DEAR DR. BLONZ: My husband and I have just made the move to quit smoking. We are now trying to flush our systems of any toxic materials, so we are drinking a lot of water and have been eating very lightly. Is a weeklong liquid diet a good idea to help take the load off the body so that it can concentrate on healing? We are also trying to rest a great deal. Any other suggestions on how to get through this in the best way? -- T.S., Charlotte, N.C.

DEAR T.S.: Your body will soon gain the upper hand. Water is a great conduit for elimination, so you are on target there, but so is healthful food. Many people have an urge to eat more after they quit, so you should have some foods around of low caloric density. Eat normally at mealtime, but be alert to the quality of your snacking. Good between-meal foods would include fresh fruits, cut vegetables, pretzels (whole wheat if palatable), and even sugar-free gums and candy. Other suggestions might include rice cakes, air-popped popcorn, whole-grain dry cereals, raisins and other dried fruits, and even some nuts and seeds. Small meals, eaten slowly, can help fill you up without contributing an excess of calories.

You note that you are resting, but if you have the OK from your doctor, it may help to begin going on walks, riding bikes, dancing or any other activity the two of you might enjoy. Not only will this help control any potential weight gain, it will be an important first step in telling your lungs and muscles to get in step with your new plane of existence. It also can provide some of the same pleasant substances, known as endorphins, that the body produced in response to smoking. They often play a role in the cravings that make it difficult to stop smoking, but studies have shown that you can get a similar kick from exercise. How's that for a great turn toward health! Please do check with your physician first, in case there are other issues that need to be considered.

Don't give up if you gain a few pounds. Those can be lost later. The key is to get over the proverbial "hump" of four weeks or so, after which the worst of the withdrawal symptoms will be history. There are many programs and support groups around that can be of help. Finally, you definitely need to spend some time giving yourselves a pat on the back. I congratulate you both.

DEAR DR. BLONZ, I learned in school that riboflavin in milk is destroyed by light. If that is true, why is milk often sold in clear containers? Am I wasting my money by paying more for it in opaque containers? -- N.F., Puma, Ariz.

DEAR N.F.: Milk is a perishable food, and exposure to natural light or bright flourescent light can destroy a percentage of the riboflavin (vitamin B2), vitamin C and vitamin B6, and also encourage the development of "off" flavors. Light intensity and the duration of exposure determines how much of these nutrients will be destroyed.

Appropriate temperature control is an important factor in nutrient preservation, but proper containers can also offer protection. Storage in an opaque container, such as a paper carton, seems to be best in this regard, with clear glass at the other end of the spectrum.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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: On National Public Radio, a University of Minnesota nutritionist claimed that whole-wheat flour today is so highly processed that it is absorbed by the digestive system just as quickly as white flour, and impacts blood sugar levels in the same way. The nutritionist recommended whole-wheat bread made from stone-ground wheat berries instead. How valid is the claim about processing? Does whole-wheat bread still have other nutrients that white bread lacks? Would whole-wheat bread made from sprouted wheat be a good alternative? -- D.W.M., via email

DEAR D.W.M.: Your mention of a University of Minnesota nutritionist speaking about whole grains suggests Dr. Joanne Slavin. She is definitely an expert in the field of whole grains, but I couldn't imagine her making such statements, so I had to check it out. I found the NPR program transcript online at tinyurl.com/cj6vstq. It seems you are misattributing statements by the other guest, Dr. David Ludwig, an esteemed pediatrician who studies obesity.

While there are different types of wheat being grown nowadays, in general, the whole-wheat flour of today is not much different than the whole-wheat flour of earlier times. The healthfulness of whole grains has led to a greater presence of whole-wheat flour in some processed foods, but that should not serve to denigrate the value of this important class of nutrient substances. A whole-grain bread will have nutrients, fiber and phytochemicals not found in white bread. This being said, however, some vitamins and minerals are often added to enriched white bread. I recommend that at least half our grains should be whole grains.

