Water is life. How many times have we heard it said, applied to nature, gardens, animals. But water is life for us too, even if we often forget it. Staying hydrated is in fact essential to regulate internal body temperature, support digestion, prevent constipation, purify our body of toxins and bacteria, such as those that accumulate in the bladder, keep joints lubricated and healthy, the skin moisturized and soft, sleep well, be able to concentrate and keep sadness at bay (Source Harvard Medical School, Harvard Health Publishing). Yes, in fact, as scientific studies have shown, even mild dehydration, which causes a loss of 1-3% of body fluids, as happens after physical activity or a sweat, can cause mood changes, poor concentration and the perception of increased difficulty in carrying out activities (Armstrong et al, J Nutr, 2012). So let's see what we can do to avoid dehydration.
How much water to drink
The answer is not unique, in fact it depends. It depends on whether you are taking diuretic drugs or drugs that can increase fluid retention, if you do a lot of sport, if you sweat. Typically, for healthy people, experts recommend about 2 liters of water per day for women and 2.5 liters for men (Nakamura et al, Nutrients, 2020). This amount, however, as mentioned, can vary according to our state of health and our activities. It may be useful to always talk to your doctor who will help evaluate the right water intake based on your needs. For example, studies have found that if you have high blood sugar, you can increase your water intake by one liter by drinking 500 ml of water upon awakening and 500 ml of water before going to sleep, in addition to your normal water intake during the day. This allowed to reduce blood pressure and to protect the kidneys (Nakamura et al, Nutrients, 2020).
Why it is important to drink even when there is no thirst
Our body sends us the signal of thirst in general when dehydration is already present. However, other signs can also be observed, such as dry mouth, headache, great tiredness but also urine that has an amber color (Source Harvard Medical School, Harvard Health Publishing). This is why it is important to prevent the sense of thirst.
Avoid sugary drinks
Many prefer to resort to sugary drinks. However, this only adds calories and inflammation and the thirst increases (Source Harvard Medical School, Harvard Health Publishing).
Bottled water, how to choose it
Tap water is certainly an excellent choice, clearly in countries where it is drinkable. As for bottled water, try to choose it low in sodium. In fact, our diet contains high amounts of sodium and increasing the presence of this mineral can endanger the heart and blood pressure. Then, the dry residue is also important, which are the dissolved solids, such as calcium, potassium, magnesium, phosphorus, selenium, manganese and chloride. If the dry residue is between 500 and 1500 mg per liter then the water, which is classified as mineral water, is fine in summer or when it is very hot and you sweat as it allows you to replenish the lost mineral salts. In fact, these salts contained in water are more easily assimilated than those contained in foods, as minerals in food are linked to other compounds that can reduce their availability, while in water they are found in the form of free substances (Quattrini et al , Clin Cases Miner Bone Metab., 2016). During the year, when there are no particular needs, water with a lower dry residue, below 500 mg per liter, is fine, as in medium-mineral and low-mineral waters.
Feel hungry but thirsty
Also pay attention to the sense of hunger. Often our brain confuses hunger with thirst and therefore, instead of making us feel thirsty, it sends us the signal that we would like to eat. Indeed, studies have shown that only in 2% of cases we are able to drink at the right time without feeling hungry but with a start of an urge to drink (McKiernan et al, Physiol Behav, 2008). In this case, especially on hot days when you sweat, an idea may be to drink a glass of water when you feel hungry between meals, or, even better, a glass of water per hour.
Water also in food
We can also integrate water by eating, choosing foods rich in this precious substance. For example, melon, strawberries, watermelon, lettuce, broccoli, cabbage, celery, spinach and zucchini contain between 90 and 99% water, once cooked (Popkin et al, Nutr Rev, 2010).
Not just water
When we are thirsty, we are often led to choose other drinks, in addition to water, such as tea, black, green or white, coffee and iced tea. It had been hypothesized that, due to the presence of caffeine, these drinks could be diuretic and therefore increase dehydration. Instead, studies have shown that moderate consumption of these drinks is no more diuretic than regular tap water. Juices were also found to be able to improve hydration, having the foresight to choose these drinks without added sugars (Maughan et al, Am J Clin Nutr, 2016). Another possibility is provided by infusions, such as those of chamomile, mint, hibiscus or fruit, which, if unsweetened, provide hydration without increasing the calories ingested (Benelam et al, Nutrition Bulletin, 2010).
