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Mountain Dew Diet Mountain Dew
Photo: Open Food Facts contributors (CC BY-SA)

Diet sodas

Mountain Dew Diet Mountain Dew

20 fl oz

Poor out of 100 Medium confidence
  • Dye with an EU warning label
  • Contains synthetic dyes
  • Ultra-processed
  • Contains non-nutritive sweeteners
  • Contains caffeine
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Why it scores 25

Mountain Dew Diet Mountain Dew scores 25 out of 100 (Poor) under GoodSwap’s published rules. What moved the score most:

  1. Aspartame: Labels must warn people with phenylketonuria (PKU) because aspartame contains phenylalanine (US and EU). Regulatory
  2. Yellow 5: In the EU and UK, foods with this color must state that it "may have an adverse effect on activity and attention in children". Regulatory
  3. Ultra-processed (NOVA 4): Classified NOVA 4: made with industrial ingredients and additives. Strong

Every line of the math is on The Receipt below, with its evidence tier and sources.

Better sodas

The same kind of product, at least 10 points higher, sold in the US. Never paid placements.

The Receipt

Diet Mountain Dew

START100

Ingredients

  • Aspartame
    Regulatory Labels must warn people with phenylketonuria (PKU) because aspartame contains phenylalanine (US and EU). [1][2][3][4][5][6][7][8][9]
  • Yellow 5
    Regulatory In the EU and UK, foods with this color must state that it "may have an adverse effect on activity and attention in children". [10][11][12][13][14][15]
  • Potassium benzoate
    Strong Benzoates can form small amounts of benzene in drinks that also contain ascorbic acid (vitamin C), especially with heat or light. [16]
  • Acesulfame potassium (Ace-K)
    Strong In the NutriNet-Santé cohort, acesulfame-K intake was associated with higher cancer risk; cause and effect is not established. [7][17][8][9]
subtotal−50

Processing

  • Ultra-processed (NOVA 4)
    Strong Classified NOVA 4: made with industrial ingredients and additives. [18]
  • 5 kinds of ultra-processing markers
    Emerging Industrial additive classes found: color (added), flavoring, non-nutritive sweetener, sequestrant and thickener, stabilizer or gelling agent. [18]
subtotal−24

Nutrition per 100 ml

  • Energy 2 kcal / 100 ml
    Info Energy-dense for its volume. [9]
subtotal−1
TOTAL 25Poor

100 − 75 = 25

Can’t score above 79. Contains aspartame, an ingredient of high concern. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]

GTIN 00012000001345 · 2026-10-05

score v1.3.0 · kb 2026.10.11

Medium confidence

Same product, same score. Every time.

Nutrition per 100 ml

Energy2 kcal
Fat0 g
Saturated fat0 g
Trans fat0 g
Carbohydrates0.1 g
Sugars0.1 g
Added sugars0.1 g
Fiber0 g
Protein0 g
Salt0 g

Serving: 1 bottle (20 fl oz)

Ingredients

High Moderate Not recognized Tap an ingredient for its evidence and rules.
Label text, as published

0% POTASSIUM BENZOATE, CARBONATED WATER, CONCENTRATED ORANGE JUICE, CITRIC ACID, NATURAL FLAVOR. POTASSIUM BENZOATE, CITRUS PECTIN, ASPARTAME, POTASSIUM CITRATE, CAFFEINE, SODIUM CITRATE, ACESULFAME POTASSIUM, SUCRALOSE, GUM ARABIC, SODIUM BENZOATE, CALCIUM DISODIUM, EDTA 1%, YELLOW 5

Allergens and diets

  • Vegan
  • Vegetarian
  • Palm-oil-free

Always check the package: recipes change.

Healthiest diet sodas in the US

More from Mountain Dew

Sources

  1. 21 CFR 172.804 Aspartame

    Electronic Code of Federal Regulations (eCFR), U.S. Office of the Federal Register · Mar 24, 2023 · Law

    “PHENYLKETONURICS: CONTAINS PHENYLALANINE”

    ecfr.gov

  2. Regulation (EU) No 1169/2011, Annex III point 2.3 (aspartame)

    European Union (Official Journal) · Oct 25, 2011 · Law

    “‘contains a source of phenylalanine’ shall appear on the label in cases where aspartame/aspartame-acesulfame salt is designated in the list of ingredients by its specific name.”

    eur-lex.europa.eu

  3. Aspartame hazard and risk assessment results released (IARC, WHO and FAO joint news release)

    World Health Organization · Jul 14, 2023 · Agency assessment

    “Citing “limited evidence” for carcinogenicity in humans, IARC classified aspartame as possibly carcinogenic to humans (IARC Group 2B) and JECFA reaffirmed the acceptable daily intake of 40 mg/kg body weight.”

    who.int

  4. Carcinogenicity of aspartame, methyleugenol, and isoeugenol (IARC Monographs Vol. 134 working group summary)

    The Lancet Oncology · August 2023 · IARC

    doi.org

  5. Aspartame and Other Sweeteners in Food

    U.S. Food and Drug Administration · Feb 27, 2025 · Regulator

    “The FDA disagrees with IARC’s conclusion that these studies support classifying aspartame as a possible carcinogen to humans.”

