Water plays many important roles within the body. Water is the major part of most of the body’s cells (except for fat cells) and it also cushions and lubricates the brain and the joints. It transports nutrients and carries waste away from the body cells. It also helps regulate body temperature by redistributing heat from active tissues to the skin and cooling the body through perspiration.
Water is the main constituent of the human body: it is normally about 60% of body weight in adult males, and is slightly lower, about 50-55%, in females due to their higher proportion of body fat. The muscles and the brain are about 75% water, the blood and the kidneys are about 81%, the liver is about 71%, the bones are about 22% and adipose tissue is about 20%.
Most of the water in the body is found within the cells of the body (about two thirds is in the intracellular space), and the rest is found in the extracellular space, which consists of the spaces between cells (the interstitial space) and the blood plasma.
Total body hydration and the balance between input and output of water are under homeostatic control by mechanisms which modify excretory pathways and stimulate intake (thirst).
The body requires water to survive and function properly. Humans cannot live without drinking for more than a few days – depending on weather, activity levels and other factors – whereas other nutrients may be neglected for weeks or months. Although commonly it is treated rather trivially, no other nutrient is more essential or is needed in such large amounts.
Good hydration is essential for health and wellness. Every cell in the human body requires water. Hydration is central to the most basic physiological functions such as regulating blood pressure and body temperature, hydration and digestion.
Some of the most remarkable benefits of hydration are listed below:
Adequate hydration is important for proper functioning of the brain. When we are well hydrated, brain cells are better supplied with fresh, oxygen-laden blood, and the brain remains alert. Mild dehydration, a 1% to 2% loss in body weight, can impair the ability to concentrate. Loss of more than 2% body weight due to dehydration can affect the brain’s processing abilities and impair short-term memory.
Hydration in the body is important for transporting carbohydrates, vitamins, minerals and other important nutrients and oxygen to the cells. The cells then produce energy for the body to function. Furthermore, hydration facilitates disposal of the waste products of metabolism, enabling the right cellular chemical function.
- Digestive Tract
Hydration plays an important role in the digestion of food and the absorption of nutrients from the digestive tract. Water is required to dissolve nutrients so that they may be absorbed into the bloodstream and delivered to the cells. Insufficient hydration will slow the digestive process and chronic poor hydration can lead to constipation.
Fluids are important for healthy heart function and the correct regulation of water balance is essential to keep blood pressure within the healthy range. Dehydration decreases cardiac output which may lead to increases in heart rate and a fall in blood pressure. The circulatory system delivers a constant supply of oxygen to the brain, muscles and to all other tissues.
An adequate water intake is essential to keep the kidneys working well, helping them to remove waste products and excess nutrients mainly via urine. The kidneys regulate the body’s water levels by increasing or decreasing the flow of urine. The kidneys also work to control normal levels of sodium and other electrolytes. A well-hydrated healthy person’s kidneys filter approximately 180 litres of water each day: clearly most of this has to be reabsorbed to prevent excessive losses from the body.
- Muscles and Joints
Water acts as a lubricant for muscles and joints; it helps cushion joints and keeps muscles working properly. Muscles and joints, in addition to the bones, are necessary for us to stand, sit, move and carry out all daily activities. Approximately 70 to 75 percent of the muscle is made up of water. Maintaining the right water balance is essential for optimum muscle function.
The skin constitutes a defence against pathogenic agents and contributes to preventing the development of infectious and allergic processes. Some people believe that good hydration helps to moisten body tissues and preserve the skin’s elasticity, softness and colouring though this has not been researched adequately.
The body water has an important role as a thermoregulator, regulating the overall body temperature by helping dissipate heat. If the body becomes too hot, water is lost through sweat and the evaporation of this sweat from the skin surface removes heat from the body. Sweating is the most effective way that the body prevents itself from overheating.