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Two thirds of the human body is water. Water is an essential component involved in every function of the body. It helps transport nutrients and waste products in and out of cells. It is necessary for all digestive, absorption, circulatory and excretory functions, and for the maintenance of proper body temperature. You can live without food for several weeks, but you can survive only a few days without water.
Water must be continuously replaced since, on average, 250ml is lost on a daily basis just through breathing. Exact daily requirements vary depending on the climate and whether any type of activity is undertaken. But generally, drinking at least two litres of water a day is recommended to ensure your body has all it needs to maintain good health.
As we grow older, the continual loss of water becomes more evident. The human body is comprised of around 75 per cent water at birth, but this can reduce to 55 per cent by the end of a person’s life. This desiccation can be seen in the wrinkling of the skin.
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Water balance
Throughout history, theories about the way the human body acts have centered around the amount of water it contains. From blood-letting to lunacy to tidal flows, the most vital of liquids has been seen as the key to maladies and disease. With the average person being made up of two thirds water, is there any truth behind these ideas?
The ancient Greeks came up with a system of balance that they believed controlled our health - the four humours. The four elements - earth, air, water and fire - were said to need careful regulating in order to achieve a balance and give long life and good health. These ideas persisted all the way through the middle ages where common ailments were treated according to a supposed lack or excess of each of the related humours - blood, phlegm, black bile and yellow bile. Careful letting of any of these four elements was practised in order to restore balance. Surprisingly, some of these ideas have been revived by the medical community, especially the use of leeches to drain blood, as they also introduce a useful anti-coagulant into the body.
Another long-running belief was that the moon affected both the health of the body and the balance of the mind. This comes down to us in the word ‘lunacy’ and the myths of werewolves and madmen appearing at full moon. Studies have been conducted to investigate the correlation between acts of lunacy (and suicide attempts) and the phase of the moon, but little connection has been found.
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Biological tides
Taking this one step further, some argue that if the moon has such a dramatic effect on the Earth’s oceans, then it must have a similar relationship with our bodies, as water is such a large part of our make up. The theory argues that a mini tidal effect, especially in the liquid surrounding the brain, must have consequences on our well-being. However, the counter argument is that of scale. Whilst there is a marked and visible effect on the oceans and seas, which give us tides, the moon’s gravitational pull is interacting with a vast volume of water. The same rise and fall is not seen in a glass of water or even a container filled with the same amount of water as in the human body. The general scientific consensus therefore seems to be that the moon’s tidal effect on a human body is negligible or non-existent.
Although pull from the moon does not seem to affect us directly in this way, it does have a profound effect on the Earth and on numerous biological events - and these certainly do affect us.
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