Essential in the primordial soup is water, a simple molecule, which we all know is the molecule of life. With two atoms of hydrogen (H) and one of oxygen (O), life is, therefore, possible on our planet and perhaps on others as well, since every living thing needs water, be it a plant or animal.

Water is a polar molecule, where the oxygen atom is partially negative and the hydrogen atoms partially positive, making it an excellent solvent, i.e. capable of dissolving one or more other substances.

This is why the role of water in digestive processes is crucial, where it intervenes in what is called hydrolysis reactions (meaning ‘dissolving in water), i.e. reactions, whereby complex molecules ingested with food, are broken down into simpler, more assimilable ones. In the human body, water is the medium in which many chemical reactions take place, in some cases acting as a catalyst, i.e. promoting a chemical reaction without directly participating in it, and in other cases taking part in the reaction itself. A large part of the water is used by our organism in its lubricating action to lubricate moving parts (ocular fluid, cerebrospinal fluid); also, as a beverage, it helps transport ingested substances and aids digestion. Fundamental is the thermoregulatory action of water, which, through the phenomena of evaporation and sweating, allows body temperature to be kept almost constant. Evaporation occurs continuously, and this allows the excess internal energy produced by the combustion of carbohydrates, fats, and proteins to be eliminated; while in the presence of high ambient temperatures or intense physical exertion, the body contains the rise in body temperature through sweating. Water in the human body is not present in a fixed percentage, depending on age and gender, as well as other constitutional aspects such as the ratio of muscle mass to fat mass. The elderly, due to a series of physiological changes that occur with advancing age, have a lower amount of water in the body and a higher risk of dehydration. In women, of the same age, the percentage of water is lower because the percentage of adipose tissue, which is poor in water, is higher.