Are Diet Coke and Diet Pepsi Bad For You?

A look into the controversial artificial sweetener aspartame

flickr - Family O'Abé
While FDA approved, there are a lot of concerns about the safety of diet drinks containing aspartame.

Let’s just state the obvious first: whatever their nutritional value or health status, diet sodas are delicious. Sweet but not syrupy, with a slightly bitter aftertaste, we love everything from the shiny silver cans, the delightful Sofia Vergara Diet Pepsi ad or the cheeky-sweet "sexy gardener" Diet Coke ad. We consume plenty of diet soda ourselves, so we’d love to be able to report that diet sodas are 100 percent perfectly, unequivocally, ok for you.

Are Diet Coke and Diet Pepsi Bad For You? (Slideshow)

Sadly, the answer to the question "Are Diet Coke and Diet Pepsi bad for you?" is a little more complex than we’d like for it to be. There have been a huge variety of serious concerns raised about the health implications of aspartame, the popular sugar substitute used as the primary sweetener found in both of these sodas. Potential issues raised for both drinks include everything from brain tumors to cancers. 

The good news first: many of these concerns are unfounded. In fact, as of right now, the official stance on aspartame, according to both the European Food Safety Authority and the U.S . Food and Drug Administration is that aspartame has been studied at length and is safe for human consumption.

However, for anyone suffering from the genetic disorder phenylketonuria (frequently shortened to PKU), a component of aspartame called phenylalanine can cause really serious conditions such as brain damage, seizures, and mental retardation. Phenylalanine doesn’t just occur in diet drinks, though. It’s a natural part of many foods, including eggs, milk, and meat.

Aspartame is also considered unsafe for people who are taking certain medications, such as levodopa, neuroleptics, or monoamine oxidase inhibitors. If you’re taking a medication that you think may be contraindicated with aspartame, you should check with your doctor.

On the other hand, since they are sugar-free, Diet Coke and Diet Pepsi are options that are currently considered safe for people who have diabetes

Some have claimed that aspartame-laden drinks actually make people gain more weight. There has been some conflicting evidence on this, but it seems that diet drinks may not have the weight-loss effects that regular drinkers may have desired. It appears that in one study, rats gained the same amount of weight whether they were ingesting saccharin, aspartame, or sucrose (sugar-water).

Other studies have shown that weight-gain was promoted by the use of aspartame or saccharin as compared with sucrose, although it was suspected that this might have to do with less energy being expended and that the diet drinks may have encouraged fluid retention.

Other concerns have been raised about the general health effects of aspartame. Dr. Morando Soffritti, Director of the Ramazzini Institute in Bologna, Italy, has suggested  that the initial 1970s studies on aspartame showing that it was safe were deeply problematic. Since then, he claims, people have done better studies testing the long term potential of aspartame to cause cancer — and those studies suggest that there is genuine cause for concern. Soffritti has been doing active research on aspartame for some time. In 2006, he published a large-scale study on the long-term effects of aspartame based on his own research, and he has since urged reform for the way we evaluate aspartame's risks.

So there’s no short answer to the question "Are Diet Coke and Diet Pepsi Bad for You?" We can assert that these drinks probably won’t help you lose weight as much as we'd all like to think, and that if you suffer from PKU, you should avoid diet sodas. In terms of cancer, the scientific community seems to still be out on this one: there is plenty of contradictory evidence both ways. We're going to have to wait and see. And if you're like us risk-taking optimists, you might just do some of that waiting and seeing with a Diet Coke in hand.


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This sounds like when the tobacco industry said that tobacco products were not harmful. Any comment from the beverage industry should be looked at as a conflict of interest.


To be clear, diet beverages have been extensively studied and reviewed over decades – and repeatedly determined safe for consumption and enjoyment. Moreover, as this article notes, the European Food Safety Authority recently reaffirmed the safety of aspartame, declaring it safe for general consumption and pregnant women. This comprehensive risk assessment also found that aspartame does not cause cancer, harm the brain or nervous system or affect behavior or cognitive function in children or adults.

In addition, contrary to some of the claims made in this piece, studies show that diet soda and low-calorie sweeteners can be a useful tool in reducing calories in order to lose or manage a person’s weight. For instance, a randomized clinical trial published in the American Journal of Clinical Nutrition concluded that those who consumed diet beverages in place of caloric ones consumed fewer calories than other control groups, including those who consumed only water: Of course, it takes more than one-calorie swap to lose weight. Balancing total calorie consumption with physical activity is certainly key and within our control. Whereas other factors that impact weight gain, such as genetics and age, are outside our control.

The major takeaway here? Diet beverages are absolutely safe and can be part of a balanced diet and overall weight management plan. - Maureen Beach, American Beverage Association


This sounds like the tobacco companies saying that cigarette smoking was safe. any comment from someone in the beverage industry should be viewed as a conflict of interest.


I don't know about the sweeter being Bad but it triggers migraines for me along with MSG...I like the taste but I had to go back to sugar in my morning coffee..


Before you write all this GARBAGE, you need to do a "little" actual research and study so that you can know something about what you are trying to write about (unless of course you are just lying in order to deceive people into buying these POISONS) .


Given enough time researchers can find anything is bad for you.


What a stupid question, aside from water, if something doesn't have anything good for you in it, and it's got STUFF in it, it must be bad for you!

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