EWG evaluation of food chemicals: Aspartame

While scientific consensus remains limited, some research in animals and humans has suggested associations between aspartame consumption and certain cancers. Oxidative stress, which aspartame can produce, has been proposed to play a role in carcinogenesis. Based on limited evidence, the International Agency for Research on Cancer classifies aspartame as Group 2B (“possibly carcinogenic to humans”).

The World Health Organization (WHO) advised against using non-sugar sweeteners (like aspartame) for weight control. Their review concluded that long-term use does not help with reducing body fat in the long run and is associated with an increased risk of type 2 diabetes and cardiovascular diseases.

Science analysis

What is aspartame and why is it added to food?

Aspartame is a low-calorie sweetener about 200 times sweeter than sugar. It is commonly used as a dietary sugar substitute.

Where is aspartame found in foods?

Aspartame is typically added to diet beverages, powdered drinks and sugar-free chewing gums.

Aspartame is used in 919 of the 172,081 foods added to EWG’s Food Scores between 2023 and 2025.

The 15 food categories with the most products containing aspartame (by supermarket shelf):

Bar chart of product counts by food category; soda 464 and chewing gum 413 highest

^{Source: EWG’s Food Scores. Label created between 2023-01-01 and 2025-10-22.}

What is the regulatory status of aspartame?

As of February 2026, the European Food Safety Authority, or EFSA, was re-evaluating the safety of the mixture aspartame and acesulfame, a sweetener commonly used with aspartame. In the last EFSA evaluation, in 2013, it concluded aspartame was not a safety concern at its acceptable daily intake, or ADI, of 40 mg/kg per body weight per day.

In the U.S., the Food and Drug Administration requires food containing aspartame to state the additive is not for use as a sugar substitute in cooking or baking because it is not heat stable.

The FDA also requires any food containing aspartame to have the label: “Phenylketonurics: Contains Phenylalanine.”

Are foods containing aspartame ultra-processed?

Aspartame and other synthetic sweeteners are common ingredients in ultra-processed foods, or UPF. As an industrially synthesized ingredient and artificial sweetener, it falls into the NOVA framework as a UPF ingredient (Monteiro et al., 2019).

Under a recent California law defining UPF, food served in schools containing aspartame is considered UPF because of aspartame’s property as a non-nutritive sweetener and flavor enhancer (Real Food, Healthy Kids Act, 2025).

Is aspartame allowed in organic foods?

Under Department of Agriculture organic standards, synthetic substances such as aspartame are prohibited in certified organic foods.

What are the potential health harms associated with aspartame?

In 2023, the IARC classified aspartame as possibly carcinogenic to humans based on limited evidence in humans of hepatocellular carcinoma, a type of liver cancer.

A 2026 meta-analysis found that dietary sources of each common non-nutritive sweetener (NNS), including aspartame, and total NNS were associated with higher risk of type 2 diabetes and that total NNS and certain types were associated with some cardiovascular disease outcomes (Wang et al. 2026). Using computer modeling, Yang et al. (2025) showed that aspartame can bind to key proteins in the body, potentially triggering the chronic inflammation and cell damage that could lead to heart disease. Zhang et al (2025) found that aspartame might worsen ischemic stroke by latching onto core targets in the body that control blood flow, clotting, and neuroinflammation. Using animal models, Wu et al (2025) found that aspartame can trigger an insulin spike that causes a specific protein to trap passing immune cells on blood vessel walls, accelerating the arterial plaque buildup that leads to heart disease.

A large population-based cohort study conducted in France found an association between cancer risk, specifically breast and obesity-related cancers, and aspartame and acesulfame-K (Debras et al 2022). Some studies have also observed carcinogenesis in animal models (Landrigan & Straif 2021). But comprehensive safety reviews did not find this link (EFSA Panel on Food Additives and Nutrient Sources 2014; National Toxicology Program, 2005).

