Diet soda may do more harm than good

 Diet soda drinkers have the same health issues as those who drink regular soda, according to a report published Wednesday.

Purdue University researchers reviewed a dozen studies published in the past five years that examined the relationship between consuming diet soda and health outcomes for the report, published as an opinion piece in the journal Trends in Endocrinology & Metabolism. They say they were "shocked" by the results.

"Honestly, I thought that diet soda would be marginally better compared to regular soda in terms of health," said Susan Swithers, the author of this opinion piece and a behavioral neuroscientist and professor of psychological sciences. "But in reality, it has a counterintuitive effect."

Stop drinking soda, for (your own) good

Artificial sweeteners in diet soda fulfill a person's craving for a sweet taste without the calories. But that's the problem, according to researchers. Think of it like crying wolf.

Fake sugar teases your body by pretending to give it real food. But when your body doesn't get the things it expects to get, it becomes confused on how to respond.

"You've messed up the whole system, so when you consume real sugar, your body doesn't know if it should try to process it because it's been tricked by the fake sugar so many times," Swithers said.

On a physiological level, this means when diet soda drinkers consume real sugar, the body doesn't release the hormone that regulates blood sugar and blood pressure.

Diet soda drinkers also tend to pack on more pounds than those who don't, the report says.

 

"The taste of sweet does cause the release of insulin, which lowers blood sugar, and if carbohydrates are not consumed, it causes a drop in blood sugar, which triggers hunger and cravings for sugar," said CNN diet and fitness expert Dr. Melina Jampolis.

The artificial sweeteners also dampen the "reward center" in your brain, which may lead you to indulge more calorie-rich, sweet-tasting food, according to the report.

The American Beverage Association says the report was "an opinion piece, not a scientific study."

Health effects of artificial sweeteners

"Low-calorie sweeteners are some of the most studied and reviewed ingredients in the food supply today," the association said in a statement. "They are safe and an effective tool in weight loss and weight management, according to decades of scientific research and regulatory agencies around the globe."

Diet soda's negative effects are not just linked to weight gain, however, the report says.

It found that diet soda drinkers who maintained a healthy weight range still had a significantly increased risk of the top three killers in the United States: diabetes, heart disease and stroke.

"We've gotten to a place where it is normal to drink diet soda because people have the false impression that it is healthier than indulging in a regular soda," Swithers said. "But research is now very clear that we need to also be mindful of how much fake sugar they are consuming."

There are five FDA-approved artificial sweeteners: acesulfame potassium (Sunett, Sweet One), aspartame (Equal, NutraSweet), neotame, saccharin (SugarTwin, Sweet'N Low) and sucralose (Splenda).

All of them are chemicals. "Saccharin was one of the first commercially available artificially sweeteners, and it's actually a derivative of tar," Swithers said.

Natural sweeteners like Stevia -- which has no calories and is 250 times sweeter than regular sugar -- are not a chemical but are still a processed extract of a natural plant and increase your health risks similar to artificial sweeteners.

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"Just because something is natural does not always mean that it is safer," Jampolis said.

There more studies and research that need to be done, but in the meantime, experts say, limit consumption.

"No one is saying cut it out completely," Swithers said. "But diet soda should be a treat or indulgence just like your favorite candy, not an everyday thing."

 

Aspartame is a common sugar substitute used as a sweetener in many prepared foods and beverages, particularly diet soda. It is a common choice for those trying to lose weight, as it lowers the number of calories in food. However, new research suggests the sweetener may be ineffective for weight loss, and it may even have the opposite effect.

Researchers suggest a sweetener commonly used in diet soda may cause weight gain.

Some research indicates that even acceptable daily intakes of aspartame, as regulated by the United States Food and Drug Administration (FDA), might make you hungrier and lead to weight gain.
Other studies in rodents have shown that compared with sugar, sweeteners like saccharin and aspartame causes weight gain instead of weight loss.
Reasons why this may happen are not entirely clear, but a team of researchers from the Massachusetts General Hospital decided to investigate why aspartame does not promote weight loss.
Their research - published in the journal Applied Physiology, Nutrition and Metabolism. - suggests one of aspartame's metabolites may play a role.
The researchers were led by Dr. Richard Hodin, from the Massachusetts General Hospital Department of Surgery.

Studying aspartame intake in mice

One of the breakdown products of aspartame is phenylalanine, an inhibitor of a gut enzyme called intestinal alkaline phosphatase (IAP) that has been shown to prevent metabolic syndrome in mice.
Metabolic syndrome is a generic name given to a group symptoms associated with type 2 diabetes, cardiovascular disease, and obesity.
Dr. Hodin and team had conducted previous research where they fed IAP to mice that were on a high-fat diet. They found that IAP can prevent the onset of metabolic syndrome, as well as reduce the symptoms in animals that already had the condition.
Based on this known relationship between IAP, phenylalanine, and aspartame, researchers hypothesized that consuming aspartame may promote metabolic syndrome because of its inhibition of phenylalanine.
For the study, researchers added aspartame to diet and regular soda, before measuring IAP activity in mice.
The scientists used four groups of mice. Two groups were put on a normal diet, with one group receiving drinking water with aspartame and the other just plain water. The other two groups were put on a high-fat diet, with one group getting plain water and the other getting water with aspartame.
The normal-diet group that received aspartame consumed the equivalent of 3 ½ cans of diet soda every day. The group that was on a high-fat diet received aspartame in doses the equivalent to almost two cans of diet soda.
The mice were monitored for 18 weeks.

Aspartame does not help with weight loss

Dr. Hodin and team found that IAP activity was reduced when it was added to a drink containing aspartame, but IAP levels remained the same when IAP was added to a drink containing sugar.
Researchers injected aspartame into the mice's small intestines, where IAP is normally produced. They found this reduced IAP levels.
Researchers also injected saline solution in bowel segments, but IAP activity remained the same.
At the end of the 18-week period, there was no significant difference between the weights of the two groups that were fed a regular diet.
However, mice on a high-fat diet that received aspartame gained more weight than mice that did not receive aspartame.
Mice that received the sweetener also had higher blood sugar than those without aspartame.
They also had higher levels of the TNF-alpha inflammatory protein in their blood, which is usually associated with metabolic syndrome.
"Sugar substitutes like aspartame are designed to promote weight loss and decrease the incidence of metabolic syndrome, but a number of clinical and epidemiologic studies have suggested that these products don't work very well and may actually make things worse," says Dr. Hodin.

Aspartame blocks enzyme that prevents obesity

Inside the human body, aspartame is metabolized and broken down into phenylalanine, aspartic acid, and methanol. Phenylalanine and aspartic acid are amino acids that are naturally present in many protein-containing foods.
However, phenylalanine inhibits the production of IAP.
"We think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP," Dr. Hodin says.

"People do not really understand why these artificial sweeteners don't work. There has been some evidence that they actually can make you more hungry and may be associated with increased calorie consumption. Our findings regarding aspartame's inhibition of IAP may help explain why the use of aspartame is counterproductive."

Dr. Richard Hodin

While the researchers admit that other contributing factors may play a role, Dr. Hodin emphasizes that the findings "clearly show that aspartame blocks IAP activity, independent of other effects."