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Dr. Jacqueline Gerhart: Is diet soda bad for you?

UW Health Family Medicine physician Dr. Jacqueline GerhartMadison, Wisconsin - UW Health Family Medicine physician Jacqueline Gerhart writes a column that appears Tuesdays on and in the Wisconsin State Journal. Columns are re-published here with permission.


"Is diet soda really bad for you? Friends tell me this all the time but since I drink soda that has no calories and no caffeine I can't see what's wrong with it."


Our society seems to run on sugar. Much of this comes from soft drinks (termed "soda" or "pop" depending on what region of the country — or the state — you live in). Our country produces 10.4 billion gallons of soft drinks each year. That's enough to serve every American a 12-ounce can every day, 365 days a year.


In trying to get my patients to improve their health, I always recommend that they decrease the amount of sugar they eat, and cut down on the soft drinks. The initial switch to diet soda from regular soda (assuming you don't change your calorie intake or exercise level), should decrease your weight. But do diet beverages keep the weight off? Are they healthy for you?


A recent study published in the New England Journal of Medicine addresses whether we should think more about food type rather than just reducing calories. The study looked at more than 100,000 healthy, non-obese individuals, and monitored the types of food they ate, regardless of the calories they took in. The study showed that weight gain was most associated with potato chips, potatoes, sugar-sweetened beverages, unprocessed red meats, and processed meats, whereas vegetables, whole grains, fruits, nuts, and yogurt consistently decreased weight. It also studied diet soda. They found no difference in weight between those who drank diet soda and those who did not. In other words, it wasn't shown that people either lose or gain weight on diet soda long-term.


There is some evidence against diet soda. A study from Purdue University showed that rats eating food sweetened with saccharin took in more calories and gained more weight than rats fed sugar. Another study in San Antonio showed that those who averaged three or more artificially sweetened beverages a day were more likely to have gained weight over an eight-year period than those who didn't drink artificially sweetened beverages. A study from the University of California-San Diego compared MRI brain images of humans that took small sips of sugar water with those who sipped sucralose water. Sugar activated the "food reward centers" of the brain while sucralose did not. This could mean that you may not feel as satisfied when you consume artificially sweetened foods and beverages. In addition, there is some evidence that certain sweeteners can lead to kidney abnormalities or changes in your electrolytes.


On the positive side of things, diet beverages are less caloric, and give you less sugar. While sugar-sweetened beverages increase one's risk for diabetes, diet beverages have not been linked nearly as consistently. Some studies hint that the sweetener stevia may have added benefit for patients with hypertension or diabetes. Also, the FDA has approved aspartame (Equal, NutraSweet), saccharin (Sweet'N Low), and sucralose (Splenda), and stevia was deemed "generally recognized as safe" in 2009.


So, if your diet soda is replacing your regular sugar-filled soda habit, then you are likely decreasing your chances of diabetes. But, if it is your daily drink of choice, I would suggest putting down the can, bottle, or 48-oz mega cup, and picking up a glass of good old-fashioned water.


Here's to your health!



This column provides general health information and is not specific advice intended for any particular individual(s). It is not a professional medical opinion or a diagnosis. Always consult your personal health care provider about your concerns. No ongoing relationship of any sort (including but not limited to any form of professional relationship) is implied or offered by Dr. Gerhart to people submitting questions.


Date Published: 11/29/2011

News tag(s):  jacqueline l gerhart

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