Water is an essential element for our existence as it performs a number of vital functions in the body. It is a key component of the fluid that forms the basis of saliva that helps us to swallow, of synovial fluids that cushion the joints and of the fluids that fill our eyeballs and lubricates our eyes. It provides the medium for by which most of the chemical reactions in the body occurs, it acts as a cushion for the nervous system (cerebrospinal fluid), allows us to get rid of waste products principally via the kidneys and urine production, and helps to regulate body temperature by the process of sweating. 1,2,3
The body tightly controls its water volume and, under normal conditions, the volume fluctuates by less than 1% per day. Dehydration can be defined as a 1% or greater loss of body mass due to fluid loss e.g. urine, eye lubrication, sweating, breathing etc. 1,2,3
Research experiments using fluid restriction to induce dehydration, has shown that loss of body mass of about 1% can be seen after 13 hours, about 2% after 24 hours and nearly 3% after 37 hours when no fluids and only relatively dry foods are consumed. It was noted, however, that the subjects undergoing fluid restriction had a strong desire to drink and would have been unlikely to become dehydrated to such an extent accidentally. These experiments do show how quickly body fluid loss can occur and the importance of continued rehydration by the consumption of water. 1,2,3
If water losses are not sufficiently replaced, dehydration will occur and extreme dehydration is very serious and can be fatal. More mild dehydration (about 2% loss of body weight) has been shown to result in headaches, fatigue, increased stress/anxiety, reduced physical performance and cognitive function. Some studies have refined the level of dehydration, where detectable symptoms and changes occurred, to the following: in males, dehydration of 1·59 % body weight loss and in females 1·39 % body weight loss. Such modest loss in body weight can occur in everyday activities, demonstrating the importance of maintaining optimal hydration. Taking into consideration various changes attributable to factors such as ambient temperature, physical activity, state of health, the European Food Safety Authority has recommended that the appropriate water intake should be approximately 2 litres per day for women and 3 litres per day for men. Higher water intake requirements will, of course, be higher for athletes and those that are physically active in hotter climates.4,5,6
The Stratum Corneum (SC) of the skin consists of the essential barrier between the internal and external environment. Although most of the skin is between 2-3mm (0.10 inch) thick, the SC plays a vital role in forming a protective barrier and helps to prevent percutaneous entry of harmful pathogens (e.g. germs) into the body. In addition to serving as a physical barrier, the SC has other important functions, including the regulation of body heat (thermoregulation), respiration and maintenance of the body’s water content – transepidermal water loss (TEWL) Stratum Corneum properties and its protective function can be modified by various internal and external/environmental factors.7
So what happens to human skin when the body becomes dehydrated?
Any change in the structure of the stratum corneum (SC) is potentially associated with alterations of both its barrier function and water holding capacity. Decreased hydration with reduced elasticity of the stratum corneum is responsible for cracks and fissures in the skin. The rate of TEWL is higher in dry skin than in normal skin where the integrity of the barrier function is not disturbed. The impaired barrier in skin conditions such as psoriasis and atopic eczema makes the SC less efficient in excluding substances that come in contact with the surface and patients with skin conditions e.g. atopic dermatitis are believed to be more prone to contact dermatitis than a normal population and those with psoriasis more susceptible to flare ups after exposure to chemicals.8
How can you tell if you are dehydrated?
One simple test is to gently pinch the skin on your hand …. hold for a few seconds and then release the skin. If the skin springs back you are not dehydrated, if the skin remains tented (turgor) then it is a sure sign that you are dehydrated and need to drink at least two glasses of water immediately. Another way of checking is the simple observation of the colour of your urine when you go to the toilet. Some charts have numerous colour options but the simple chart that the NSW Government Health Department has on their website “Beat the Heat” is probably the best and easiest to use:-
REMEMBER IF YOUR URINE IS DARKER THAN THAT INDICATED THEN YOU ARE SERIOUSLY DEHYDRATED AND SHOULD ATTEND YOUR NEAREST HOPSITAL EMERGENCY DEPARTMENT
URINE COLOUR CHART
This urine colour chart will give you an idea of whether you are drinking enough water or you are dehydrated (lost too much water from the body)
|Very Dehydrated ……. DRINK 1 litre of water|
|Dehydrated …….. DRINK 2 -3 glasses of water|
|Somewhat Dehydrated ……. Drink 1 glass of water|
|Hydrated, You are drinking enough, continue drinking as normal|
Also read our blog “HEALTHY SKIN and WATER INTAKE – PART 2“
Popkin B. M. et al.; Water, Hydration and Health; Nutr Rev. 2010 August ; 68(8): 439–458. doi:10.1111/j.1753-4887.2010.00304.x.
- Benelam B. and Wyness L.; Hydration and health: a review; Journal compilation © 2010 British Nutrition Foundation Nutrition Bulletin, 35, 3–25
- Je´quier E. and Constant ; Water as an essential nutrient: the physiological basis of hydration; European Journal of Clinical Nutrition (2010) 64, 115–123
- Ganio M. S. et al.; Mild dehydration impairs cognitive performance and mood of men; British Journal of Nutrition (2011), 106, 1535–1543 doi:10.1017/S0007114511002005
- Armstrong L. E. et al.; Mild Dehydration Affects Mood in Healthy Young Women; The Journal of Nutrition Ingestive Behavior and Neurosciences; First published online December 21, 2011; doi:10.3945/jn.111.142000
- EFSA (2008). Draft dietary reference values for water. Scientific Opinion of the Panel on Dietetic Products, Nutrition and Allergies, (agreed on 11 April 2008 for release for public consultation). (http://www.efsa. europa.eu/it/scdocs/doc/1459.pdf