With the water comprising about 60% of the human body and some organs being as much as 80% water, the importance of water for human health and sustaining life is obvious. Hydration levels are not usually a concern for most healthy people who are consuming a balanced diet. However, the type of beverages, quantity and even food are all factors that are important for maintaining and restoring the water level in the body.
What is hydration?
Hydration refers to the water volume in the body. The term is also considered as the process of administering or introducing water into the body, specifically into the cells, tissue spaces and bloodstream. Hydration can therefore be seen as an ongoing process that usually occurs daily and is necessary for life.
For most of us this is done through by drinking water or other beverages. Food also contains water so eating food also forms part of hydration. Normally the body loses water during the course of the day but there is also water intake which should maintain a balance. However, there are instances where a person can become dehydrated and then may need to be rehydrated.
What is dehydration and rehydration?
Dehydration is when there water volume in the body drops too low. Since water movement in the body is largely dependent on the presence of salts (electrolytes), there is usually also an electrolyte deficiency in dehydration. Water and electrolytes are easily lost through excessive sweating, vomiting, diarrhea and excessive urination.
Rehydration is a term to describe restoring the water and similarly the electrolyte levels in the body following dehydration. This can be done orally by drinking water and other beverages or it can be done intravenously (IV) with a drip. Food can also assist with rehydration.
Read more on dehydration.
How much water is enough?
It is commonly recommended that adults drink at least 8 glasses (of at least 8oz or approximately 235ml) of water daily. However, this is an estimate and may not be suitable or necessary for every adult. People who live in hotter environments or those who are more physically active may require more water. Furthermore, most people acquire at least 20% of their daily water intake from food. Some foods may have a higher water content than others which can alter the need for fluid intake in a day.
Despite the recommendation of at least 64 ounces (approximately 1.8 liters), the individual needs of adults may be as much as twice this level in a day. In other words, men may require as much as 125 ounces (approximately 3.5 liters) of water in a day while women may need at least 90 ounces (2.5 liters) daily. Therefore it is difficult to conclusively declare a daily water requirement for all adults, irrespective of age, gender, environmental factors, dietary habits and individual health status.
Too Much or Too Little Water
Although the exact water level needed daily cannot be ascertained, too much water intake may not be as detrimental as too little water intake. The healthy body is able to regulate water levels very effectively. Excess water is excreted through in the kidneys via the urine. If water levels are too low then the kidneys can help to conserve water by reducing urine output.
Since the human body cannot acquire water in any other way than through food or fluids, it is therefore a better option to ‘over’ hydrate rather than ‘under’ hydrate. The kidneys will regulate the water volume in the body. However, there is also a risk of water intoxication if there is excessive water intake. This can be dangerous in people with certain kidney and endocrine diseases as well as if there is insufficient electrolye intake with the water.
Read more about excessive water intake.
How to Hydrate?
It may seem to be simply a matter of drinking water but hydration has many other factors that need to be considered. In a healthy person with a balanced diet, these various other factors may not make a difference to hydration. However, when there are certain underlying diseases or dehydration then hydration and rehydration has to be undertaken with greater care.
Electrolytes (Salts) Are Important
Water alone may not be sufficient, especially when dehydration is present. Various electrolytes like sodium, potassium and magnesium among other salts may also be required for optimal hydration. Often oral rehydrating solutions (ORS) are advisable for treating dehydration rather than water alone. Without these salts, water may not be absorbed from the gut and may even exacerbate “water-losing” processes like diarrhea.
Drink Fluids Throughout The Day
A large intake of water may inadvertently lead to increased urination. The excess water is then passed out within a short period of time if the body does not immediately require this fluid volume. Furthermore fluid intake should increase during periods in the day when it is most needed. This can vary from person to person and in different climates or with different activities.
For example, fluid intake should be higher during the day in hot and humid conditions as dehydration can arise within just 30 minutes in extreme conditions. Alternatively hydration may need to be higher at night if a person is more physically active in the evening. Have a water break every 20 minutes in hot or physically demanding conditions.
Avoid Water-Losing Substances (Diuretics)
Certain substances, particularly some beverages, can increase water loss rather than assisting with water replenishment. In other words these substances may contribute to dehydration rather than hydration. Alcohol and caffeinated drinks like coffee cause water loss by increasing urination. These substances are referred to as diuretics and should be kept to a minimum or avoided altogether when dehydration is present.
Maintain A Balanced Diet With Unprocessed Foods
Since food contributes approximately 20% of the daily water intake, a balanced diet should therefore be an important part of maintaining hydration levels. Foods also contribute electrolytes (salts) which may be lacking in water alone. Some foods can counteract rehydration.
Processed foods may laden with preservatives and food additives, including high salt quantities, which can have a dehydrating effect. The body tries to remove these excess salts and water is inadertently lost in the process. Therefore unprocessed foods, particularly fresh fruit and vegetables, tend to be better options for hydration.