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.