It is never a good idea to eat a bunch of carbohydrates on an empty stomach, whether it is sugar-sweetened soda, white bread, or even whole-wheat bread. It's best to eat in such a way that the glucose in carbohydrates has the smallest impact on blood sugar levels; eating sweets and carbohydrates on an empty stomach does the opposite. (About the only exception might be a piece of fruit, because fructose, or fruit sugar, is absorbed more slowly.) Having carbohydrates as part of a mixed meal that includes protein and fat will slow the release of the food from the stomach and accomplish the goal of minimizing the impact on blood sugar. All the better if you eat slowly.

I encourage you to re-read that NPR piece on whole grains. I support what Slavin said; it is definitely a more positive and practical approach. You also asked about sprouted whole wheat. This does represent an alternative, but choose it only if you enjoy the flavor and texture, not because it is significantly superior. Always check the Nutrition Facts labels on products you buy, as well as the list of ingredients. Having a whole grain in the first position is a definite asset, and if the package displays a whole grain stamp (wholegrainscouncil.org), as mentioned on the radio show, all the better. All of this provides good guidance.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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: Please tell me what you know about activated charcoal as a dietary supplement. How much should one take, and how well does it work as a blood purifier? -- G.L., San Jose, Calif.

DEAR G.L.: Activated charcoal is a specially treated and purified form of charcoal. It is a very fine powder, giving it a very large surface area. Fine, powdered charcoal is an "adsorbent," which means it has an ability to attract and hold on to substances on its surface. (Contrast this with "absorbent," where liquids are soaked up as with a sponge.)

This adsorbency makes activated charcoal useful for water filters because it can grab and hold heavy metals, unwanted minerals and odor-causing particles. It is often the key ingredient in water pitcher filters designed to be changed every couple of months. In addition, activated charcoal may be recommended after an accidental ingestion of poison -- the adsorbent qualities hold on to the poison and prevent it from being absorbed through the intestines and reaching the bloodstream. According to a statement from the American Academy of Clinical Toxicology, activated charcoal is more likely to be beneficial if administered within one hour of poison ingestion.

It is unclear how activated charcoal could work as a blood purifier; it would be tough for it to purify the blood if it never gets absorbed into the body. Also, it's not be wise to consume activated charcoal on a regular basis, as it will also reduce the absorption of nutrients present in the stomach at the same time.

DEAR DR. BLONZ: I am concerned about the use of gums as food additives. Specifically, I am concerned about xanthan gum as used in salad dressings and chocolate syrup. Could regular daily use of chocolate syrup and salad dressing, over seven years, cause xanthan gum toxicity, or perhaps a gum buildup in the lungs or liver? -- J.T., Monroe, La.

DEAR J.T.: Vegetable gums such as agar, locust bean gum, tragacanth, xanthan gum and pectin are used as food additives to improve texture and spreadability, and to provide the slippery "mouth feel" normally associated with a butterlike product. These compounds are built like a carbohydrate, but they're not digestible so they don't contribute any calories to the item.

Xanthan gum is usually made from a specially fermented corn syrup. It was created at a USDA research station in Peoria, Ill., as part of a project to find new uses for surplus corn. Xanthan gum helps to thicken the texture of a food and it has proven itself to be quite versatile. Aside from syrups and salad dressings, it is found in pudding, sauces, baked goods and desserts. Because it is made from corn, xanthan gum should be avoided by individuals allergic to corn, but aside from that there do not appear to be any problems associated with its use. That means that when consumed as an additive in other foods, there is no evidence that it can build up or cause toxicity.

DEAR DR. BLONZ: Asian restaurants often list bean curd in their dishes. Is bean curd the same as tofu? Are they both made from soy products? I have searched forever for this information, and hope you can help. -- J.C., Chicago

DEAR J.C.: Bean curd is synonymous with tofu, both being soy products made with soybeans that have been soaked, crushed, cooked and filtered. Calcium sulfate is then added, causing the soy pulp to form a gel. The water is then removed as the soy is pressed into cakes.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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.