How much water does our body need?

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#808080" TEXT="#080000" background="044b8573.jpg"> <div> <FONT SIZE="5" COLOR="#FFFFFF" FACE="Arial" ><B>MEDI-MAIL</B></FONT><B>    </B><B> |     </B><A HREF="index.htm" TARGET="_top" TITLE="MEDIMAIL"><B>home</B></A></div> <div> <A HREF="jobs26.htm" TARGET="_top" TITLE="Medical Information">Medical Information</A>   |   <A HREF="jobs27.htm" TARGET="_top" TITLE="Swine Flu H1N1">Swine Flu H1N1</A>   |   <A HREF="jobs28.htm" TARGET="_top" TITLE="Childrens health">Childrens health</A>   |   <A HREF="jobs29.htm" TARGET="_top" TITLE="Travel Health">Travel Health</A>   |   <A HREF="jobs2b.htm" TARGET="_top" TITLE="Malaria">Malaria</A>   |   <A HREF="jobs2c.htm" TARGET="_top" TITLE="Vitamins">Vitamins</A>   |   <A HREF="jobs3c.htm" TARGET="_top" TITLE="The Doctor will see you now">The Doctor will see you now</A>   |   <B>How much water does our body need?</B>   |   <A HREF="jobs39.htm" TARGET="_top" TITLE="Tips">Tips</A>   |   <A HREF="jobs49.htm" TARGET="_top" TITLE="Telltale signs of diabetes">Tell-tale signs of diabetes</A>   |   <A HREF="jobs4a.htm" TARGET="_top" TITLE="NaturalMedicines">NaturalMedicines</A>   |   <A HREF="jobs4e.htm" TARGET="_top" TITLE="Did You Know...">Did You Know...</A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#808080" TEXT="#080000" background="045d2083.jpg"> <div> <IMG SRC="0925e370.png" border=0 width="94" height="55" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </td> <td valign="top" height=390 width="100%" BGCOLOR="#FFFFFF" TEXT="#080000" background="04605053.jpg"> <div> <I>How much water does our body need?</I></div> <div> We lose an amazing 2.5 litres of liquid a day, so how do we keep ourselves hydrated?</div> <bR> <div> By the time you've</div> <div> read this article</div> <div> your body will</div> <div> have lost a quarter</div> <div> of a glass of water</div> <bR> <div> We are constantly battling against dehydration. The human body is made up of 70 per cent water, and in a typical day, without doing anything,</div> <div> we lose about 2.5 litres of this pre </div> <div> cious resource - essential for almost</div> <div> every bodily function, from regulat </div> <div> ing body temperature to removing</div> <div> waste products.</div> <div> It's easy to become dehydrated, whatever the weather, simply by not drinking enough. In fact, by the time you have finished reading this arti¬cle, your body will have lost 30m1 (quarter of a glass) of water not just from forming urine but also as vapour from the lungs and from the skin in sweat. For normal functions to be preserved, the body must attempt to keep itself as stable and regulated as possible, and it has developed complex mechanisms to ensure the mount of water present is as stable as it can be, despite variations in environment or water intake.</div> <bR> <div> THE GREAT BALANCING ACT</div> <bR> <div> Hydration levels are regulated by a part of the brain called the hypothal-amus. When the blood becomes too concentrated as a result of not enough water, it stimulates the sen-sation of thirst.</div> <div> The hypothalamus also causes a gland in the brain, the pituitary, to release anti-diuretic hormone (ADH), which acts on the kidneys to encour-age them to make less urine and reab-sorb water into the blood. This results in the blood becoming less concen-trated, and this in turn is detected by the hypothalamus, which reduces the secretion of ADH and maintains water balance.</div> <div> It's a clever mechanism to ensure</div> <div> that concentrations in the blood remain stable throughout the day. However, if water intake is reduced, the system has difficulty coping and dehydration can occur.</div> <bR> <div> THE SYMPTOMS OF DEHYDRATION</div> <bR> <div> Dehydration - the term used to describe when body water content drops below normal levels, resulting in potassium and sodium levels (collectively known as electrolytes) in the blood becoming too concen¬trated - produces clinical symptoms after about two per cent of the body's water has been lost.