Diet soda has become a ubiquitous beverage for individuals seeking to reduce their sugar and calorie intake. Since the debut of No-Cal Beverage ginger ale in Canada in 1952 and the subsequent release of the first diet cola seven years later, food manufacturers and consumers have been drawn to the idea of a low-calorie alternative to traditional sugary sodas. The premise is simple: replace the high-calorie sugars with non-caloric sweeteners and potentially observe significant improvements in weight management and overall health. This article delves into the ingredients commonly found in diet sodas, explores their potential health effects, and considers alternatives to this popular beverage.
The Rise of Diet Soda
The consumption of diet soda experienced a notable increase in the early 2000s. From the 1990s into 2002, diet soda consumption was stable but started to increase in 2002, rising from 4.8 ounces per person per day to 5.6 ounces in 2004. Today, a significant portion of the American population consumes diet products, including low-calorie, reduced-sugar, or sugar-free foods and beverages.
Diet Coke: A Case Study in Ingredients
To understand what exactly goes into a diet soda, let's take a closer look at the ingredients of Diet Coke:
Carbonated Water
This is water dissolved with carbon dioxide. Poof, we have carbonic acid. Without this, cola wouldn’t be brown and happy hour beers wouldn’t be gold. Carbonated water provides the fizz and slight acidity characteristic of soda.
Caramel Color
Caramel color is the most commonly consumed food coloring ingredient in the world. It provides no flavor, only color. It’s produced by heating carbohydrates (like fructose, dextrose, or invert sugar) with a food-grade acid (like sulfuric, phosphoric, or citric) to break the sugar bonds. Or the carbohydrates can be heated along with salts (like ammonium, sodium, and bicarbonate). Polyglycerol esters of fatty acids are also used as anti-foaming agents during the production of caramel color. Think of caramel color as burnt sugar. It’s the most widely used food coloring, imparting the signature brown hue to cola. While generally considered safe, with negative health consequences of caramel color unlikely as long as someone doesn’t consume more than 200 mg/kg of body weight, there is the potential of an allergic reaction, but that comes with many food ingredients. Caramel color has a very low caloric content, and most of it is not absorbed in the gastrointestinal tract.
Read also: Can You Drink Diet Soda While Fasting?
Aspartame
Aspartame, an artificial sweetener that’s composed of aspartic acid, phenylalanine and a methyl ester, is a chemical, not a naturally occurring compound. It was discovered in 1965 by a chemist named G.D. Searle. (See our Research Review on Splenda for more on the discovery of artificial sweeteners.) He was actually studying a treatment for gastric ulcers at the time. 16 years later, aspartame received limited sanction, and in 1983 was approved for use in diet sodas. food industry (as of 2007). With more than 90 countries having approved aspartame, its use is widespread. This artificial sweetener is a cornerstone of many diet sodas. Aspartame exceeds table sugar sweetness by 200 times. Since it still contains 4 calories per gram (as does table sugar), this intense sweetness allows much less of it to be used in diet sodas. The major vehicle for aspartame consumption in North America is diet soda. and 40 mg/kg in Europe and Canada. For an 80 kg person, this is between 3,200 and 4,000 mg per day. After we swallow a gulp of diet soda, aspartame makes its way to our small intestine, where it’s broken down into its components: aspartic acid, phenylalanine and methanol. These substances can then enter the blood. Methanol is further metabolized into formaldehyde and formic acid. But before you call the poison control center, remember that we also get methanol from figs and orange juice (along with other foods), and we get formaldehyde from scary substances like apples, carrots and coffee. Hope you covered the kid’s eyes for that one. However, its safety has been a subject of debate and research. Research in animals provides evidence that aspartame has a strong cancer causing and brain damage potential, with the dosage tested approximated at the ADI for humans. In 2007 and 2008, scientists confirmed and reinforced aspartame’s varied cancer causing potential at a dose level close to the amount suggested for humans. Moreover, when exposure begins during fetal life, the chances of cancer are enhanced. There was a 98 page review about aspartame in a 2007 Critical Reviews of Toxicology (published shortly before the aforementioned research was released). The review indicates that the more aspartame we consume, the greater potential for health to go awry. In saying that, the authors concluded that no credible link exists between consumption of aspartame (at levels estimated in the human diet) and conditions related to the nervous system and behavior. Aspartame has 92 side effects listed by the FDA and use by pregnant women and young children is discouraged.