A 2025 systematic review of studies of human consumption of aspartame observed an increased incidence of clinical depression, high irritability and spatial orientation impairment at levels below the ADI (Fogel et al 2025). This review also found that those with preexisting neurocognitive deficits or metabolic disorders were more vulnerable to the neurocognitive effects of aspartame (Amin, Hassan & Rashed 2018; Ediga et al., 2023).

Parallel rodent studies monitoring subchronic doses at or below the ADI reported alterations in brain function, such as changes in neurotransmitter activity (Onaolapo et al 2017), as well as decreases in learning and memory deficits (Iyaswamy et al., 2018).

Aspartame breaks down in the body into phenylalanine, aspartic acid and trace amounts of methanol. The re-evaluation of aspartame by the EFSA, in 2013, determined that aspartame can pose risks to people with phenylketonuria (PKU), or high levels of phenylalanine in the blood. Therefore, the ADI does not apply to these individuals.

Phenylalanine can become neurotoxic at elevated concentrations, such as those observed in those with PKU, where it competes with other large neutral amino acids for transport across the blood-brain barrier and may disrupt neurotransmitter precursor availability. Dar et al. (2024) proposed that aspartame-derived phenylalanine could contribute to altered neurotransmitter balance; however, whether this mechanism occurs at typical dietary exposure levels remains uncertain (Dar, 2024).

Aspartic acid, a metabolite of aspartame, can overstimulate nerve cells at high concentrations (Dar, 2024). Excessive stimulation of nerve receptors can contribute to neuronal injury, although the relevance of this mechanism to typical aspartame exposure is uncertain (Zhao & Danbolt, 2014).

This mechanism may also affect microglia, or immune cells within the brain, which can contribute to inflammation. Neuroinflammation is associated with neurodegenerative diseases such as Parkinson’s disease (Bonte et al., 2021).

An acute rodent study observed rats that were given a dose of aspartame 1.5 times higher than the allowable daily intake led to detectable levels of blood methanol for 24 hours and increased lipid peroxidation level in multiple brain regions (Ashok et al., 2015). Methanol breaks down further into other toxic byproducts, such as formate and formaldehyde, a probable carcinogen.

One rodent study found alterations in the structure, growth and function of the placenta of pregnant mice that consumed aspartame (Huang et al., 2023).

Uncertainties/where more research is needed

Because of its flavor profile, aspartame is rarely used in isolation. In commercial products it is frequently paired with other non-nutritive sweeteners like acesulfame-K or sucralose (Basson et al., 2021). More high-quality human research is needed that accurately isolates the long-term health outcomes of independent aspartame exposure from these broader sweetener mixtures (Choudhary & Singh, 2025). Further study on multiple appetite-regulating hormones is also needed (Boxall et al 2025).

Findings in cancer studies remain inconsistent. While some rodent studies show dose-related increases in tumors, epidemiological studies in humans have yet to establish a definitive link (Shaher et al., 2023; Doueihy et al., 2025).

The exact mechanisms by which aspartame causes disease are still largely theoretical (Dar 2024). More empirical evidence in humans is needed to establish a causal link.

Cited resources

Global health and regulatory agencies

EFSA Panel on Food Additives and Nutrient Sources Added to Food (ANS). Scientific Opinion on the Re-Evaluation of Aspartame (E 951) as a Food Additive. EFSA J. 2013, 11, 3496.
National Toxicology Program (NTP). NTP Report on the Toxicology Studies of Aspartame in Genetically Modified Mice; Department of Health and Human Services: Research Triangle Park, N.C., USA, 2005.
World Health Organization. (2023). Summary of findings of the evaluation of aspartame at the international agency for research on cancer (IARC) monographs programme’s 134th meeting, and the joint FAO/WHO Expert committee on food additives (JECFA) 96th meeting. Geneva: World Health Organization.
World Health Organization. (2023). Use of non-sugar sweeteners: WHO guideline. https://www.who.int/publications/i/item/9789240073616

