For those who enjoy the occasional diet soda, particularly Diet Dr. Pepper or diet root beer, but want to avoid aspartame, finding suitable alternatives can be a challenge. Many people dislike the taste of other diet sodas and are looking for options sweetened with Splenda or Stevia that are also gluten-free.
Understanding the Concerns with Aspartame and Other Sweeteners
There are concerns about the safety of aspartame, with some studies suggesting potential links to cancer and neurotoxic effects. The FDA has regulated aspartame since 1974 and approved it as a general-purpose sweetener in 1996. The acceptable daily intake for aspartame established by the FDA is 50 milligrams (mg) per kilogram (kg) of body weight per day. A 12-ounce can of diet soda contains about 200 mg of aspartame, so based on these guidelines, a person weighing about 150 pounds (or 68 kg) could drink around 17 cans of diet soda per day.
In July 2023, the World Health Organization (WHO) reclassified aspartame as “possibly carcinogenic to humans” based on limited evidence. Even so, the WHO still advises that 40 mg/kg of body weight is a safe amount of aspartame to consume per day. The FDA disagrees that the limited evidence points to human cancer risk, citing research that found no link between low- and no-calorie sweeteners and beverages and increased cancer risk in humans.
More recent studies are mixed in their conclusions, too. A data-mining analysis published in 2025 determined that artificial sweeteners, including aspartame, might potentially increase the incidence of kidney cancer, low-grade glioma, breast cancer, and prostate cancer. The study’s researchers “strongly advise the public to reduce their intake of artificial sweeteners to alleviate common health issues such as cardiovascular disease, diabetes, and irritable bowel syndrome.” Yet another study published in 2025 found no association between aspartame consumption and invasive breast cancer risk.
Splenda is another artificial sweetener that is also a potential concern. According to some doctors, if you have GI problems, use of Splenda is not recommended, as it can cause stomach pain and other issues.
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Brands Using Splenda
Boylan's diet sodas use Splenda, and they offer a diet root beer option. These sodas often come in glass bottles.
Brands Using Stevia
There are newer sodas made with Stevia, which is often recommended as a sweetener. Blue Sky offers a stevia soda. Zevia Root Beer uses stevia, but the flavors of root beer are all but smothered in sweetener, giving it an unappealing flavor reminiscent of chemicals.
Root Beer Brand Reviews
Tasting the root beers was both fun and surprising, as the flavor profiles of the beloved drink can be vastly different. Some are creamy and vanilla-forward, while others lean into cinnamon, anise and cherry. Some are deep brown and extra foamy; others are clear with hardly any bubbles at all.
Achieving exactly the right level of sweetness is clearly a challenge, as many brands don’t get it right. Some rely on a single sweetener such as aspartame, stevia or Sucralose. But the most successful incorporate several sweeteners, using them to create a careful balance.
- Mug Root Beer: The signature sweetness of full-sugar root beer plus a nice hit of traditional root beer flavor makes this just plain terrific. It’s a gulp of childhood so good, it’s hard to believe it has no sugar.
- Stewart’s Diet Root Beer: Those who like a slightly less sweet soda may fall hard for this rich, caramelly version. Sweetened with aspartame, it’s refreshing and has loads of interesting flavors.
- A & W Zero Root Beer: A pleasant hit of vanilla, extra-smooth flavor and lots of root beer froth explain why this brand earns a spot on every soda aisle. It’s good.
- Barq’s Zero Sugar Root Beer: It’s not awful, but this pour is significantly less flavorful than the top contenders. The use of aspartame as the primary sweetener is a good choice, but it’s extremely sweet and lacks both aroma and flavor.
- Olipop Classic Root Beer: Fans of kombucha may enjoy this unusual, creamy flavored root beer made from a wide array of botanicals. It’s minimally sweet and has a distinct sour note thanks to a dose of prebiotics and a hit of cider vinegar. 35 calories.
- Zevia Root Beer: There’s a right way and a wrong way to use stevia. This brand gets it wrong, as the flavors of root beer are all but smothered in sweetener, giving it an unappealing flavor reminiscent of chemicals.
- Poppi Root Beer: Infusing a soda with gut-enhancing ingredients is a great idea, but the tart kick of prebiotics makes this taste more like cola than root beer. 25 calories.
- Virgil’s Zero Root Beer: This insipid, sour liquid has little flavor and no fizz.
Diet Stewart’s is the best diet root beer we tasted-it has tons of extremely small bubbles, a nice, spiced cinnamon or nutmeg quality, and it doesn’t taste like fake sweetener at all. It’s actually a bit on the dryer end of the spectrum, which is surprising for a diet root beer. Often, fake sweeteners come off tasting way sweeter than actual sugar.
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Exploring Homemade Options
Making your own root beer can be a way to control the ingredients and sweeteners used. You can use sparkling water and juice or add Stevia to homemade soda.
Considering Other Beverages
If you are having gastrointestinal issues, it might be worth it to cut out soda all together. Unsweetened fruit teas are a good alternative. You can make jugs of iced tea at home and carry it around in a cold metal thermos. It's delicious, has no calories, and no extra sweeteners.
Gluten-Free Considerations
Coke should be out of the question for a number of reasons, but mostly because of the Carmel Coloring, as far as I know it still contains gluten.
Read also: Weight Loss with Low-FODMAP