Splenda: calorie-free doesn’t equal risk-free

by Caitlin Kennedy, PhD


If you’re a coffee or tea drinker, you probably have tried Splenda, the brand name for sucralose, a sugar-free, no-calorie synthetic sweetener. Sucralose was approved in the US 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. But new research suggests it might not be as safe as everyone thought.

A recent review of research studies – some in rodents and some in humans — suggests 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 and tea. For that reason, 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

The Center for Science in the Public Interest (CSPI), downgraded their safety ratings for Splenda from “safe” to “caution” in June 2013 and called for more research into Splenda’s health effects. See CSPI’s statement on Splenda here.

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 rates as safe, but they admit that more research is needed to be sure.

  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.