The Distinction Between Soluble, Insoluble Fiber

Question: I know that eating fiber is important, but I’m confused about the differences between soluble and insoluble fiber and the health benefits of each.

--PATRICIA O’CONNOR

Answer: Soluble fiber, the type found in oat bran and fruit (pectin is one of the most well-known of the soluble fibers), dissolves to become viscous. This fiber is often used in low-fat and nonfat foods to add texture and “mouth feel.” Such fiber is not actually digested but binds to fatty substances and promotes their excretion as waste, which can lower blood cholesterol levels.

Insoluble fiber, or “roughage,” such as cellulose, gives structure to plant cell walls. Wheat bran is an insoluble fiber. This fiber helps move waste through our digestive tracts, helping prevent constipation, but is also not digested.

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Q: With all the power failures and brownouts, I’m concerned about which foods in my refrigerator I can eat and which ones I should throw away. Any suggestions?

--LYNE GRILLO

A: The best suggestion is to add six or eight picnic-type cold packs to your freezer and keep them there. In the event of a power failure, place the freezer packs next to the most perishable foods in the refrigerator compartment, and keep the refrigerator and freezer doors otherwise closed. Unopened, most modern refrigerators will stay cold at least four to six hours; adding freezer packs can extend that time. Frozen foods, if the door remains closed, can safely last a day or two. Discard any foods that are highly perishable--such as meats, dairy products, leftovers, mayonnaise and desserts--that have been at room temperature for more than two hours. Fresh fruits and vegetables, hard and processed cheeses, condiments and butter will usually last up to five hours at room temperature. Not all foods that are spoiled smell bad, but all foods that smell bad are spoiled. If there is any question about an individual food’s safety, don’t take a chance--throw it out.

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Phil Lempert is the food correspondent for NBC’s “Today” show. He welcomes questions about healthful food shopping but regrets that he cannot respond to every query. He can be reached at plempert@@aol.com or, by mail, at Before You Bite, Los Angeles Times’ Health section, 202 W. 1st St., Los Angeles, CA 90012.