DEAR DR. BLONZ: I must begin monitoring my intake of foods that raise my blood sugar level. Could you please provide some basic info about blood sugar? -- Y.M., Berkeley, California

DEAR Y.M.: A good way to begin is to think about rain -- a definite obsession here in Northern California. The rivers, lakes and even the water systems in our homes and towns are set to handle certain amounts of rain. A torrential downpour, or excessive rain on a regular basis, overwhelms the capacities of the various systems, and water ends up in places where it's not expected or desired. The end result, as we have seen in recent seasons, is flooding, property damage and injuries.

Similarly, the human body has various systems designed to handle an influx of carbohydrates.

Set aside the rain analogy for a moment. Glucose, a simple sugar, is the preferred fuel of the brain and the rest of the nervous system. It is an anaerobic fuel that releases energy without extra oxygen. It's what allows us to dash across the room to catch a falling object, or run to catch a bus without first needing to take several deep breaths to increase the level of oxygen in the bloodstream.

The body works best with a metered entry of glucose into the bloodstream, which happens when carbs come from a whole-grain starch and are part of a varied meal. After we eat complex carbohydrates, the digestive system breaks them down into simple sugars (mostly glucose) prior to absorption. After that, there are specific enzyme systems that work on the glucose to provide its unique benefits to the body.

Now back to the rain. With a normal downpour, the gutters on our houses and the drainage systems of our towns handle the water with little incident. But when you consume too much added sugar from sweets or sodas, especially on an empty stomach, it's like a deluge descending on your home.

When an excess of sugar enters the blood, the body has to scramble to assert control. Alternate pathways must be used, and if this occurs on a regular basis, the conditions become right for the development of our most troublesome diseases and conditions: heart disease, diabetes, diabetic neuropathies, obesity, hypertension, arthritis and even cancer. There is no way to sugarcoat the science.

Sugar is not bad in itself, but an excess of it tends to shove our bodies' systems in the wrong direction. A study in the Feb. 3 issue of JAMA Internal Medicine compared U.S. adults who consume no more than 10 percent of their calories from added sugar with those who have more. It reported that individuals who habitually consumed between 10 and 25 percent of their calories from added sugar had a 1.3 times higher risk of cardiovascular mortality. Those having 25 percent or more calories from added sugar had 2.75 times the risk of dying from cardiovascular disease.

Strive to keep your intake under control by opting for a diet that is primarily plant-based with a hefty percentage of whole foods. Read your labels, and pay specific attention to "added sugar" -- not the sugar naturally present in a whole food, but that which is purposefully added during processing. The FDA has proposed a revision of the Nutrition Facts label to include a specific listing of added sugars. I welcome this step forward.

Don't obsess over every gram; think big picture. This message is especially important for the growing bodies of children, teens and young adults.

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: 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.