Phosphoric Acid
This stuff has a tangy, sour taste and slows the growth of mold and bacteria. It’s a bit different from straight phosphorus as it binds with magnesium and calcium in the digestive tract to form salts that aren’t absorbed. This may lead to a decline in the materials needed for bone deposition. So as you might assume, studies have associated phosphoric acid consumption to a lower bone density. Diet colas, which generally contain phosphoric acid (non-colas usually don’t), have also been linked to kidney disease and kidney stones. Two or more colas per day more than doubled the incidence of kidney disease in one study; non-colas didn’t have the association. This acid contributes to the tangy flavor of colas and acts as a preservative.
Potassium Benzoate
This stuff is a preservative and discourages the growth of yeast, mold and bacteria. It has minimal taste and risk for toxicity. Unfortunately, along with ascorbic acid (vitamin C), potassium benzoate can form benzene. Benzene is a known carcinogen. Sodium benzoate is also used in some diet sodas, but since most people don’t want the extra sodium, manufacturers are using it less. It serves as a preservative, inhibiting the growth of microbes.
Natural Flavors
Well, the magical natural flavor used to be saskra root in diet coke, but that plant is now extinct. With that being said, natural flavors can include countless items. Thank you for contacting The Coca-Cola Company, Mr. Andrews. As you may know, flavor formulations are very valuable proprietary information, therefore we do not discuss the blend of flavoring materials used in Coca-Cola brand products. Food and Drug Administration (FDA) regulates the substances that can be labeled as flavors, whether natural or artificial, and we strictly adhere to all such guidelines. We hope this information is helpful. This is a broad category encompassing a variety of flavorings derived from natural sources.
Citric Acid
More than half of all citric acid is produced in China. It acts as a preservative and provides a sour taste. Too much of it can erode tooth enamel. While it does exist naturally in citrus fruits, this isn’t where most “food grade” citric acid comes from. Actually, cultures of something called Aspergillus niger are fed on a sugar containing medium to produce it. It enhances the sourness and acts as a preservative.
Read also: The Hoxsey Diet
Caffeine
Caffeine is the most widely consumed stimulant in the world and occurs naturally among several plants such as coffee bean, kola nut, tea leaf, and cacao seed. (See our article All About Caffeine, available to PN community members.) Caffeine is a methylxanthine. Other common methylxanthines include theobromine and theophylline, which are found in cocoa and teas. Methylxanthines act as adenosine receptor blockers and phosphodiesterase inhibitors. If you have no idea what I just said, here’s some further explanation. Adenosine acts as the “brakes” in the central nervous system. Caffeine is actually one of the most widely studied, and most effective, ergogenic acids on the planet. This stimulant is added for its energizing effects.
Health Concerns and Controversies
Aspartame and Cancer
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.
Other Potential Health Concerns
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.
Metabolic Syndrome and Diabetes Risk
There is also an association between diet soda consumption and the development of metabolic syndrome. It’s only an association and other factors might come into play (notably, endless rounds of X-Box and Tastycake benders). To be more specific, it’s not a direct “cause-and-effect” relationship. A meta-analysis published in Frontiers in Nutrition observed a significant association between artificially sweetened beverages (ASBs) and an increased risk of type 2 diabetes, with a pooled relative risk (RR) of 1.32 (95% CI: 1.11, 1.56).Another study that suggests increased diabetes risk with diet soft drinks was published in 2015 which interestingly suggested a higher risk of diabetes with diet soft drinks compared to sugared soft drinks. There are several possible explanations for the counter-intuitive weight gain and increased diabetes risk with the so called diet sodas.
Dental Health
Too much of citric acid can erode tooth enamel.
