Diet Soda -- The Good, The Bad, The Thirsty

I DRANK A DIET COKE the other day, which usually makes me wonder if that's a dumb thing to do. For a long time I've felt a vague uneasiness about diet soft drinks, probably starting with the Fresca/cyclamates scare in the early '70s. Besides, I don't care much for the taste.

But I drank the Diet Coke because I was thirsty, it was cold and handy, and I wanted to avoid a few extra calories. And I thought, given that we consume so many diet soft drinks in this country, perhaps it's time to look into some common beliefs - pro and con - about them. Lending an ear and her expertise was Dr. Bonnie Worthington-Roberts, professor of nutrition at the University of Washington.

-- Is aspartame safe? I've heard about side effects from headaches to allergies to seizures. An entire book addresses the subject: "Aspartame (NutraSweet): Is It Safe?" by H.J. Roberts, M.D. But many of the book's arguments against aspartame are anecdotal.

Worthington-Roberts, who has read that book, says, "To my knowledge we have not seen any scientific data that should alarm us." She says a study by the Centers for Disease Control followed up on people who complained about aspartame side effects, and only a very small fraction reacted adversely. Her advice: "If it gives you a headache, don't eat it."

One exception, I hear: People with a genetic disorder called PKU, found in one in 15,000 babies born each year. Their systems aren't good at metabolizing one of the two amino acids that make up aspartame. Too much phenylalanine can damage their brains, which explains that warning on labels: "Phenylketonurics: contains phenylalanine."

-- Is there some problem related to calcium? Not really, Worthington-Roberts says, except that more children, girls especially, drink diet sodas instead of milk. Over 20 or 30 years, that can add up to a big dent in calcium intake, which is important for avoiding osteoporosis.

-- What about phosphorus and bone loss? Phosphoric acid is added to colas (diet and regular) for tartness. When the ratio of our intake of calcium and phosphorus is off - too much phosphorus, too little calcium - it may contribute to a loss of bone mass. Worthington-Roberts says that drinking a half-dozen diet pops a day might increase the risk among those already at high risk (female, thin frame, no exercise, family history of osteoporosis). But the studies have been only in animals.

-- Is the caffeine a problem? For probably 90 out of 100 people, no. The other 10 may be truly addicted, suffering headaches and other withdrawal symptoms if they stop or cut back. They might want to quit, or not. "It's your choice."

-- What about the carbonation? Not unless it's, well, a problem. "It's a gas, and so it's a source of gas production."

-- Can we count diet sodas toward the 8 to 10 glasses of fluids we're supposed to drink each day? Yes, Worthington-Roberts says, unless we're recovering from an illness (such as flu or diarrhea) or hard workouts. In those cases, we might have an electrolyte imbalance, which could be helped with sports drinks or simply a common-sense diet.

-- As alternatives to sugary drinks, do diet sodas help prevent cavities? Not likely, she says. Fluoride and better dental care get the credit for this country's big drop in cavities. Sweet liquids tend to pass quickly through the mouth, not posing much of a threat to teeth.

-- Do diet soft drinks keep us from gaining weight? In our dreams. People who save calories by drinking diet sodas tend to make up for it somewhere else. ("I'll have a Diet 7-Up - and the cheesecake.") As we've been gulping down ever more diet sodas, as a nation we've been getting fatter, not thinner. Not even holding our own.

Besides, if we crave sweets but eat fake sweets, our bodies can tell the difference. And they may not let up until we eat the real thing, Worthington-Roberts says: "The body is not dumb."

Molly Martin (464-8243) is assistant editor of Pacific Magazine.

Shared Incentive: Last call for any of you who want to share your fitness progress in the past nine months - I need your short summary by March 8. Send with your name, address and phone number to Shared Incentive, Pacific Magazine, Seattle Times, P.O. Box 70, Seattle, WA 98111, or e-mail mmar-new@seatimes.com ----------------------------------------------------------------- NOTEBOOK

Today's fitness

"Seven days without P.E. makes one weak," says the bottom of one month's "Calendar Calisthenics," a program used by more than 16,000 students in Seattle's elementary and middle schools, and catching on elsewhere. Calendars posted on home refrigerators invite children - and their families - to check off one activity-related task each day, from "Challenge your family to a one-foot balance-for-time contest" to "Work on spinning a ball on your finger" to "Find out what foods you consumed today contain vitamins A, B and C." For information, call Bud Turner at Seattle Public Schools, 298-7985.

Asthma and your doctor

Time with your doctor can be all too brief, and sometimes it's hard to remember everything you intended to discuss. For people with asthma, now there's a guidebook and chart to help monitor symptoms and share that information at your next appointment. "Making the Most of Your Next Doctor Visit" is free from 1-800-456-2784.

Grazing

In my quest for portable, low-fat snacks that aren't mostly sugar, local sausage king Oberto scored some points with Turkey Jerky. Made from strips of turkey breast, it contains 80 calories and one-half gram of fat per 1-ounce serving. I prefer the natural and pepper flavors over the sweeter teriyaki. One wish: that it was available in 1-ounce packages like its beef counterpart, instead of the 4-ounce bags that cost $4.99 or more. At Costco and supermarkets.