Sometimes you want a drink with more pizzazz than water, so you might turn to diet soda.
But with reports about the potential dangers of aspartame, a sugar substitute in many diet sodas, you might want to avoid the fizzy drink. And if you have a rare hereditary disorder known as phenylketonuria (PKU), you likely need to avoid it, since you have to limit your intake of phenylalanine, which is found in aspartame.
Though they might be harder to find, some diet sodas do not contain aspartame. Read on to learn what exactly aspartame is, whether it’s safe to consume, and which diet sodas to turn to if you’d like to avoid it.
What Is Aspartame?
Aspartame is a sugar substitute that’s about 200 times sweeter than sugar, though it contains 4 calories per gram — the same amount as in sugar. But because far less aspartame is needed to achieve sweetness, it adds fewer calories to food.
Aspartame may be found in soft drinks like diet soda, as well as in some products labeled “sugar-free” or “no-sugar.” These might include breakfast cereals, baked goods, chewing gum, juice, candy, ice cream, yogurt, and packaged snacks and desserts.
The sugar substitute is made through the chemical fusion of two naturally occurring amino acids: aspartic acid and phenylalanine. You might see it under the brand names Equal, Nutrasweet, or Sugar Twin.
Diet Soda Without Aspartame
Reduced and no-sugar versions of drinks can give you a way to cut back on sugar without having to give up the beverages you enjoy.
So if you’re looking for aspartame-free diet soda, you might start to feel like you don’t have any options.
Yet other lesser-known soda manufacturers do offer aspartame-free sodas that can satisfy your desire for a bubbly drink without the artificial sweetener.
Zevia, for example, uses stevia leaf extract to sweeten all of its no-calorie soda products. Flavors include traditional cola and vanilla cola but also fruit options such as cherry or orange, as well as ginger, root beer, and cream varieties.
Whole Foods Market also makes a Zero Calorie Cola sweetened with stevia leaf extract.
And although it isn’t zero calories and does contain 2 grams of added sugar, Olipop’s Vintage Cola drink also uses apple juice concentrate and stevia leaf extract as a sweetener. Plus, it’s a prebiotic soda, which means it contains fiber that helps keep your gut bacteria healthy.
You could also try switching from diet soda to a zero-calorie sparkling water, which will give you all the fizz you love without any sweeteners. Most sparkling waters from Aura Bora, for example, are made with only water, herbal extracts, and natural flavors.
Is Aspartame Safe?
The U.S. Food and Drug Administration (FDA) has regulated the use of 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.
But aspartame is not safe for people with the hereditary disorder PKU, which causes phenylalanine to build up in the body. For this reason, people with PKU have to strictly limit their phenylalanine intake and should always choose diet drinks without aspartame.
Researchers and consumers have worried about a possible link between aspartame and cancer for decades as well.
In fact, 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.
Along with the study of aspartame’s potential cancer risks, more research is needed on other potential health concerns of the sugar substitute.
In a review of 29 studies, researchers linked aspartame with neurotoxic effects, such as behavioral concerns, mood disorders, and memory and learning impairments. (It’s important to note that some of the studies occurred in humans, while others took place in animals, so it isn’t entirely clear how those effects would translate to humans.)
Older research also associated aspartame with behavioral and cognitive problems — such as headaches, irritable mood, depression, and insomnia. The researchers advise approaching aspartame with caution and note that more research about the effects of aspartame on brain health is needed.
In another study done in animals, researchers identified a possible association of aspartame and an increased risk of cardiovascular disease and worsening of atherosclerosis.
Overall, more high-quality research involving humans is needed on sweeteners like aspartame to affirm their safety or identify any risks.
Takeaway
Aspartame is a common artificial sweetener found in most diet sodas, but recent health concerns, including potential cancer risks, have led some people to seek alternatives.
If you’re trying to cut aspartame from your diet, try a lesser-known soda brand like Zevia that uses stevia leaf extract as a sweetener instead.
You can also try swapping out soda for zero-calorie sugar-free sparkling water to get the same great fizz without any sweeteners.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Xie J et al. An Integrative Analysis Reveals Cancer Risk Associated With Artificial Sweeteners. Journal of Translational Medicine. January 2025.
Romanos-Nanclares A et al. Consumption of Aspartame and Risk of Breast Cancer in the Nurses’ Health Studies. Journal of the National Cancer Institute. April 2025.
Fogel MN et al. Aspartame and Its Potential Neurocognitive Effects in Humans. Nutrition Reviews. July 3, 2025.
Choudhary AK et al. Neurophysiological Symptoms and Aspartame: What Is the Connection? Nutritional Neuroscience. June 2018.
Wu W et al. Sweetener Aspartame Aggravates Atherosclerosis Through Insulin-Triggered Inflammation. Cell Metabolism. May 2025.
Julie Cunningham has been a registered dietitian for more than 25 years. She is a certified diabetes care and education specialist (CDCES) and an international board-certified lactation consultant. She has served as the president of the Foothills Chapter of the North Carolina Dietetics Association (NCDA) and has been a member of the executive board of the NCDA.
Ms. Cunningham received a bachelor's degree from Appalachian State University in North Carolina. She subsequently completed a master's degree in public health nutrition at the University of North Carolina at Chapel Hill.
Ms. Cunningham has worked in women's and children's health, cardiology, and diabetes. She is the author of 30 Days to Tame Type 2 Diabetes, and she has also written for Abbott Nutrition News, Edgepark Medical Health Insights, diaTribe, Babylist, and others.
A resident of beautiful western North Carolina, Cunningham is an avid reader who enjoys yoga, travel, and all things chocolate.
Andrea Boldt has been in the fitness industry for more than 20 years. A personal trainer, run coach, group fitness instructor and master yoga teacher, she also holds certifications in holistic and fitness nutrition.
