Diet Soda

Last Updated: September 28 2022

Carbonated sweet water with minimal calories. Diet sodas may be beneficial to a diet due to satiety effects and displacing sugared sodas, and their health effects should be seen as a sum of the parts like Energy Drinks. Not inherently healthy or unhealthy.

Diet Soda is most often used for

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    Components of Diet Soda

    Common ingredients or characteristics of Diet Soda that may influence health include:

    • Artificial sweeteners such as Aspartame
    • Sweetening enhancers like Acesulfame-Potassium
    • Coloring (of which caramel coloring is of interest for colas)
    • Caffeine content
    • Carbonation and General pH (acidity)

    Other ingredients may exist in certain diet sodas, and the label should be looked at to see what may be of concern to you. This page will cover general topics, and link to relevant and sourced FAQ pages.



    Aspartame is the most widely used and controversial artifical sweetener currently on the market, and is implicated in a wide-variety of concerns.

    Concern of aspartame appears to be overblown for the most part. Its ability to 'cause headaches' is not well known and highly confounded with placebo/hypochondriacs, as well as being an underresearched topic. FAQ

    Despite being sweet, aspartame does not appear to increase appetite. In actuality, it may actually suppress appetite due to the amino acids that make up the structure of aspartame. FAQ

    Aspartame also does not seem to be a large concern when it comes to spiking insulin in the dosages commonly consumed through diet soda. FAQ Subsequently, fat loss is not impaired with diet soda use and it can be a safe addition to a lifestyle designed to lose body fat. FAQ


    Acidity and Carbonation

    The acidity of diet sodas are one of the legitimate concerns, as diet soda (and to a greater degree, regular soda) are risk factors for dental caries in children. Mentioned in this FAQ


    Caramel Coloring

    Caramel coloring in some cola products (Coke, Pepsi) is due to a molecule called 4-methylimidazole (henceforth 4-MEI), which is produced during browning reactions[1] (not limited to cola). It has also been noted in Soy and Worcestershire sauce[2] as well as coffee[3] and dark beers,[4] although it is most well known for being in caramel soda.[5]

    4-MEI appears to be involved in carcinogenesis, although its role is not clear. Toxicology studies in rats fed high doses of 4-MEI appear to indicate that it has carcinogenic (cancer-promoting) activities,[6] however some argue that it may be anti-carcinogenic when looking at other tumor colonies.[7] It should be noted that this review received funding from the 'American Beverage Association'.

    When looking at the severity of 4-MEI exposure, an oral dosage of greater than 115-120mg/kg bodyweight daily over 106 weeks is associated with metabolic aberrations. Dosages below this do not appear to be much of a concern within this time frame.

    The incidence of mononuclear cell leukemia at an oral dose of 250mg/kg bodyweight was significantly greater than control in females (dose not tested in males) and dosages above 115-120mg/kg bodyweight were associated with increased hepatocellular foci.[6] This high dose was also associated with a 25-fold decrease in mammary tumors as noted by Murray, FJ in a review on the topic.[7] Overall, there were no differences in mortality at any dosage, and body weight was decreased in the highest dosages.[6]

    The mechanism of action may be acting as a co-carcinogen, by inhibiting an enzyme (in P450, CYP2E1) that metabolizes carcinogens.[8]

    The dosage commonly found in soda is 250ppm max in the European Union[9] and is unregulated in the US; common levels found in soft drinks in the US range from 0.3-0.36mcg/mL of beverage,[1][4] which gives a range of 108-130mcg per 12 ounce beverage (375mL). One study estimated an intake of "2.3 and 5.7 mcg/kg body weight/day, in Europe and the United States, respectively"[4] Relatively small dosages when considering the level of 4-MEI that was significant in the rat toxicology study, measured in mg/kg bodyweight.

    Assuming the highest human estimate (5.7mcg/kg daily) and the lowest animal estimate that resulted in difference than control (30mg/kg bodyweight in female rats for alveolar hyperplasia), there is a greater than 5,000-fold difference.

    The most concern you should have from 4-methylimidazole, or 4-MEI, is how it can make your teeth look brown if you don't rinse your mouth.

    1.^Moon JK, Shibamoto TFormation of carcinogenic 4(5)-methylimidazole in Maillard reaction systemsJ Agric Food Chem.(2011 Jan 26)
    6.^Chan PC, Hill GD, Kissling GE, Nyska AToxicity and carcinogenicity studies of 4-methylimidazole in F344/N rats and B6C3F1 miceArch Toxicol.(2008 Jan)
    8.^Hargreaves MB, Jones BC, Smith DA, Gescher AInhibition of p-nitrophenol hydroxylase in rat liver microsomes by small aromatic and heterocyclic moleculesDrug Metab Dispos.(1994 Sep-Oct)