow speed limit to the oxidation of acetaldehyde and the more one drinks alcohol, the more acetaldehyde gets into the blood as ADH is significantly more efficient at producing acetaldehyde than the ALDH enzymes are at removing it.
The reason why ingesting water is important when drinking alcohol is because ethanol also suppresses the production of a hormone called vasopressin, which helps the body to retain water. Less vasopressin means the kidneys are overworking to produce more urine by extracting fluids from the blood, thereby causing dehydration. Under the influence of ethanol, urine is produced much faster than ethanol is metabolised, and this then further serves to concentrate the acetaldehyde in the blood, making one feel even worse and possibly craving more alcohol to drink to alleviate the feelings of unpleasantness.
Anyway, apart from making sure one drinks lots of water when consuming alcohol, I can additionally offer two bits of subjective advice regarding drunkenness, based on decades of personal alcohol consumption. Lips are the most sensitive part of the human body, with over 1 million nerve endings and in theory, the effects of acetaldehyde in the blood may be detectable via the lips.
So, the first bit of advice is that one should stop drinking alcohol when the upper lip begins to feel numb. However, it is not often one heed such signs when inebriated, so the second bit of advice is that if the lower lip also starts to feel numb, then it would be sensible and imperative to head home immediately, if it is possible. Hopefully, one’s legs would still be working by then.
The views expressed here are entirely the writer’s own.