</div> <div> Initially, someone who is dehy-drated begins to experience a head¬ache which progresses to muscle cramps and dry mouth and skin. Their urine output also decreases as ADH is secreted in response to the reduced water levels. At around five per cent loss, fatigue, even faint¬ing, can be experienced. This stage is reached in otherwise healthy indi-viduals only if they neglect to eat or drink for 12 to 15 hours or more. The kidneys begin to shut down as an emergency measure to preserve water - known as acute renal failure. If this level of dehydration lasts more than a few days, there can be long-term damage to the kidneys, formation of kidney stones, damage to muscles and joints and raised cholesterol and blood pressure. Left untreated, ten per cent dehy¬dration results in delirium, loss of consciousness and urine ceasing to be produced entirely. After about 15 per cent is lost, death occurs. Exactly how long it takes to become dehydrated, and how quickly it takes to progress from mild to moderate to severe dehydration, depends on many things, including how hydrated the person was before, their kidney function, age and the reason for the loss.</div> <bR> <div> THE CAUSES OF WATER LOSS</div> <bR> <div> In addition to not drinking enough, dehydration can also be caused by illnesses such as gastroenteritis, as large amounts of fluid can be lost due to diarrhoea, vomiting, and fever causing excessive sweating. We sweat more during physical work, which means water intake must be increased to compensate for the loss. In the summer, we lose fluid slightly faster due to increased perspiration. Those who have experienced exten¬sive burns are also at risk of dehy¬dration as fluid is lost through the damaged skin.</div> <div> Alcohol acts as a 'diuretic'. This means it stimulates the kidneys to increase</div> <div> the amount of fluid lost by the body, and therefore can contribute to dehy-dration. In fact, the sensations of</div> <div> a hangover are related in part to dehydration. Tea and coffee are also diuretics, but their action on the kidneys is mild and rarely leads to dehydration.</div> <bR> <div> TAKE A LONG DRINK OF WATER</div> <bR> <div> We need to drink enough fluid for the kidneys to produce a minimum of 30m1 of urine an hour - in order for them to filter toxins from the blood. But thirst is not always a good indi-cator to assess dehydration.</div> <div> In those aged over 50, the thirst sen-sation decreases, and continues to diminish with age, along with the ability to regulate body temperature. For this reason older people are par¬ticularly susceptible to dehydration.</div> <div> The best way of ensuring you are properly hydrated is by looking at the colour of your urine. If it is consis-tently dark, you should increase your fluid intake. If it looks like water, then you're drinking too much and should cut back. The ideal to aim for is a pale straw colour, and to empty your full bladder about four times a day.</div> <div> Dehydration can be diagnosed through a blood test that looks at the concentration of electrolytes and other chemicals in the blood.</div> <div> Rehydration fluid is made up of a powder mixed with water that replaces minerals, salts and sugars as well as water. It can be prescribed by a doctor or bought over the counter.</div> <div> In extreme cases, people who are dehydrated need to be admitted to hospital and rehydrated using an intravenous drip containing a mix-ture of water, sugars and salts.</div> <div> Babies and the elderly are at par¬ticular risk because their bodies are less able to maintain water levels.</div> <bR> <div> TOO MUCH OF A GOOD THING</div> <bR> <div> The Food Standards Agency advises drinking between one to two litres of water every day. When exercising to the extent that you sweat, water intake should be increased by one litre per hour of exercise. It's impor¬tant to remember that if you eat your five-a-day of fruit and vegetables, this can provide one litre of water. Water intoxication - when so much water is consumed that the body is unable to excrete it fast enough, with the result that the blood becomes too diluted - can ultimately lead to coma, but this is extremely rare.</div> <div> Those with long-standing kidney damage often have their fluids restricted so they do not consume too much liquid. This is because</div> <div> damaged kidneys struggle to process the water in the blood out of the blood ves-sels and into the extremities, or even the lungs - a condition known as oedema. But with healthy kidneys this is not a concern.</div> <bR> <bR> <bR> <bR> </td> </tr></table></body>