Read also: Walnut Keto Guide
Alternative Sweeteners and Diet Soda Formulations
Sucralose and Acesulfame Potassium
Recently, two other sweeteners have been used with increasing frequency: sucralose (marketed as Splenda) and acesulfame potassium ("Sunett" or "Ace K"). The K in "Ace K" represents the chemical symbol for potassium. Acesulfame potassium is usually combined with aspartame, sucralose, or saccharin rather than alone and its use is particularly common among smaller beverage producers (e.g. Big Red). Advocates say drinks employing these sweeteners have a more natural sugar-like taste than those made just with aspartame, and do not have a strong aftertaste. The newer aspartame-free drinks can also be safely consumed by phenylketonurics, because they do not contain phenylalanine.
Stevia
One study investigated the electrochemical properties of stevia rebaudiana, a herb with potential as a glucose sugar alternative. By using a cyclic voltammetric technique with a nano-sensor modified glassy carbon electrode, the limited safety dose was determined as 0.4 mM (28 mg/mL), where the stevia compound acted as an anti-oxidative sweetener. Initially launched in Argentina in 2013, Coca-Cola Life is made with a mix of stevia and sugar as its sweeteners.
Reduced-Calorie Colas
In an effort to profit on the surging popularity of low-carbohydrate diets, Coca-Cola and PepsiCo both released reduced-calorie versions of their flagship colas in 2004. The products contain approximately half the sugar of the regular versions. The Pepsi variant, Pepsi Edge, is sweetened with sucralose and corn syrup. The sweetening of the Coca-Cola variant, Coca-Cola C2, is a combination of corn syrup, aspartame, acesulfame potassium and sucralose. Pepsi discontinued Edge in 2005, citing lackluster sales. Coca-Cola soon followed suit. Half of the sugar of a can of regular cola still exceeds the daily sugar allowance of some popular low-carbohydrate diets.
The Broader Perspective
Those who tend to overeat seem to use a greater amount of artificial sweeteners and diet sodas. This may reflect some ability of artificial sweeteners to actually stimulate overeating, possibly through enhancing appetite and/or disrupting learned associations between sweet taste and caloric density of food. Remember, we get used to sweet tastes. Diet sodas provide an extremely sweet sensation that may deter from the enjoyment of unprocessed/naturally sweet foods. Can aspartame help control blood sugar responses? Well, the results are mixed. One study on patients with type 2 diabetes showed an aspartame rich breakfast (real life translation: 2 diet cokes from 7-11) induced a similar rise in glucose and insulin levels.
Alternatives to Diet Soda
So what’s the alternative to diet soda? Well, sugar intake from regular soda can create an environment in the body that leads to more stored body fat. Instead of thinking about how much a food or drink can harm our health, I like to consider how much a food or drink could actually improve our health. Thinking of diet soda in that regard can help clear things up. Now, while it hasn’t been “proven” that diet soda is the final blow to someone’s health status, we do know consuming diet soda regularly doesn’t do much to improve health. Does the body know how to handle concentrated levels of phosphoric and citric acid? Does the body know how to handle concentrated levels of artificial sweeteners like aspartame or sucralose? If someone passes on the diet soda, what would they be consuming instead? I’ve seen diet soda help people manage their weight and improve health. But I’ve also seen diet soda hinder people from managing their weight and impair health.
Economic Considerations
A person who drinks just 2 cans of soda a day will pay $206 over the course of a year to keep the habit going. If there is more than one soda drinker in the household, that yearly total could quickly double (or even triple). The bad news is that Diet Coke isn’t tax deductible.
Diet Soda Consumption Trends
According to a study by the National Center for Health Statistics, about one-fifth of the US population ages 2 years and over consumed diet drinks on a given day in 2009‒2010, and 11% consumed 16 fluid oz. of diet drinks or more. Overall, the percentage consuming diet drinks was higher among females compared with males. The percentage consuming diet drinks was similar for females and males at all ages except among 12- to 19-year-olds, where a higher percentage of females than males consumed diet drinks. A higher percentage of non-Hispanic white people consumed diet drinks compared with non-Hispanic black and Hispanic people.
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