    fda.gov

  6. EFSA completes full risk assessment on aspartame and concludes it is safe at current levels of exposure

    European Food Safety Authority · Dec 10, 2013 · Agency assessment

    “Aspartame and its breakdown products are safe for human consumption at current levels of exposure”

    efsa.europa.eu

  7. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study

    PLOS Medicine · Mar 24, 2022 · Peer-reviewed

    “In this large cohort study, artificial sweeteners (especially aspartame and acesulfame-K), which are used in many food and beverage brands worldwide, were associated with increased cancer risk.”

    doi.org

  8. WHO advises not to use non-sugar sweeteners for weight control in newly released guideline

    World Health Organization · May 15, 2023 · Agency assessment

    “The recommendation is based on the findings of a systematic review of the available evidence which suggests that use of NSS does not confer any long-term benefit in reducing body fat in adults or children.”

    who.int

  9. Dietary Guidelines for Americans, 2025–2030

    U.S. Department of Health and Human Services and U.S. Department of Agriculture · January 2026 · Regulator

    “Limit foods and beverages that include artificial flavors, petroleum-based dyes, artificial preservatives, and low-calorie non-nutritive sweeteners.”

    cdn.realfood.gov

  10. Regulation (EC) No 1333/2008 of 16 December 2008 on food additives

    European Union (Official Journal) · Dec 16, 2008 · Law

    “may have an adverse effect on activity and attention in children.”

    eur-lex.europa.eu

  11. Regulation (EC) No 1333/2008 (as it applies in the UK), Annex V: food colours requiring additional labelling

    legislation.gov.uk (The National Archives) · Law

    “may have an adverse effect on activity and attention in children.”

    legislation.gov.uk

  12. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial

    The Lancet · November 2007 · Peer-reviewed

    “Artificial colours or a sodium benzoate preservative (or both) in the diet result in increased hyperactivity in 3-year-old and 8/9-year-old children in the general population.”

    doi.org

  13. Tracking Food Industry Pledges to Remove Petroleum Based Food Dyes

    U.S. Food and Drug Administration · Regulator

    “FD&C Green No. 3, FD&C Red No. 40, FD&C Yellow No. 5, FD&C Yellow No. 6, FD&C Blue No. 1, and FD&C Blue No. 2—by the end of 2027.”

    fda.gov

  14. California AB 2316 (2024), Pupil nutrition: substances: prohibition

    California Legislative Information · Sep 28, 2024 · Law

    “beginning December 31, 2027, would prohibit a school district, county superintendent of schools, or charter school”

    leginfo.legislature.ca.gov

  15. 21 CFR 74.705 FD&C Yellow No. 5

    Electronic Code of Federal Regulations (eCFR), U.S. Office of the Federal Register · Dec 29, 2016 · Law

    “shall specifically declare the presence of FD&C Yellow No. 5 by listing the color additive as FD&C Yellow No. 5 among the list of ingredients.”

    ecfr.gov

  16. Benzene production from decarboxylation of benzoic acid in the presence of ascorbic acid and a transition-metal catalyst

    Journal of Agricultural and Food Chemistry · May 1993 · Peer-reviewed

    doi.org

  17. Re-evaluation of acesulfame K (E 950) as food additive (plain language summary)

    European Food Safety Authority · Apr 30, 2025 · Agency assessment

    “The acceptable daily intake (ADI) considered safe for all population groups was set at 15 mg/kg body weight (bw) per day.”

    efsa.europa.eu

  18. Ultra-processed foods: what they are and how to identify them

    Public Health Nutrition · April 2019 · Peer-reviewed

    doi.org

  19. HHS, FDA to Phase Out Petroleum-Based Synthetic Dyes in Nation’s Food Supply (press release)

    U.S. Food and Drug Administration · Apr 22, 2025 · Regulator

    “Initiating the process to revoke authorization for two synthetic food colorings—Citrus Red No. 2 and Orange B—within the coming months.”

    fda.gov

  20. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses

    BMJ · Feb 28, 2024 · Peer-reviewed

    “Greater exposure to ultra-processed food was associated with a higher risk of adverse health outcomes, especially cardiometabolic, common mental disorder, and mortality outcomes.”

    doi.org

  21. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake

    Cell Metabolism · July 2019 · Peer-reviewed

    doi.org

  22. Spilling the Beans: How Much Caffeine is Too Much?

    U.S. Food and Drug Administration · Regulator

    “For most adults, the FDA has cited 400 milligrams* a day — that's about two to three 12-fluid-ounce cups of coffee — as an amount not generally associated with negative effects.”

    fda.gov

  23. Regulation (EU) No 1169/2011, Annex III point 4.1 (beverages with high caffeine content)

    European Union (Official Journal) · Oct 25, 2011 · Law

    “‘High caffeine content. Not recommended for children or pregnant or breast-feeding women’”

    eur-lex.europa.eu