On Nutrition

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.

DEAR DR. BLONZ: There is a chelation dietary supplement product that I am interested in to help lower my risk of heart disease. I now take a statin for this same purpose. Is oral chelation effective? And if so, how long do you have to take the supplements? -- S.F., Las Vegas

DEAR S.F.: Chelation is indeed a therapeutic technique that has been investigated for heart disease, but that research involves an intravenous (IV) infusion -- not a dietary supplement. (More on that later.)

The concept of chelation relates to the ability of a substance to bind, or chelate (KEY-layt), other compounds and stop them from reacting or causing harm. One main substance used is EDTA, short for ethylenediaminetetra-acetic acid. This is the same substance in the lavender-topped test tubes used when you go in for a complete blood count: The EDTA in those tubes chelates the iron in your blood and prevents it from clotting.

EDTA is very poorly absorbed when taken by mouth. After you swallow it, the EDTA has no choice but to travel the entire length of the digestive tract, its binding ability intact. There have been medical uses of oral EDTA to bind toxic intakes of unwanted heavy metals, such as mercury, arsenic, lead, cadmium or iron, that were inadvertently consumed. In such cases, it must be noted that the EDTA can also bind essential minerals, such as calcium and manganese, and escort them out of the body before they might be absorbed. There is no way to “direct” the EDTA to grab only toxins or certain unwanted substances. Therefore, oral EDTA should be limited to specific uses under medical direction.

The administration of EDTA directly into the bloodstream via an IV bypasses the poor-absorption issue. Intravenous chelation therapy has legitimate uses in systemic heavy metal poisoning, metabolic conditions where minerals accumulate, or diseases where access to certain minerals is key to the progress of the disease.

Your question, however, relates to oral chelation for heart disease. I was unable to find any competent and reliable evidence to support the safety and efficacy of oral chelation therapy for heart disease. As I mentioned above, there was a study looking at this issue: The National Institutes of Health helped fund a major clinical trial using an IV infusion of EDTA to determine if it might have some application to heart disease.

Referred to as TACT (Trial to Assess Chelation Therapy), the study did report a beneficial effect, but only for patients with diabetes. I want to point out, again, that this is EDTA given in an IV, not taken orally. You can read more about this use of chelation at nccih.nih.gov/health/chelation.

At the bottom of that page is a link regarding the FDA’s issuance of warnings to marketers of over-the-counter oral chelation products, and the dangers and false claims associated with such products.

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.

DEAR DR. BLONZ: I have a follow-up suggestion to the recent column on storing bread in the freezer. Like the previous letter-writer, I live alone, and I like to cook and freeze leftovers in single-serving portions. With my bread, I usually double-wrap the loaf: I put the original package in one of the larger plastic sleeves that come with the daily paper, then twist-tie it shut after making sure all the air is out of the bags.

Now for my question: Does freezing milk affect its quality or safety? I balk at paying almost as much for a quart of milk as I do for a gallon. I have a lot of freezer space, and have been freezing milk in quart mason jars. I’m especially careful to leave at least two inches of space at the top, between the milk and the lid, to allow room for expansion of the liquid as it freezes. If you violate this principle, I’ve learned, the glass jar is likely to crack. Is milk safe to drink after having been frozen and then thawed slowly in the refrigerator? -- J.W., Tucson, Arizona

DEAR J.W.: Your bread-freezing technique sounds great. It is always gratifying to find second-generation uses for the serviceable plastic bags that come into our possession.

Freezing is a safe and acceptable way to store milk. Changes in nutritional value are negligible, but there may be a few minor changes in the way the milk appears and tastes. The freezing process can cause a breakdown in the homogenization, which is the process that distributes the milk fat evenly throughout the milk. Of course, this will not be an issue with nonfat milk; with other types, however, an occasional drop of fat may be seen floating around. Give the milk a good shake before drinking.

The taste and appearance changes depend on the speed at which the milk is frozen. A slight change in taste, and/or some loss of color, is possible. These are very minor changes, and the milk remains a wholesome food. A good rule of thumb is: the faster the freeze, the smaller the damage.

I recommend that you put your well-sealed containers next to the freezer wall or on a metal shelf, where they’ll freeze quickly and remain solid for the duration of their storage. Remember, also, that because milk is a rich source of nutrients, it provides an ideal food for bacteria and other microorganisms. Pasteurization helps destroy most, but not all, of the bacteria present at bottling. Freezing doesn’t destroy microorganisms, it just suspends or slows their growth. Keep in mind that the quality of a defrosted milk, or of any other frozen food, will be no better than it was at the time it was frozen.

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.