University Of São Paulo Research States Drinking More Water Is Important To Manage Dehydration

The human body is composed of about 60% to 70% water and, therefore, it is essential for maintaining good health. However, the amount that should be ingested still leaves some doubts.

“Because it is so critical to life, there are physiological processes that strictly control the balance of salt and water in the body. Simply put, in order to maintain the amount of water in our body, it is necessary to replenish losses”, comments Professor Eduardo Barbosa Coelho, from the area of ​​Nephrology at the Department of Internal Medicine at the Faculty of Medicine of Ribeirão Preto at USP.

Importance
As stated, water is a huge part of the human body’s makeup. But, in a practical way, what is its real importance? For the organism to keep functioning, biochemical reactions need water and are fundamental: from the exchange of CO 2 for O 2from breathing to digestion. “It transports nutrients and oxygen through the bloodstream, maintains the correct concentration for maintaining electrolyte and acid-base balance, regulates body temperature, maintains cellular structure, including cell membrane and the structure of proteins and nucleic acids, and is vital for the excretion of toxic substances through urine and feces. Water is so critical to life that if you lose more than 4% of your total body water symptoms of dehydration will set in, and if you lose more than 15% it can be fatal,” explains Coelho.

The amount

Coelho says that replacing lost water is necessary, but he also explains how this loss occurs: “Our cells, in the process of cellular respiration, convert nutrients and oxygen that arrive through the bloodstream into carbon dioxide ( CO 2 ) and water. Thus, an adult weighing about 70 kg ‘manufactures’ approximately 700 mL of water per day. Water losses occur in three ways: one part corresponds to the production of secretions (saliva, gastric juice and sweat, for example), the other part is eliminated in breathing and a last part is present in urine and feces”.

A study published by Science points out that the volume for daily consumption is determined by several factors such as sex, age, physical aspects, air humidity, temperature and even the HDI (Human Development Index). Thus, there is no ideal amount of water ー like the famous two liters ー, since the influence of multiple points modifies the needs of each individual.

“There is no ‘normal’ or recommended amount to ingest per day. Generally, for an adult on a standard normoproteic diet, about 1 to 1.5 liters of water will be enough to maintain water balance. However, this value will depend on individual metabolism, age, body fat distribution, environmental conditions, physical activity and other factors that affect water loss. There is a widespread idea that drinking water is good for health. As described above, there are physiological mechanisms for maintaining a water balance and if there is a lack of water, thirst will appear”, points out Coelho.

However, even though there is not an ideal volume to be ingested, Professor Roberto Zatz, from the Nephrology discipline at the Department of Internal Medicine at the USP Medical School, states that certain groups should be more attentive to the amount of water: “Some groups tend to be encouraged to maintain a certain level of consumption, generally something close to the famous two liters/day, to increase the urinary flow. Examples are: individuals with a urinary tract infection or with a tendency to develop it: although there is no conclusive evidence, the very reasonable concept has been established that a high urinary flow makes it difficult for bacteria to settle in the urinary tract; another group that can benefit from a higher fluid intake are people with a propensity to form urinary stones ー ‘kidney stones’. In the absence of such conditions,


Certain groups should be more attentive to the amount of water, such as individuals with urinary tract infection – Photo: Freepik
Control
The thirst mechanism is the body’s main alert in the matter of dehydration. The habit of drinking water recurrently is only necessary, from a biological point of view, when there is an indication that the body is starting to become dehydrated, that is, when thirst appears. “We usually already ingest more than enough ー when we eat or drink other types of liquids ー, and if for whatever reason we fail to do so, the thirst mechanism will force us to correct any imbalances. Thirst is a kind of protection network that guarantees that water losses never exceed gains, thus preventing the individual from becoming dehydrated”, adds Zatz.

To control water loss, the kidneys come into play. They are able to modify the urine concentration by changing the amount of free water eliminated. Coelho explains that we can eliminate from 150 ml, in conditions of extreme water loss or lack of intake, to 20 l of urine in situations of abundance of liquids and nutrients.

In addition to these organs, antidiuretic hormone (ADH), also known as vasopressin, also acts in the regulation of urine. Produced in the hypophysis, Coelho comments on the functioning of this hormone: “When the concentration of water in the body decreases, the concentration of electrolytes is concentrated in the blood, increasing its osmolarity. Sensitive cells, osmoreceptors, signal to the pituitary gland, which produces ADH. This hormone acts on the kidneys, increasing water reabsorption and concentrating urine.” The brain, in this process, identifies the blood concentration and thus controls the rest of the body’s water elimination mechanisms.

Effects

Roberto Zatz – Photo: Reproduction/YouTube (Hospital de Base SJRP)
It is very difficult for excess water consumption to be dangerous, however, there are some specific circumstances that can lead to this: “The kidneys have a great capacity to eliminate excess water, which allows a maximum intake of more than 15 liters per day. This means that, in general, drinking more fluids than necessary does not cause major problems (after all, hardly anyone wants or manages to drink 15 liters of water ー equivalent to 60 glasses or a glass every 15 minutes in a single day). However, there are some situations of water intoxication, a kind of ‘water overdose’. This condition can result from drinking more than 15 liters per day or drinking so quickly, for example, five liters in half an hour, that there is no time for the kidneys to eliminate the excess.

Zatz also adds that there are also risk groups, such as some cancers, which abnormally produce a hormone that hinders the excretion of water by the kidneys, with water intoxication being one of the probable first manifestations of the disease. Chronic kidney disease , also known as chronic kidney failure, is a condition in which the kidneys slowly lose, either due to hypertension, diabetes or inflammatory processes in most cases. In advanced stages, the ability to eliminate excess water is compromised. However, as said, this excess concerns only abnormal amounts of water or when there is a disease that involves it; water remains essential for maintaining health.

Age
The age issue is one of the factors studied by the article, but it is worth mentioning the changes in the body with respect to water, according to age variation. Zatz explains that the elderly have more difficulty saving water when needed: “If the elderly remain alert and active, there are usually no major problems. However, the feeling of thirst isoften blunted in these people, especially if they already have a serious neurological condition, such as previous strokes or dementia. For this reason, it is often necessary to offer them water several times a day, a procedure observed by good caregivers and nursing homes. As for young people, there is no need for any special recommendation. It is evident that individuals who practice sports need to consume more, which can be active (as in the case of street marathons, where water is offered along the route) or motivated by thirst. The same goes for seniors who stay physically active.”

The question of water, when analyzed from a biological point of view, depends on several individual factors that together modify the necessary amount to be ingested. But even if there is no predetermined value, its consumption is important: “Water is the essence of life and, for this reason, our organism is prepared to conserve it. Maintaining health is learning to listen to what your body says. Consume the water you need and avoid excesses. A simple way to tell if you’re drinking too little water is to look at your urine. If it is very orange and in small quantities, it is likely to be concentrated and a break for hydration is recommended”, concludes Coelho.