Understanding which foods promote alkalinity and which cause acidity in the body can have significant health implications. In general, body tissues thrive in alkaline environments, the blood being a great example. Many disease processes, including the growth and replication of pathogenic microorganisms, thrive in acidic environments. The average diets in many industrialized nations have become much more acidic over the last century, which may be related to the increased rates of some diseases.
Alkalinity and Acidity Defined
A substance that sheds hydrogen ions while in solution is considered an acid. The more hydrogen ions a solution has, the stronger its acidity and the greater its ability to dissolve other materials. The pH scale is used to determine relative acidity and is calibrated from zero to 14. Higher pH values connote lesser amounts of hydrogen ions, which are considered alkaline or basic. Neutral is represented on the scale by the number 7, which is what purified water is at room temperature. Many cells and tissues in the body require an alkaline medium to be efficient in their duties, such as blood, which functions best at a pH between 7.3 and 7.4. Other tissues and organs, such as the stomach, require acidic environments, which is why gastric juices are often between 3 and 5 on the pH scale. The biochemistry of food greatly affects pH levels within the body and can help or hinder its processes.
Alkaline Promoting foods
It's important to understand that foods containing acids, such as citric acid, can have a strong alkalizing affect on the body. This may seem contradictory, but that is the way the biochemistry works in the body. As such, many alkaline-promoting foods are actually sour or bitter to the taste. According to Cornell University professor of nutrition, Martha H. Stipanuk, Ph.D., author of "Biochemical, Physiological and Molecular Aspects of Human Nutrition," fresh citrus fruits, especially lemons, limes and grapefruits, have the strongest alkalizing affect on body fluids and tissues. Consuming the juice or flesh of these fruits may cause a "sour" stomach or heartburn in some people, but its overall impact on the body is an alkaline one. Other strongly alkalizing fruits and vegetables that are less sour include watermelon, honeydew melon, cantaloupe, papaya, seedless grapes, strawberries, celery, parsley, kelp and wheatgrass. About the only fruits that do not promote alkalinity are ripe blueberries and bananas.
Acidity Promoting Foods
Although all fruits and vegetables are considered carbohydrates and contain sugars, such as fructose, they are in ratios and forms that are more beneficial to the body, especially if eaten in moderation. However, typical modern diets are rich in refined sugars, such as high fructose corn syrup, and include many preservatives and other artificial ingredients that have a negative impact on the pancreas and other tissues due to their high acidity and impact on hormones, as cited in the book "Contemporary Nutrition" by nutritionists Gordon M. Wardlaw, Ph.D., and Anne M. Smith, Ph.D., R.D. The standard American diet is also high in animal protein, saturated fats, hydrogenated oils, white flour and refined carbohydrates, such as pasta and white rice, which all promote acidity in the body. Although not considered food, artificial sweeteners, coffee, black tea, beer, liquor, wine and most pharmaceuticals are highly acidic and are consumed daily by the vast majority of Americans.
Health Implications
Consuming considerable amounts of acidic foods and beverages over many weeks or months can put the body into an "acidity crisis" because the blood and other tissues must remain alkaline. One method of maintaining alkalinity is to liberate minerals from bones and deposit them into fluids and tissues, which is a primary underlining process causing osteoporosis and arthritis, according to Gerald Litwack, Ph.D., author of "Human Biochemistry and Disease." Acidity also allows many pathogens to proliferate, which taxes the immune system, and may be a factor in mutagenesis and cancer.
References
- "Textbook of Medical Physiology -- Tenth Edition"; Arthur C. Guyton, et al.; 2000
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- "Contemporary Nutrition: Functional Approach"; Gordon M. Wardlaw and Anne M. Smith; 2009
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
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