One of the diets that has been around for a long time is the acid/alkaline theory of disease. This diet is prevalent in alternate health circles and contends one must keep one's body at the proper pH by eating primarily “alkaline forming foods.” By doing this in some way your body will become “more alkaline” and healthy. Alternative practitioners may use systems that measure urine pH plus other factors to assess metabolism. Also, some measure saliva pH. Salivary pH is effected by bacteria in the mouth. Neither method determines the internal pH of the body, and I do not give much credence to this theory for a number of reasons.
What is pH and Why is it Important?
Inside the human body, the acid-alkaline balance is important because many functions in the body occur only at a specific pH. pH is the amount of free hydrogen that is measured on a scale of 1 to 14, and denotes the level of acidity or alkalinity. A pH value of 7 is neutral; below 7 acid and above 7 alkaline. Different parts of the body have different levels of acidity and alkalinity. For instance, the blood is alkaline, with a pH between 7.35 - 7.45. Urine pH can vary between 4.5 - 8.0, so it can be either acid or alkaline. Heart pH varies between 7.0 - 7.4 and is alkaline. Muscle pH is between 6.9 and 7.2 and saliva pH 6.0 - 7.4
All chemical reactions in your body are initiated by enzymes, and all enzymes function in a very narrow pH range. If your blood changes its acidity or alkalinity for any reason, your body physiology is programed to quickly change your pH back to normal. For example, when you hold your breath, carbon dioxide accumulates in your bloodstream and very rapidly turns your blood acidic. You will become uncomfortable or even pass out. This forces you to start breathing again, and the pH returns to normal.
Alkaline and Acid Foods
There is confusion between the terms acid or alkaline ash and acid and alkaline forming, as they are often used interchangeably. Alkaline ash foods are those that contain large quantities of magnesium, calcium, potassium and/or sodium. Acid ash foods are those that contain chloride, phosphorus, sulphur, or other minerals that form acid compounds. In investigating how different foods might affect the acid-alkaline balance, various foods were burned to ash in the laboratory and the pH of the resulting ash was measured. These foods were then classified as acid, alkaline, or neutral ash foods. As far back as 1919, one of the studies performed at the University of Minnesota Medical School, published in the Journal of Biological Chemistry, evaluated the effect of diet on the alkaline reserve of the blood and found that “the alkaline-reserve in man is not endangered by acid-forming diets.” For purposes of our discussion, I will refer to acid or alkaline forming foods. We have studies on the effects of food and urine pH. All animal products, beans, seeds and grains tend to have an acidifying effect, while fresh vegetables and fruits, with a few exceptions, have an alkalinizing effect (on the urine). Plums, cranberries, and prunes leave acid residues in the body because they contain benzoic acid which is not oxidized. Cranberries help prevent recurrent urinary tract infections, not because of their acidity, but because they contain chemicals that prevent bacteria from sticking to urinary tract cells.
The Acid-Base Balance in the Body
No matter whether a food leaves an acid or alkaline ash, when it enters your stomach it will become acidic. All foods that leave the stomach are acidic but when they enter the intestines, secretions from your pancreas neutralize the stomach acids, and the food in the intestines becomes alkaline. You cannot change the acidity of any part of your body except your urine by your diet. Because your urine is contained in your bladder it does not effect the pH of any other part of your body. You could eat large amounts of ascorbic acid, vinegar, or citrus fruits and you will not change the acidity of your stomach or bloodstream.
The acid-base balance in the body is tightly controlled by a number of factors, including your lungs, calcium and mineral reserves in your bones, your blood and your kidneys. For instance, when you take in more protein than your body needs, your body cannot store it, so the excess amino acids are converted into organic acids. These acids would acidify your blood if it were not for the calcium leaving your bones to neutralize the acid and control the blood pH. Over a long period of time, eating an acid forming diet may have an effect on your alkaline mineral reserves in the bones. Because of this many researchers believe taking in too much protein can cause osteoporosis. Remember your bone calcium and other minerals are in a dynamic state with the blood and are used as a buffering system. There are promoters of products such as “alkaline drinking water” or special calcium supplements, that are supposed to alkalinize your body or prevent cancer. In my opinion, there is no science behind these claims.
Summary
The beneficial effects of fresh fruits and vegetables in the diet have been recognized for a long time, and it is suggested that at least five servings a day are needed to maintain health. Meat and other animal
