DEAR DR. BLONZ: We've begun offering nonfat frozen yogurt bars as a snack for our child. The package says there are only 90 calories and, of course, no fat. The package also says "no preservatives," but the ingredient list includes a number of gels and gums, along with polysorbate 80 and carrageenan. If these aren't preservatives, what are they? Are they OK for our 7-year-old? -- FF.,. San Jose, California

DEAR F.F.: None of the ingredients you listed are preservatives. The gels and gums are thickeners, and the polysorbate 80 and carrageenan are emulsifiers designed to keep the yogurt mixture from separating while it freezes. All these components keep the nonfat flavored yogurt from turning rock-solid at freezer temperatures.

These treats usually provide about 100 milligrams of calcium and a small amount of protein. They won't provide the healthful phytonutrients found in a good piece of fruit, but they do represent a good alternative to chips, baked goods or candies. Even so, why not have a snack that's a win-win by making your own bars with fresh fruit and yogurt? You can find an assortment of recipes online, so look for one that appeals to you and your child.

DEAR DR. BLONZ: Is it reasonable to use antacids as a calcium supplement? -- P.R., Sun City, Arizona

DEAR P.R.: Calcium-based antacids tend to contain calcium carbonate, along with flavorings, colorings and a sweetener. And only about 40 percent of the weight of the calcium carbonate is actually calcium. That means that a 500-milligram calcium carbonate antacid will only provide 200 milligrams of calcium, which equates to 20 percent of the daily value for this mineral.

If you're considering such an antacid as a supplement, don't overdo it, especially around mealtime. The first stage of digestion requires an acid environment to begin the separation of foods into their individual nutrients. The excessive use of antacids can make your upper digestive tract alkaline, and that can mess with normal digestion.

As for bone health -- presumably what you're hoping to boost -- remember that it takes more than calcium to make bones. Although a bone is about 90 percent calcium by weight, other minerals such as magnesium, phosphorous, boron and silicon are needed. Vitamin D is also integral to the health of our bones, so you should be sure to have that nutrient in the mix.

For these reasons, food should be your first choice as a source of calcium. Aside from dairy products, calcium can be found in dark green vegetables, such as broccoli, kale, collards and arugula; legumes, such as soybeans and garbanzo beans; almonds; and fruits such as figs and apricots. Finally, aside from the calcium and other bone-building nutrients in your diet, it takes an active lifestyle and weight-bearing exercise to encourage the body to keep its bones strong.

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: I grew up with warnings about saturated fat, but in recent years, there have been positive health reports about chocolate -- which contains saturated fat. Am I missing something, or has there been a change in thinking? Does this open the door for chocolate? -- C.L., Los Angeles

DEAR C.L.: There's little doubt that chocolate would appear near the top of any list of people's favorite foods. Its taste, which has been cherished by many cultures throughout history, has a definite ability to please the palate. Americans lead the world in the consumption of chocolate.

A little background: Chocolate comes from the seedpods of the cacao, a tropical evergreen tree. The pods are harvested, and the inner white beans, called cocoa beans, are removed. These beans get roasted and ground into a thick paste called chocolate liquor, which is about 50 percent fat by weight. The fat in the liquor is referred to as cocoa butter.

Stearic acid, a saturated fat, is the main fat in cocoa butter (34 percent). The other main fats are oleic acid, which is the monounsaturate found in olive oils (30 percent), and palmitic acid (20 percent), which is another saturated fat.

Chocolate liquor serves as the base ingredient in the manufacture of all forms of chocolate. Solid chocolates are made by combining the liquor with additional cocoa butter and varying amounts of sugar. Milk is added if the product is to be a milk chocolate. Cocoa powder is made by extracting most of the cocoa butter from the chocolate liquor paste.

Getting back to your question: A systematic review in the January 2006 issue of Nutrition and Metabolism reported that stearic acid has a neutral effect on the risk of cardiovascular disease, and also that the phytochemical substances in cocoa beans have been reported to be protective.

So the door is definitely open, as you say. But what about other substances in chocolate?

There is caffeine in it, but not a significant amount. A 1.5-ounce bar of milk chocolate, for example, contains only about 9 milligrams of caffeine: the amount you would find in 1 tablespoon of coffee or less than 3 ounces of cola. A cup of hot cocoa has even less caffeine than that: about 5 milligrams. These amounts are too small to cause stimulation in most people.

Chocolate has traditionally been one of the first foods removed from the diet of acne-prone individuals, but controlled studies have shown that chocolate does not contribute to the outbreak of acne. And while it's possible for one to be allergic to any food, allergies to chocolate are rare.

Although chocolate contains sugar, studies have consistently shown that milk chocolate does not contribute to tooth decay. It's believed that the protein and minerals in chocolate help protect tooth enamel, and that the fat content prevents the confection from sticking to teeth. In addition, while a 1.5-ounce bar of milk chocolate contains 235 calories, it also supplies close to 10 percent of the daily value for riboflavin, phosphorous, calcium, manganese, zinc and copper.

All this should not be taken as a license to overindulge. After all, chocolate is high in fat. Whether it's milk chocolate or a higher-quality bittersweet, the fat content ranges between 50 and 75 percent of its calories.

The main idea here is that chocolate is not a staple food; it's a treat.

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: I read that orange-, pink- or red-fleshed fruits and vegetables contain beta carotene, but I wonder just what it is and how it got its name. I also recall you mentioning another antioxidant category with which I am completely unfamiliar: the "flavonoids." What are they, where did they get their name, and what foods contain them? -- S.H., Poway, California

DEAR S.H.: The naming of chemical compounds is a recipe of science and folklore. The root, or family name, of compounds is often taken from the name of the plant in which it was first discovered. From that point on, naming variations tend to be based on how the structure differs from the parent compound.

In the case of beta carotene, the parent compounds are the carotenes -- a group of yellow-red pigments widely distributed in plants, but most notably present in carrots (hence the name). The "beta" is the Greek letter designation for the fact that a key structure is in the second, or beta, position. (Alpha and gamma carotene have their identifying structures in the first and third positions, respectively.)

What's unique about these colorful compounds is that oxygen tends to combine with them in preference to other compounds and bodily tissues. The fact that beta carotene is a more attractive target means that its presence can "spare" other bodily substances and tissues from being oxidized, and possibly damaged in the process. That is the essence of what it takes to be called an antioxidant.

Please understand that oxidation is not a bad thing: It is entirely essential for life, and is used to release the energy from the foods we eat. After all, we breathe to get oxygen into our body. But when oxidation takes place at the wrong place and at the wrong time, it can lead to tissue damage that causes aging and can increase our risk of heart disease, cancer, certain forms of arthritis and a host of other ailments. A diet that is rich in whole-food antioxidants can help stave off unwanted damage due to errant oxidation. Nutrients that function as antioxidants include vitamin C, beta carotene, vitamin E and selenium. And manganese, copper and zinc are constituents of superoxide dismutase, an enzyme that plays an important role in the body's antioxidant defense system.

The flavonoids are compounds that contain a particular structure called a flavone. They, like the carotenes, are color compounds and strong antioxidants. The flavonoids are widely distributed in plants, and include such compounds as quercetin (found in onions), rutin (buckwheat), the bioflavonoids (citrus fruits) and the isoflavones (soybeans).

Through the discovery of antioxidant compounds and how they work, science has provided a detailed explanation of yet another reason why whole foods are so good for us.

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.