Dehydration

Dehydration Effects on Health

Fluid intake occurs principally during drinking (about 60 percent) and eating (about 30 percent); 10 percent of fluid intake results from metabolic processes within the body.

Fluid loss occurs through excretion from the kidneys (which in resting conditions amounts to approximately 60 percent of the total fluid loss), excretion from the large intestine (approximately 5 percent), and evaporation of water from the respiratory tract and sweat secretion (about 35 percent). Excessive fluid loss can be fatal, because water is essential for human life: it constitutes nearly 60 percent of body weight and about 72 percent of lean body mass and forms the basis for all body fluids, among them blood. As water is the principal constituent of the body, even a 9 to 12 percent fluid loss can have serious consequences.

The body fluids have vital functions: they contribute to the transportation and absorption of nutrients, allow muscle contraction, and help in eliminating waste. For this reason, it is essential to maintain the correct parameters of these fluids, especially blood parameters, such as blood volume and blood pressure. In effect, the body tries to defend blood volume as much as possible also in hypohydration situations: when there are deficits in body water content, water passes from inside the cells to the bloodstream. Through this fluid exchange, dehydration causes a redistribution of body water, which largely derives from a depletion of the water content of muscles and skin. Thus, depletion of body levels of fluid can significantly stress the body, impairing physical performance.

Hence, dehydration should be limited, or better still, prevented by drinking more fluids. Yet if fluid intake cannot balance fluid loss, dehydration becomes more severe. The body tissues start to dry out to such an extent that cells may shrivel and malfunction.

Symptoms of dehydration can be thirst; dry mouth, skin, and mucous membranes; decreased sweating and urine output; headache; muscle weakness; excessive fatigue and tiredness; dizziness; cramps; fever; low blood pressure; and in the most severe cases, damage to internal organs, confusion, delirium, or even unconsciousness. Fluid loss rates can vary greatly depending on many factors. Some of them concern specific characteristics of each individual (e.g., gender, age, health status); others may result from climatic conditions, such as humidity and temperature.

Therefore, dehydration should be prevented by consuming drinks and foods high in water content, such as fruit and vegetables.

Global Warming

Research has shown that the average temperature of the Earth's near-surface air and oceans has been increasing since the 1950s. Many scholars claim that this general rise is due to the presence of specific gases in the atmosphere. These gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFCs), cause the so-called greenhouse effect—absorbing infrared radiation from the sun and trapping it in the troposphere, the lowest layer of the atmosphere, directly above the Earth's surface.

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