by Alexia Svoulou
The water we drink is as essential as the oxygen we breathe. We are made of water, a large part of our body consists of water and proper hydration in winter and summer is a prerequisite for health and wellbeing.
- The “thirst bell” rings late
- Hydration is important even during the season of infections
- How water deficiency affects vital organs
- What happens in the brain
- How digestion is affected
- The heart is a pump
- The kidneys are the body’s filter
- The lubricating properties of water
- Hydration of the skin – a health and beauty issue
- The complications of prolonged dehydration
- Heatstroke
- Water, infusions and soups
To stay healthy we must drink water every day. Water is a fundamental component of the human body and about 60 % of an adult’s body weight is water. Most of the body’s water is intracellular, with the remainder extracellular. Naturally, not all organs and tissues contain the same water percentage. “Champions” are blood and kidneys with 81 % water content, followed by the brain and muscles at 75 %. The liver comes next with 71 %, while bones contain 22 % and adipose tissue 20 %. The body needs water to survive and function normally, which is why humans cannot live without water for more than a few days, whereas they can survive without food for much longer periods.
The “thirst bell” rings late
The importance of proper hydration is usually highlighted in the summer months when water loss is increased by heat and sweating. Dehydration triggers the feeling of thirst that tells us to drink, but it is a common secret that when we become aware of thirst, dehydration has already reached 10 % or even 20 %. For infants, toddlers, children and the elderly the dehydration percentage can be even higher because the mechanism that awakens the feeling of thirst does not “activate” promptly.
All of this contributes to us forgetting to drink adequate amounts of water not only in summer but throughout the year, as noted by clinical dietitian‑nutritionist Sofia Eleftheriou.
Hydration is important even during the season of infections
Now let’s look at winter, when hydration does not seem to be a priority – and that is wrong. In fact, during flu season, the respiratory coronavirus, enteric viruses and other viruses and bacteria that threaten us, proper hydration is especially important when we are ill and have a fever. Lack of water intake can raise the fever further, so besides antipyretics we must also drink water. In the winter months, schools, nurseries and holiday parties see a surge in gastroenteritis, which causes even greater fluid and electrolyte losses through repeated vomiting or diarrhoea. In those cases we must be even more careful, offering water and infusions or even electrolyte sachets if needed, which the patient consumes slowly in small sips. Body water plays a very important role as a regulator of temperature. If the body overheats from fever (or heatstroke) water, via sweating, reduces the temperature.
Loss of water from the body equivalent to 1 % of body weight can be replenished within 24 hours. Elevated dehydration levels above 1 % gradually reduce athletic performance and thermoregulation. Losses above 4 % cause a serious decline in performance together with concentration difficulties, headaches, irritability and drowsiness, while loss greater than 10 % can be fatal.
How water deficiency affects vital organs
Body hydration is crucial for the transport of carbohydrates, vitamins, minerals and other nutrients and oxygen to the structural unit of our organism – the cells. It also influences the energy produced by the mitochondria of the cells for bodily functions and the balanced removal of metabolic products (free radicals and other “waste”), which determine smooth cellular biochemical activity and are directly affected by the water content of the cells.
What happens in the brain
Adequate hydration of the brain is vital for its smooth operation because it ensures proper oxygenation. Mild dehydration of 1 %–2 % of body weight can impair concentration ability. Loss of more than 2 % of body weight due to dehydration can affect the brain’s functional capacities as well as short‑term memory.
How digestion is affected
Hydration plays a very important role in the digestion of food and in the absorption of nutrients from the gastrointestinal tract. Water is essential for nutrients to dissolve so that they can be transported to the cells via the bloodstream. Insufficient hydration slows the digestive process and chronic inadequate hydration can lead to constipation.
The heart is a pump
Fluids are important for the normal functioning of the heart and proper regulation of water balance is necessary to keep blood pressure at normal levels. It should be remembered at this point that the heart is a continuously operating pump which, in fact, works independently of our will. Dehydration reduces cardiac output, which can lead to an increased heart rate and a drop in blood pressure, affecting the function of the brain, muscles and other tissues. On the other hand, conditions such as heart failure do not allow the patient to drink a large amount of water at once.
The kidneys – the body's filter
Adequate water intake is vital for the normal function of the kidneys, helping them to remove metabolic waste and excess nutrients mainly via the urine. The kidneys also regulate the physiological levels of sodium and other electrolytes. The kidneys of a well‑hydrated person filter about 180 litres of water each day, which is, of course, re‑absorbed to prevent excessive fluid loss from the body.
The lubricating properties of water
Water acts as a lubricant for muscles and joints, coating the joints and allowing smooth muscle function. Water makes up 70–75 % of muscle, so maintaining proper water balance is essential for optimal muscle performance. Water also moistens the eyes through tears, helping to dislodge foreign bodies.
Health and beauty issue – skin hydration
Good hydration supports the proper moisture of the body's tissues and the maintenance of skin elasticity. Well‑hydrated skin is more resistant to infections and allergic reactions, and the component that retains water in the skin is naturally produced hyaluronic acid. However, as the years pass the body no longer produces sufficient hyaluronic acid, which is why it is found as a key ingredient in cosmetics. To keep our skin properly hydrated we also need to drink water daily and look after it with moisturizing cosmetics. Using cosmetics alone does not achieve anything because adequate hydration starts from within.
Complications of prolonged dehydration
A short‑term shortage of fluids (water mainly) for one or two days does not cause any problem beyond fatigue and possibly a headache, usually due to stress, insufficient water intake, or both. If dehydration becomes prolonged, complications arise. For example, the risk of infections increases, particularly of the urinary tract (UTIs, etc.). The kidneys and other vital organs, which receive reduced blood flow, begin to under‑function. Usually the resulting renal insufficiency is reversible if it is caused by dehydration. Reduced blood supply to the brain can cause confusion, impaired cognitive function, reduced coordination and headache.
Mild dehydration can cause symptoms such as thirst, headache, weakness, dizziness, fatigue and generally makes a person feel tired and sluggish. Also, when urinating we notice that the urine colour is darker.
Symptoms of moderate dehydration may include dry mouth, little or no urine, numbness, tachycardia and reduced skin elasticity. It is characteristic that in infections with high fever or viral gastroenteritis or food‑borne gastroenteritis, if we pinch the skin on the forearm between two fingers, the skin becomes very taut and appears very thin, like paper.
Heatstroke
Severe dehydration is characterised by unquenchable thirst, no urine, rapid breathing, impaired cognitive function, cold skin and requires urgent medical attention, as it is life‑threatening. Such cases occur with very high fever and heatstroke, and at this point we must remember that animals are far more susceptible to heatstroke than humans. Dogs and cats have no sweat glands and cannot “cool down” by perspiration, making them especially vulnerable.
Water, infusions and soups
Therefore, for all the above reasons we must drink plenty of water each day. Keep a bottle of water at the office, pour water into your glass to maintain health and well‑being, clarity and good spirits. Hydration also includes infusions and soups, fruits and vegetables that have a very high water content, such as cucumbers (over 90%). The contribution of drinks and infusions to the body’s hydration cannot be disputed, but we should not rely solely on tea or coffee, as the caffeine in both infusions is diuretic and can cause dehydration, especially when over‑consumed. Alcohol is also diuretic and causes dehydration. Consequently, to enjoy health and well‑being we must drink abundant water every day.