Comprehensive reviews and frameworks

Amin, S.N., Hassan, S.S., & Rashed, L.A. (2017). Effects of chronic aspartame consumption on MPTP-induced Parkinsonism in male and female mice. Archives of Physiology and Biochemistry, 124(4), 292–299. https://doi.org/10.1080/13813455.2017.1396348.
Basson, A.R., Rodriguez-Palacios, A., & Cominelli, F. (2021). Artificial Sweeteners: History and New Concepts on Inflammation. Frontiers in Nutrition, 8, 746247. https://doi.org/10.3389/fnut.2021.746247.
Bonte, M., Idrissi, F. E., Gressier, B., Devos, D., & Belarbi, K. (2021). Protein network exploration prioritizes targets for modulating neuroinflammation in Parkinson’s disease. International Immunopharmacology, 95, 107526. https://doi.org/10.1016/j.intimp.2021.107526.
Boxall, L.R., Eskandari, F., Wallis, J., Bielat, A.D., & Appleton, K. M. (2025). The Effects of aspartame on glucose, insulin, and Appetite-Regulating hormone responses in Humans: Systematic Review and Meta-Analyses. Advances in Nutrition, 16(7), 100449. https://doi.org/10.1016/j.advnut.2025.100449.
Choudhary, A.K., & Singh, N. (2026). Neurotoxic and metabolic effects of chronic aspartame consumption in rodent models: a systematic review and meta-analysis. Toxicology Mechanisms and Methods, 1-14. https://doi.org/10.1080/15376516.2026.2662931.
Dar, W. (2024). Aspartame-induced cognitive dysfunction: Unveiling role of microglia-mediated neuroinflammation and molecular remediation. International Immunopharmacology, 135, 112295. https://doi.org/10.1016/j.intimp.2024.112295.
Doueihy, N.E., Ghaleb, J., Kfoury, K., Khouzami, K.K., Nassif, N., Attieh, P., Ghadieh, H.E., Azar, S., Kanaan, A., & Harb, F. (2025). Aspartame and Human Health: A Mini-Review of Carcinogenic and Systemic Effects. Journal of Xenobiotics, 15(4), 114. https://doi.org/10.3390/jox15040114.
Fogel, M.N., Khalil, A., Khaled, S.F., Rodriguez, E.M., Payne, K.M., Blount, J.R., Petschke, M., Nizamuddin, R.A., Jeidel, F., Riven, V., & Petrosky, S. (2025). Aspartame and its potential neurocognitive effects in humans. Nutrition Reviews, 84(5), 1026-1038. https://doi.org/10.1093/nutrit/nuaf103.
Monteiro, C.A., Cannon, G., Levy, R.B., Moubarac, J., Louzada, M.L., Rauber, F., Khandpur, N., Cediel, G., Neri, D., Martinez-Steele, E., Baraldi, L.G., & Jaime, P.C. (2019). Ultra-processed foods: What they are and how to identify them. Public Health Nutrition, 22(5), 936–941. https://doi.org/10.1017/s1368980018003762.
Nam, T. (2011). Lipid peroxidation and its toxicological implications. Toxicological Research, 27(1), 1-6. https://doi.org/10.5487/tr.2011.27.1.001.
Shaher, S. A.A., Mihailescu, D.F., & Amuzescu, B. (2023). Aspartame Safety as a Food Sweetener and Related Health Hazards. Nutrients, 15(16), 3627. https://doi.org/10.3390/nu15163627.
Wang, M., Wu, O. Y., Wallen, O. G., & Mozaffarian, D. (2026). Artificial and other non-nutritive sweeteners, the microbiome, and cardiometabolic health. Current Atherosclerosis Reports. https://doi.org/10.1007/s11883-026-01429-9
Xiao L., Xian M., Zhang C., Guo Q. and Yi Q. (2024) Lipid peroxidation of immune cells in cancer. Front. Immunol. 14:1322746. doi: 10.3389/fimmu.2023.1322746
Zhou, Y., & Danbolt, N. C. (2014). Glutamate as a neurotransmitter in the healthy brain. Journal of Neural Transmission, 121(8), 799-817. https://doi.org/10.1007/s00702-014-1180-8.

