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Coffee and the kidneys.

Caffeine has long been recognized as one of the most gentle agents that stimulate the kidneys with the least harmful side effects. Ironically, the moment any kidney trouble develops in an individual, the first thing banned from his diet is usually coffee, tea, and other caffeine-containing beverages. In many cases of renal difficulty, liberal intake of these beverages may be of greater benefit to the kidneys than avoiding them.

The kidneys are two bean shaped organs located in the mid-back region of the body. They extract the end products of metabolism, potentially harmful, or toxic substances converting them to urine. It thus maintains the balance of acidity and alkalinity in our blood, as well as the healthy ratio between our minerals salts and other normal soluble components.

In average adults, each kidney is about four inches long, two inches wide, and one inch thick. They weigh about four to six ounces. In this small volume, they contain over a million nephrons. Blood is pumped through millions of capillary tubes which lead into the nephrons. Dissolved salts and foreign matter pass through the walls of the capillary within the central walls of the nephrons. About 98% of the blood is returned to the main stream, but 2% containing excess salt or foreign matter is eliminated as urine.

About a quart and a half of urine is excreted daily by the average adult. The efficiency of a normal kidney is a remarkable aspect of the human body. Every day during the circulation of the blood, the kidneys will draw off approximately 180 quarts of fluid from the blood. It will filter and otherwise purify it and then return about 175 quarts to the bloodstream, while the remainder is eliminated.

The kidneys help control the body's acidity by absorbing filtered bicarbonate ions in exchange for chloride ions by secreting hydrogen ions. When too much alkali is present, the kidney compensates by absorbing fewer bicarbonate ions and more acid ions.

The kidneys also maintain normal salt concentration in the blood stream. If there is excess salt present, it is filtered out and expelled in the urine. If there is insufficient salt in the blood, less is taken out until normal conditions are restored.

The kidneys also regulate the volume of the blood. If it gets too large, they absorb more for elimination. It does this by absorbing sodium ions and by osmosis.

A diuretic is a medicinal product that increases the flow of urine in an individual. Naturally occurring caffeine in coffee is a diuretic and sometimes is effective when stronger diuretics do not respond. Coffee also can rectify excess sodium in the urine.

Caffeine increases filtration rate

Caffeine performs its kidney function by increasing their filtration rate. Other diuretics act by increasing the renal solute excretion or by inhibiting the transport of sodium.

Anything that increases the flow of urine without harmful side effects, it seems to me, should be welcome during a kidney difficulty. Practically all other diuretics have side effects such as nausea, vomiting, headache, etc.

From all the reasons at hand, I see no reason why coffee should be banned during the day. People should not drink coffee late at night unless they need it to keep awake, or unless they can sleep with it.
COPYRIGHT 1993 Lockwood Trade Journal Co., Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Coffee break with Dr. Samuel Lee
Publication:Tea & Coffee Trade Journal
Article Type:Column
Date:Feb 1, 1993
Previous Article:American altruism in action.
Next Article:Comments for 1993: Is the thrill gone?

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