Risks of Splenda: Too Risky to Use?

Caitlin Kennedy, PhD and Diana Zuckerman, PhD, National Center for Health Research

If you’re a coffee or tea drinker, you probably Splendahave tried Splenda, the brand name for sucralose, a sugar-free, no-calorie synthetic sweetener. Sucralose was approved in the U.S. by the FDA in 1998.[1] It’s in the yellow packets and is one of the most popular no-calorie sweeteners in the US.  Splenda is also in Diet Pepsi and some other soft drinks. Since 2014, evidence has grown that Splenda might not be so safe, and in 2016, that evidence has many experts worried.

The Center for Science in the Public Interest (CSPI), downgraded their safety ratings for Splenda from “safe” to “caution” in June 2013 and from “caution” to “avoid” in February 2016.

The concerns emerged because of a study of mice published in the International Journal of Occupational and Environmental Health in January 2016.  The study is better designed than the industry-funded studies, all of which concluded that Splenda was safe.  In contrast, the 2016 article is based on a larger study of mice who were exposed in utero rather than in adolescence.

A previous review of research studies – some in rodents and some in humans — suggested that sucralose may have several different health risks.[2] In adolescents and young adults, it affects the hormones that influence glucose levels in those who are healthy and in Type I diabetics.[3] Rats that consumed sucralose had less than half the normal amount of gut bacteria, which can influence health, and unfortunately, it harmed the “good” gut bacteria more than the “bad.”[4] Three months after the rats had stopped consuming sucralose, the rats’ gut bacteria were still not back to normal.

Sucralose may also interfere with medications. Rats who consumed it had higher levels of enzymes that affect metabolism,[4] which could make medications less effective because they are more difficult to absorb.[5]

Sucralose may even cause cancer. Mice who consumed sucralose are more likely to develop lymphoma, a type of blood cancer.[1]

Splenda is widely marketed as a replacement for sugar in baking, in addition to coffee, tea, and some soft drinks. Since it is used for baking, it is especially worrisome that Splenda is now known to chemically break down when heated to temperatures commonly used in baking.[6] [7] When sucralose is baked with glycerol, a type of sugar that is commonly used in baked goods, it can create chloropropanols, chemical contaminants that can cause cancer.[8]

A 2020 study published in the journal Cell Metabolism by a group of Yale researchers found that consuming the common artificial sweetener sucralose (found in Splenda, Zerocal, Sukrana, SucraPlus) in combination with carbohydrates can turn a healthy person into one with high blood sugar.[9] Similarly, a 2020 French study of more than 100,000 adults followed for 10 years found that people who drank a median of just over 6 ounces of artificially sweetened beverages per day were at higher risk for developing cardiovascular disease than people who did not consume these drinks, but consuming a median of 1.4 ounces or less did not.[10] The study also found that consuming similar amounts of sugar-sweetened beverages (beverages containing more than 5% sugar) was also associated with heart disease. Scientists hypothesize that artificial sugars trigger inflammation and alter metabolism, the gut microbiome, and blood vessels that lead to unhealthy cholesterol levels, high blood pressure, and type 2 diabetes. While these findings have yet to be replicated in other studies and countries, they raise important questions about the use of artificial sweeteners and their effects on weight as well as overall health.

In May of 2023, the World Health Organization (WHO) warned that artificial sweeteners, when consumed long term, do not reduce body fat in either adults or children and could increase the risk of Type 2 diabetes, cardiovascular diseases, and mortality in adults. This warning is based on the findings of a systematic review of all available evidence and contradicts earlier studies that have said these sweeteners are not good nor bad. The recommendation applies to everyone except those with pre-existing diabetes and includes all synthetic and natural non-nutritive sweeteners such as aspartame, saccharin, sucralose, and stevia. The WHO recommendation is conditional, so policy decisions will be made after discussion based on specific country contexts.

If you don’t like the risks of no-calorie sweeteners, what can you do? A teaspoon of sugar is only 17 calories, so using one or two teaspoons of sugar in tea and coffee is less than one quarter of the calories of most non-diet soft drinks. We also suggest drinking more water or unsweetened beverages — for example, water with a slice of lemon, orange, or other fruit is a delicious and healthy option.

Rebiana (brand name: Stevia) is the only no-calorie sweetener that CSPI doesn’t recommend avoiding, but they also say that more research is needed to be sure.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

  1. U.S. Food and Drug Administration. 1998. Food additives permitted for direct addition to food for human consumption; sucralose. 21CFR Part 172 (Docket No. 87F-0086). Fed. Reg. 63(64): 16417–16433. http://www.gpo.gov/fdsys/pkg/FR-1998-04-03/pdf/98-8750.pdf (accessed December 5, 2013).
  2. Schiffman SS, Rother KI. Sucrolose, a synthetic organocholorine sweetener: Overview of biological issues.Journal of Toxicology and Environmental Health, Part B 2013;16;399-451. doi: 10.1080/10937404.2013.842523
  3. Brown RJ, Walter M, and Rother KI. Effects of diet soda on gut hormones in youths with diabetes. Diabetes Care 2012; 35;959–964.
  4. Abou-Donia MB, El-Masry EM, Abdel- Rahman AA, McLendon RE, and Schiffman SS. Splenda alters gut microflora and increases intestinal Pglycoprotein and cytochrome P-450 in male rats. J. Toxicol. Environ. Health A 2008; 71;1415–1429.
  5. Dürr D, Stieger B, Kullak-Ublick GA, Rentsch KM, Steinert HC, Meier PJ, and Fattinger K. St John’s Wort induces intestinal P-glycoprotein/MDR1 and intestinal and hepatic CYP3A4. Clin. Pharmacol. Ther. 2000; 68;598–604.
  6. Hutchinson SA, Ho GS, and Ho CT. Stability and degradation of the high-intensity sweeteners: Aspartame, alitame, and sucralose. Food Rev. Int. 1999; 15;249–261.
  7.  Bannach G, Almeida RR, Lacerda LG, Schnitzler E, and Ionashiro M. Thermal stability and thermal decomposition of sucralose. Ecl. Quím. São Paulo 2009; 34;21–26.
  8. Rahn A, and Yaylayan VA. Thermal degradation of sucralose and its potential in generating chloropropanols in the presence of glycerol. Food Chem. 2010; 118;56–61.
  9. Dalenberg JR, Patel BP, Denis R, Vinke PC, Luquet S, Small DM. Short-Term Consumption of Sucralose with, but Not without, Carbohydrate Impairs Neural and Metabolic Sensitivity to Sugar in Humans. Cell Metabolism. Clinical and Translational Report, Volume 31, Issue 3, P493-502E7. March 03, 2020. https://www.cell.com/cell-metabolism/fulltext/S1550-41312030057-7
  10. Chazelas E, Debras C, Srour B, et al. Sugary drinks, artificially sweetened beverages, and cardiovascular disease in the Nutrinet-Santé cohort. Journal of the American College of Cardiology. 2020; 76(18):2175-2177. https://www.jacc.org/doi/full/10.1016/j.jacc.2020.08.075
  11. World Health Organization. (n.d.). Who advises not to use non-sugar sweeteners for weight control in newly released guideline. World Health Organization. https://www.who.int/news/item/15-05-2023-who-advises-not-to-use-non-sugar-sweeteners-for-weight-control-in-newly-released-guideline