The human body consists mainly of water. Water is a solvent and transport medium and is necessary for all metabolic processes in the body. The water balance is regulated both by the intake of liquid from the diet and by proper water consumption. Thirst sensation occurs as a result of fluid loss through sweat, urine or after a salty meal.
A lack of water intake may lead to circulatory problems, concentration difficulties, confusion, or constipation. If the thirst is missing as a signal generator, reminders can be helpful. For example, you can check the fluid intake with a tally sheet or you can put eight empty glasses of 0,2 litres on a tray in the morning, which should be filled and drunk until evening.
If the water balance is not right, the body usually sends thirst signals: The lips, mouth and throat become dry. Adequate hydration can be observed by the colour the urine, the colourless the urine is, the better the liquid supply.
Adults should drink 1,5l daily at least.
In excessive sweating (sports, heat, heavy work), the required daily liquid amount can go up to much more than 3 litres. During reduced food intake we should drink much more, because the supplied fluid is missing from the diet. We also need more liquid on high-dietary fibre food.
The drink of choice is water, the best and most controlled food and it is calorie free.
In a balanced varied diet fruit juices are also useful. They should be diluted with water in the ratio 1:3, because of their fructose content. Especially orange juice and currant juices contain plenty of vitamin C. In all the intense red and yellow juices (natural colour, not of added dye) a lot of healthy secondary metabolites are contained. The same is true for tomatoes – and other vegetable juices, which are also low in calories (caution: often a lot of added salt). Unsweetened fruit – and herbal teas are very good thirst quenchers as well.
By the way, milk does not count as a drink to quench your thirst, but is a nutrient-rich food!
A caffeine beverage, such as coffee, black, green – and mate tea, cola drinks and energy drinks are stimulating. The caffeine that is also present in cocoa and chocolate in small quantities, affects the central nervous system. The pulse rises, because the heart is stimulated to greater pumping capacity, the adrenal glands pour out more of the hormone nor-adrenaline. The blood pressure is temporarily increased slightly. The whole metabolism gets going and the caloric basal metabolic increases. Organs are better supplied with blood, among other things, the function of the kidneys are stimulated and therefore the urinary excretion as well, similarly, the gastric secretion. The bronchi dilate, breathing accelerates. Physical and mental endurance are improved, as the reaction rate, concentration and the ability to deduce. Caffeine promotes the formation of serotonin, a mood-enhancing neurotransmitter. But beware: Caffeine is a very contrasting substance. All positive effects can be reversed from excessive caffeine consumption. About 4 cups of coffee or 1 litre black tea during the day is acceptable for a healthy adult person.
Alcohol can well have a healthy effect. For example, red wine contains flavonoids and phenolic acids which lower the cholesterol in the blood and inhibit the formation of blood clots causing heart attacks. The amount of alcohol intake is, however, of particular importance. Too much of has exactly the opposite effect: it promotes high blood pressure, liver, pancreas and stomach disorders and the risk of cancer increases. It is recommended that no more than ¼ litre of wine per day or 1 to 2 half pints of beer or spirits should be drunk.
Alcohol has quite a high amount of calories and should be therefore taken carefully.