DEAR DR. BLONZ: I am hoping you can provide a logical explanation of acidity and alkalinity in food and the body. My interest relates to information I’ve read that the body can maintain itself better with a more alkaline diet. Is this so? Also, can a pH test of saliva be an accurate determination of the body’s acid/alkaline level? -- S.F., Janesville, Wisconsin
DEAR S.F.: The degree of acidity or alkalinity is expressed in terms of pH, which is a mathematical calculation based on the hydrogen ions present. Each hydrogen ion has a single positive charge. Substances considered “acidic” have high concentrations of hydrogen ions, while those considered “basic” have a low concentration.
A pH of 7 is considered “neutral.” Distilled water has a pH of 7.0. The greater the distance from 7.0 in either direction, the stronger the acid or base. For example, coffee is considered weakly acid with its pH of 5.0, but battery acid, a strong acid, has a pH of 0.8.
As a general rule, the human body is slightly alkaline, with its pH kept within a very narrow range: between 7.35 and 7.45. (There are exceptions, such as there being an acid environment in the stomach to facilitate digestion.) There are overlapping systems designed to keep our pH within those limits, since essential chemical reactions in our bodies can be impacted if the pH gets out of whack.
The pH of foods varies widely; check bit.ly/2VnHpPO for a table of the pH values of common foods and ingredients compiled by Clemson University. A healthy body is quite adept at dealing with these pH variances, making adjustments while foods are in the digestive system, and then after they are absorbed, as needed. The kidneys play a key role: The pH of urine changes according to our state of health and any disease processes that might be underway, and also based on what we eat, drink or do. Aside from urine, our perspiration and breath also help to keep body pH in its optimal range.
You mention doing a pH test of saliva, but this is of questionable value as a general diagnostic, or as an indicator of your body’s pH. Aside from the fact that salivary pH varies normally, it can be affected by ongoing dental issues and by the flora that live in the mouth.
Certain disease states, anxieties, stress and medications can all exert short-term effects on the body’s pH, but the systems are designed to compensate and keep things on track. There is no proven benefit to “eating alkaline” as an end in itself. A healthful, whole-foods, plant-based -- but not necessarily plant-exclusive -- diet, along with an active lifestyle, remains the best strategy.
Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.