Thank You Yoshi that link is very helpful. Believe it or not my interest in alkaline/acid content of food was sparked by visiting Amma who had a book on it, on display,at one of her visits to America.Separating the facts from the fads The widespread confusion is due primarily to the fact that there are four distinct acid/alkaline factors in human health and nutrition. Following is a careful discussion of each: a mini-course in biochemistry which you can refer to the next time someone says to you, "Oh, I never eat oranges; they're too acid." First of all, what is an acid? An acid is any substance which, in solution with water, will turn litmus paper red, taste sour, and chemically release hydrogen ions. Acids are referred to as strong or weak, depending on their concentration of hydrogen ions, and this factor is measured on a pH scale which uses pure water as a neutral point of 7.0 . Values less than 7.0 are acid, and the stronger the acid, the lower the pH. Common acids include acetic acid (vinegar), and hydrochloric acid, the digestive fluid secreted by the lining of your stomach. Alkaline (also called base) substances, in water solution will turn litmus paper blue, taste bitter, and chemically accept hydrogen ions. Alkali, or bases, are measured on the pH scale in numbers greater than 7.0, and the stronger the base, the higher the pH, up to 14. Common bases are sodium hydroxide (lye), and sodium bicarbonate (baking soda). NOTE: Acid and alkaline are value neutral terms. Neither is good nor bad, but both have definite properties and essential activities in the human organism. The four factors of acid/alkaline balance related to nutrition are:
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1. The acid/alkaline balance of the blood and body fluids.
2. The acid/alkaline quality of certain foods before they are eaten.
3. The acid and alkaline chemistry of digestion.
4. The effect of foods AFTER they are digested and metabolized, often referred to as acid/alkaline "residue" or "ash".
1. Acid/alkaline "balance"
In medical terminology, when one speaks of the acid/alkaline BALANCE, or the acid/alkaline equilibrium, it refers to the relative pH of the blood, which must be kept within a narrow range around 7.4 (slightly alkaline). This vital function is accomplished most efficiently by a number mechanisms, including automatic buffer systems in the blood, and the pH regulating action of the lungs and kidneys. In ACIDOSIS, or acidemia, the pH of the blood is too acid (less than 7.35). In this case, blood buffer systems will adjust towards alkaline, and the rate of breathing will increase to remove carbonic acid via the exhalation of carbon dioxide (CO2). Next, the kidneys increase the acidity of the urine, and balance is quickly restored. NOTE: Acidosis is NOT caused by eating acidic foods such as lemons and oranges. It is most often the result of impaired metabolism, such as in diabetes or starvation, kidney disease, or respiratory disorders that limit the release of CO2 from the lungs. ALKALOSIS or alkalemia, is less common than acidosis, but can result from hyperventilation (too rapid breathing), loss of stomach acid due to excessive vomiting, or over-use of antacids and/or ulcer medications. In this case, blood buffer systems adjust toward acid, and breathing becomes more shallow to conserve CO2 and raise carbonic acid levels in the blood. Once again, the kidneys contribute to the "balancing act" by excreting more alkaline urine.
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ACID FRUITS Fruits are sometimes classified as either acid, sub-acid, or sweet.
This differentiation has nothing to do with the acid/alkaline balance in the blood, which is not affected at all by the acid content of a food. In fact, as you will see, the metabolism of most all types of fruit results in an alkaline ash, with the exception of cranberries and some varieties of plums. Once again, acidosis is not caused by eating "acid" fruits. Whatever negative effects individuals may experience from eating citrus fruits, are most likely due to food allergy, fermentation in the gastrointestinal tract due to maldigestion, or localized irritation from the citric acid in the fruit; all of which are common. The only reason to classify fruits this way, other than the dubious practice of "food combining" may be to help in the botanical description of the food. For example, oranges, grapefruit, lemons, limes, tangerines and kumquats are citrus fruits containing citric acid. Apples, sometimes classified "sub-acid", contain malic acid. Cranberries contain benzoic acid, etc.
Stephen Cherniske, M.Sc.
