Which nutrient contains no vitamins, no calories, no protein, and no fat, is odourless, colourless, tasteless and yet, is essential to human life?
If you answered “air”, you are half right.
In the human diet, though, the answer is “water”, our fourth macronutrient.
In fact, water makes up about 60% to 70% of the body!
Humans can live for days or even weeks without food, but only a few days without water.
The food we eat and the beverages we drink give us the water our bodies need to function properly.
It is the body’s most important nutrient, needed in the greatest amount.
Every cell in our body needs water to carry out a variety of essential functions.
Some of these functions include: transportation of nutrients and oxygen to cells and carrying away waste, lubricate joints and cushioning tissues and organs, and particularly in many normal chemical reactions.
Water is also used in the digestion and absorption of our food, and helps keep our stools soft to minimize constipation.
In addition, our body’s internal temperature regulation depends on water.
After we sweat, heat is loss during the evaporation process to keep us cool. (1)
We can be thankful for many complex processes inside our bodies that keep our water levels balanced.
Water does not have calories, so it rarely appears on charts that illustrate basic nutrient requirements.
But as adults, we must drink water daily in order to keep our body’s store of 45-55 litres of water replenished.
Our thirst mechanism usually signals us when we need water.
If we do not drink enough water, we can become dehydrated and our kidneys and other cells will not function properly.
Going without water can even be fatal, in as few as 2-3 days. (2)
We get water from fruits and vegetables , and some water from food such as bread and meat.
We also get water from juices, soft drinks and milk, but plain water is best for quenching thirst.
If possible, avoid coffee and tea when you feel thirsty – the caffeine causes the kidneys to eliminate, not conserve, body water.
For good health, adults should strive to drink at least 6, and preferably 8, (230 ml) glasses of clean water a day, and more if physically active or working under hot conditions. (3, 4)