Legislation

21 CFR 172.804 – Aspartame. (n.d.). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-I/section-172.804.
Real Food, Healthy Kids Act, Assemb. Bill 1264, Chapter 467 (Cal. 2025). https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202520260AB1264.

Health impact studies

Ashok I, Sheeladevi R, Wankhar D. Acute effect of aspartame-induced oxidative stress in Wistar albino rat brain. J Biomed Res. 2015 Sep;29(5):390-6. doi: 10.7555/JBR.28.20120118. Epub 2014 Jan 12. PMID: 26445572; PMCID: PMC4585433.
Debras, C., Chazelas, E., Srour, B., Druesne-Pecollo, N., Esseddik, Y., De Edelenyi, F. S., Agaësse, C., De Sa, A., Lutchia, R., Gigandet, S., Huybrechts, I., Julia, C., Kesse-Guyot, E., Allès, B., Andreeva, V. A., Galan, P., Hercberg, S., Deschasaux-Tanguy, M., & Touvier, M. (2022). Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLoS Medicine, 19(3), e1003950. https://doi.org/10.1371/journal.pmed.1003950.
Ediga, M. G., Annapureddy, S., Salikineedy, K., & Nimgampalle, M. (2023). Aspartame consumption causes cognitive impairment in streptozotocin-induced diabetic Wistar rats. Biologia, 78(9), 2393–2407. https://doi.org/10.1007/s11756-023-01363-0.
Huang, S. Y., Sun, R., Chen, Y. C., Kang, L., Wang, C. T., Chiu, C. F., & Wu, H. T. (2023). Aspartame consumption during pregnancy impairs placenta growth in mice through sweet taste receptor-reactive oxygen species-dependent pathway. The Journal of nutritional biochemistry, 113, 109228. https://doi.org/10.1016/j.jnutbio.2022.109228.
Iyaswamy, A., Kammella, A. K., Thavasimuthu, C., Wankupar, W., Dapkupar, W., Shanmugam, S., Rajan, R., & Rathinasamy, S. (2017). Oxidative stress evoked damages leading to attenuated memory and inhibition of NMDAR–CaMKII–ERK/CREB signalling on consumption of aspartame in rat model. Journal of Food and Drug Analysis, 26(2), 903–916. https://doi.org/10.1016/j.jfda.2017.11.001.
Landrigan, P. J., & Straif, K. (2021). Aspartame and cancer – new evidence for causation. Environmental health : a global access science source, 20(1), 42. https://doi.org/10.1186/s12940-021-00725-y.
Onaolapo, A. Y., Onaolapo, O. J., & Nwoha, P. U. (2017). Aspartame and the hippocampus: Revealing a bi-directional, dose/time-dependent behavioural and morphological shift in mice. Neurobiology of Learning and Memory, 139, 76–88. https://doi.org/10.1016/j.nlm.2016.12.021.
Wu, W., Sui, W., Chen, S., et al. (2025). Sweetener aspartame aggravates atherosclerosis through insulin-triggered inflammation. Cell Metabolism, 41(x). https://doi.org/10.1016/j.cmet.2025.01.006
Yang, T., Luo, J. Z., Zhang, L., Li, H., & Wang, J. (2025). Aspartame and cardiovascular disease: Unraveling potential molecular mechanisms through integrative network toxicology, molecular docking, and dynamics simulation. Medicine, 104(47), e46012. https://doi.org/10.1097/md.0000000000046012
Zhang, T., Wang, T., Yu, K., Huang, C., & Bao, K. (2025). Aspartame and ischemic stroke: Unraveling the molecular link through network toxicology and molecular docking analysis. Scientific Reports, 15(1), 23871. https://doi.org/10.1038/s41598-025-08898-z