Water is the main constituent of the human body and represents about 60% of body weight in adult males and up to 75% in a newborn. The total body water content, the intracellular and extracellular hydration process and the balance between the entry and exit of water in the body are under homeostatic control and are exercised with mechanisms that mainly regulate the excretion and, secondarily, stimulate the intake through the sensation of thirst. Feedback mechanisms that act mainly on the kidney are also able, albeit to a limited extent, to regulate the tonicity of intracellular body fluids.
The European Food Safety Authority ( EFSA ) has ascertained a cause and effect relationship between the daily intake of water and the maintenance of normal physical and cognitive functions. The recognition considers that a loss of body water equal to about 1% is normally compensated within 24 hours and that the absence of such compensation and the further increase in body water loss compromise physical and cognitive functions. It is also certain that water plays a particularly important role in thermoregulation . The increase in body temperature is a consequence of the reduction in sweating and cutaneous blood flow induced by dehydration.
The recognition of EFSA refers to waters that meet the regulatory requirements for natural mineral waters and for water intended for human consumption and is associated with the information for the consumer that the indicated effect is obtained with intake. daily of at least 2.0 liters of water in any form .
How much do you need to drink ?
The amount of water to drink is quite variable depending on the individual, taking into account the living environment, the work and activity regime, the type of diet and lifestyles.
Under normal conditions, self-regulation mechanisms and complex factors that determine the sensation of thirst help the body to take on the right water requirement necessary to compensate for water losses, which continually take place due to sweating, breathing, excretion of urine and faeces . However, some individuals, especially children and the elderly, are more prone to dehydration also because they demonstrate a reduction in perception in the sensation of thirst and in the natural urge to drink, with the risk of not adequately and promptly balancing water losses. For this reason, it is necessary to indulge in all cases the sense of thirst by tending to anticipate it, or, in any case, to guarantee the body a regular and adequate water intake to keep the water balance constantly balanced and prevent risks of dehydration. Dehydration, caused by an intake of less fluids than the loss of water, also has serious effects on the body’s activity and physical performance. In the milder forms, thermoregulation is affected and the sensation of thirst is manifested, with the prolongation of the phenomenon cramps, apathy, asthenia and greater irritability appear; more severe forms induce general malaise and even hallucinations up to the risk of onset of heat stroke and lethal effects. The persistent state of dehydration is associated with a significant increase in the risk of many diseases, even serious ones, primarily affecting the kidney.
The European Food Safety Authority (EFSA) scientific panel on dietetic products, nutrition and allergies has recently redefined the dietary reference values for the intakes of various nutrients including ‘water, recommending the amount you need to take to stay healthy depending on your age and gender.
The reference values, which consider the water taken as a whole – both through direct consumption and through food and beverages of all kinds -, in conditions of moderate environmental temperatures and average levels of physical activity, are defined as follows:
puppy up to six months of life: 100 mL/kg per day;
between 6 months and one year: 800-1000 mL/daily;
between 1 and 3 years: 1100-1300 mL/daily,
between 4 and 8 years: 1600 mL/daily;
between 9-13 years: 2100 mL/daily for children and 1900 mL/daily for girls;
teenagers, aduld, elders:
women 2 L/daily
men 2,5 L/daily;
These values are indicative ; in conditions of hot climates and intense physical activities, or other conditions that induce dehydration, the levels of water to be taken can vary significantly (it can also be considered more than double the values indicated). This also occurs in conditions of stress and gastrointestinal disorders that cause vomiting and diarrhea, such as infant’s diarrhea.