Hydration refers to water and the amount you have in your body at any one time.

Hydration is part of a healthy medicine approach to life. Not enough water and many crucial processes start to breakdown. Too much water can also be a problem.

Awareness of the need for hydration has increased over the years. Witness how many people you see walking around the streets with the ubiquitous bottle of water.

What are the facts? How much do you need, can l have too much water, does coffee count, are there special needs for water at different stages of our life?

Interesting

Water is the most abundant component of our body. For most people around 60% of your body weight is due to water. This is why early rapid decreases in weight can occur when a person undergoes most styles of diet. In other words most of the change was due to a loss of water.

Why we need water

It is common knowledge that to practice healthy medicine we need water. But if you ask people precisely why we need water the answers get a little hazy. “We just need it don’t we”?

Well yes we do need it. Let’s understand in more concrete terms what role the water in our body plays.

1. Temperature Control

The healthy human body maintains an internal core temperature of around 37° Celsius. This may vary a little between individuals and for a variety of factors. The main reason for the temperature to be constant is that cellular processes operate most efficiently 37°. If the temperature varies by much, either hotter or colder, then disruption to body processes will occur.

A body moves through the burning of fuel such as glycogen and fat to make muscles contract. This fuel metabolism has heat as a by-product that makes contribution to the core temperature. If the heating causes your core temperature to rise then this needs to be controlled or risk damage to your system.

Heat can be dispersed a number of ways. Your skins capillaries can dilate and release heat to the environment. You can increase your respiration (breathing) rate and lose heat through the air your body has warmed up in your lungs. The method that accounts for at least 75% of necessary heat loss is sweating. It is the evaporation of the sweat that cools us down. Evaporation is known as an endothermic process. It requires energy to work. The energy is provided by the heat in your system and in the sweat. As it evaporates it takes heat energy with it and you feel cooler.

This is why on a humid day we can feel very hot. So much water saturation in the air means it is very difficult for the sweat to evaporate and become a gas in the air. No evaporation means no cooling.

2. The Blood

Blood is the fluid in which dissolved gases (especially oxygen and carbon dioxide), nutrients, hormones and waste products are transported. It acts within the circulatory system to meet the cellular demands of every cell in our body

Blood is composed of straw-colored liquid called plasma which contains cells. There are many types of cells to be found in blood. The most common are:

Approximately 90% of plasma itself is water. Plasma typically accounts for 55% by volume of blood and of the remaining 45% the greatest contribution is from the red blood cells.

If we are dehydrated, this percentage of plasma drops. As it drops the viscosity of our blood increases and so our blood gets harder to push around our circulatory system. This can create serious health issues among people of any age but particularly in people with blood vessel narrowing.

Of note is the fact that highly trained athletes in cycling’s Tour de France are barred from competition if their plasma percentage drops below 50%. Over the years quite a few of the cyclists have died during their sleep, presumably with a decreased heart rate and with more viscous blood combining with disastrous effect.

3. The Cells

The percentage water composition within a cell can vary depending upon the type of cell we are referring to. In general terms though the water content of each cell is around 80%.

The properties of water are unique and explain why it is so important to the cells. Water is a biological solvent capable of dissolving many things through its amazing chemical composition. Due to water the bloods contents can get to the cell, the cell can complete its function and the blood can remove the waste away.

Without the right amount of water there would be no cells or cell function. Drink up!

4. The muscles and joints

Water has its role to play here.

In the joint there is not a lot of water compared to other parts but none-the-less it is here. It acts as a cushion in the fascia and cartilage that both line and separate the opposing bones in a joint.

The muscle cells are made of around 70% water. In and around muscle cells are fat cells which have a lot of water in them too. Bodybuilders will typically dehydrate themselves before a competition to remove as much of this water as possible to create a more lean figure.

Muscle cells have been known to breakdown in extreme dehydration such as in endurance events with high temperatures. This condition is colloquially known as muscle meltdown (rhabdomyolysis) can cause serious damage due to the release of muscle cell components that can destroy kidney cells. If exercising it is important to be hydrated and continue to hydrate if the activity is prolonged. If it’s too hot, stop.

5. Gastro-intestinal System

Water is all through your gastro-intestinal system.

It is released in your mouth from the salivary glands to help lubricate and pre-digest food before it slides down the oesophagus into your stomach. The enzymes that are delivered to your digestive system are dissolved in water and then the nutrients resulting are taken with water into the circulatory system for transport to the cells.

Some water remains in your digestive system to assist in the removal of waste. Constipation can occur if there is not enough water in the lower bowel.

6. Kidneys

The kidneys play a vital role in regulating the body’s fluid volume through a balance of excretion and reabsorption of water and electrolytes. To get this right it has to filter around 180 litres of fluid each day.

If it does not have the correct intake of water it can have a hard time doing its job.

Your fluid balance has a large influence on blood pressure control. You need to treat your kidneys right if you want to avoid high blood pressure.

Dehydration

Most people maintain a reasonable fluid balance through normal drinking behaviors such as with meals and at breaks at home or at work.

It is important to be aware that some groups of people need to pay some more attention to their fluid intake. This includes the young, the old, those with physical vocations, people active in hot environments and those who exercise for long periods.

How do l know l am becoming dehydrated?

In many cases you may not know. One of the problems with dehydration is that the symptoms can come up on you with little warning, maybe a little dizziness and disorientation, maybe just a headache or frustration with a task you can’t get right.

This is why we all have to be alert both to ourselves and those around us who may be developing signs and symptoms of dehydration.

What may happen:

Some symptoms by percentage body weight water loss:

What do you do to prevent dehydration?

What if you have become dehydrated?

Some hydration guidelines

There is good news out there for most people. You don’t have to walk around with a bottle in your hand drinking water all day. In addition the recent evidence is probably going to challenge a few commonly held beliefs you have about what is good for you.

How do l meet my hydration needs?

Some common misconceptions

Caffeine as a chemical is a stimulant and also has a diuretic effect. This means that it acts on your kidneys to excrete water. This is not news.

What is lost in the facts is that the diuretic effect is minimal in moderate caffeine consumers of 2-3 cups of brewed coffee per day. In fact in heavy users of caffeine of more than 6 cups per day the diuretic effect is still not so bad. It appears they develop of tolerance of caffeine and its diuretic effect.

So, where do we stand on caffeine? When we consume a caffeinated drink the body definitely retains some of the fluid content. Thus it comes under notice as a contribution to your hydration needs. Like most things in life the key is moderation. If you enjoy caffeinated drinks then don’t stop drinking them on the basis of your dehydration fears unless you know that your consumption of them is excessive.

If you do decide to cut back your daily consumption of caffeinated drinks then be aware that you are reducing your daily fluid intake. You will need to replace this with some other form of fluid intake.

So how much do l need each day?

The recommended actual consumption of fluid (not in your food) varies depending upon your exercise levels and type of environment you live in. However, there are recommended numbers of cups (240ml) of fluid (all beverages except alcohol) you should consume per day.

1-3 years; 4
4-8 years; 5
9-13 years; male 8, female7
14-18 years; male 11, female 8
19-70 years; male 13, female 9

Special hydration needs

Children

Children overheat quicker than adults through a decreased ability to sweat efficiently. They can quickly dehydrate due to activity and warm weather. Be aware of signs such as: