On Nutrition by Ed Blonz

Carbonation and pH Levels

DEAR DR. BLONZ: Do carbonated beverages, such as soda water, interfere with the absorption of calcium or other vitamins and minerals? -- S.F., Berkeley, California

DEAR S.F.: Carbonated beverages are made by dissolving carbon dioxide gas in water under pressure. While these liquids tend to be slightly acidic, the body is designed to maintain the balance between acid and base (alkaline).

The key measure is pH: In chemistry, a pH of 7.0 is considered neutral; this is the pH of distilled water. The human body is slightly alkaline, and in good health, it will remain in a very narrow range -- between 7.35 and 7.45. Variations outside of this range can affect the chemical reactions essential for life. The master controller is our kidneys, the organs charged with removing/adjusting levels of substances in the blood while helping maintain ideal pH conditions within the body. The pH of our urine changes reflecting not only our state of health but also what we have recently consumed. Note that the body needs to be adequately hydrated for the kidneys to do their job.

Most foods measure on the acid side of the scale. Corn, for example, has a pH of 6.3; a carrot, 5.0; a typical salad-dressing vinegar, 3; cola soft drinks, about 2.4; and lemon juice, 2.3. The hydrochloric acid in our stomachs, used to break down foods, is a very strong acid with a pH of 1.0. On the alkaline (basic) side, baking soda and egg whites each have a pH of 8.0.

Regardless of its pH, soda’s (or any food’s) actual effect on the inner workings of the body depends on what gets done with the food’s chemical components. All things being equal, if you are adequately hydrated and eat anything that resembles a balanced diet, there is no need to be concerned about the effect that carbonated water might be having on the absorption of vitamins and minerals.

DEAR DR. BLONZ: The cereal my kids like says that it is made with whole grains, but when I checked the Nutrition Facts label, it says the dietary fiber is only 1 gram! What does “whole grain” on the label mean, nutritionally? -- S.P., Hayward, California

DEAR S.P.: A cereal product can be made with the whole grain or with parts of the grain. For food to state “made with whole grain,” the FDA requires that there be at least 8 grams of whole grain per labeled serving. If the product states “100 percent whole grain,” there cannot be any refined flour in the product.

Fiber tends to be in the fibrous outer coat (bran) portion of the grain, rather than the inside (flour) portion. Some grains have more fiber per unit weight than others. Also, some cereals use more of the non-fiber portion of the grain. Puffed cereals, for example, tend to use more of the flour portion than bran-based cereals.

The key comes from checking the entire ingredient list as well as the Nutrition Facts. I usually have cereal or granola with fresh fruit for breakfast and always look at this information before I buy. A good resource for information on whole grains and the various types of label terminology is the Whole Grains Council (wholegrainscouncil.org), an organization formed by the Oldways Preservation and Trust, a nonprofit food think tank.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.