In our information-saturated world, we seem to learn about a new fad diet almost every week. One day eating too much fat is bad for you and the next day, carbs are the problem. But the most essential nutrient is often ignored: Water
Life began in the oceans and water is so crucial for the chemistry of life that even terrestrial life like us carries water with us onto the land. Our bodies are made of 55-60% water and this is because the vital functions that keep us alive require water, from transporting oxygen and nutrients to our cells, to helping us digest our food, lubricate our joints, and maintain an adequate electrolyte balance, so our kidneys, heart and every organ can work optimally. However, our bodies can only produce about 8% of the water we need, which means that 92% must be ingested through foods and beverages. Additionally, we lose on average 3L of water every day through sweat, breathing, urine and bowel movements so we need to constantly replenish it.
Authorities in different parts of the world have used different methods to provide guidelines on the optimal daily intake of water for different age and gender groups based on indirect methods and generalizations. The general recommendations for Adequate Intake (AI) from European and American health organizations are in the range of 2000 to 2700 ml/day (68 to 91 fl oz/day) for adult women and 2500 to 3700 ml/day (85 to 125 fl oz/day) for adult males. But the reality is that there are no completely adequate biomarkers to measure hydration status at the population level and our individual water needs will vary on a daily basis depending on the environmental conditions, diet and physical activity, the amount of sugary beverages we consume, etc. In extremely hot weather, we might lose more water through sweat, whereas extreme cold might make us urinate more. Our diet can also be an important source of fluids, with fruits and vegetables containing the highest amount of water. This Hydration Calculator takes into account different factors to help you estimate if your water intake is adequate.
Nevertheless, a large number of people in the United States and around the world are falling significantly below the recommended daily intake of water. There are many factors influencing this, including the lack of access to clean, potable water in vast areas of the world and parts of the United States. But even in areas where water is readily available, it’s become very common to substitute water for sugary beverages (sodas, fruit juices, energy drinks), coffee, tea and alcohol, all of which can act as diuretics. As a consequence, many people suffer symptoms of mild dehydration daily without even realizing that all they need to do is drink more water. Some of the symptoms of dehydration include brain fog, mood swings, dizziness, fatigue, sleepiness, lack of energy, headaches and constipation – sound familiar?
In fact, it has been found that a decrease of only 1-2% of body water is enough to impair cognitive performance and mood, and some of the effects of dehydration in mood and cognitive functioning can persist even after replenishing the fluid deficit. On the other hand, euhydration can improve visual attentiveness, short-term memory, mood, concentration, and reaction time. For these reasons, it is especially crucial to make sure children and youth have access to plenty of drinking water at schools.
In spite of the large amount of evidence on the need of drinking pure water, most official guidelines are based on total fluid intake from “any beverage”, including those with a high sugar or fructose content (soda, fruit juice, energy drinks). Aside from the effects these beverages have on increasing the risk of obesity, diabetes and tooth decay, the extremely high sugar content in them, spike the concentration of sugar in the blood and trigger cells to release water into the bloodstream in order to maintain the very delicate balance of fluids inside and outside cells. This water loss in cells and organs will exacerbate, rather than overcome dehydration and in conditions of recurrent dehydration, sugary drinks can have more severe and irreversible consequences such as chronic kidney disease. High blood glucose levels induced by sugary drinks will also increase urination, which in turn, exacerbates dehydration.
But in addition to water, we also lose a fair amount of sodium and other minerals known as electrolytes every day. Maintaining the proper balance of electrolytes in the body is crucial for multiple physiological processes and some methods of water filtration that remove contaminants tend to also rid the water of minerals. If you are drinking bottled or filtered water, make sure to add one or two drops of trace minerals or a pinch of sea salt per glass of water. You will notice that a small amount of electrolytes will make your water more palatable. Other ways of enhancing the flavor of your water without the need for sugar is adding a few drops of lemon or infusing the water overnight in the refrigerator with slices of lemon, cucumber or aromatic herbs like mint or basil.
Next time you feel tired, sleepy, brain-foggy, or get a headache, think about when was the last time you drank water. You could be dehydrated.
Diuretic: tending to increase the excretion of urine
Euhydration: Normal level of hydration; absence of hyperhydration or dehydration.
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Riebl, S.K., Davy, B.M. 2013. The Hydration Equation: Update on Water Balance and Cognitive Performance. ACSMs Health Fit J. 17(6): 21-28. doi: 10.1249/FIT.0b013e3182a9570f