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Splenda:  Sweet and Bittersweet

Ashley V. Robin

November 11,2008

Any coffee shop aficionado can admit that the little yellow packets of Splenda have become a conspicuous competitor to the other artificial sweeteners.  The health conscious Americans who welcome new diets and health foods have also embraced this product that tastes like sugar but does not contain all those pernicious calories of sugar.  However, given the stigma of other sweeteners, such as saccharin and aspartame, consumers may be chary in accepting another specious substance.  Since 1998 when the FDA approved the main ingredient of Splenda, sucralose, more and more food products have been replacing the sugar ingredient with Splenda.  Meanwhile more restaurants have chosen to stock their tables with Splenda packets neighboring or even prevailing over the other artificial sweeteners.  However, numerous sources remain skeptical about Splenda’s safety.  Likewise, consumers may begin to question whether Splenda is truly as sweet and harmless as the manufacturers claim.



Splenda and its Claims

Splenda is the brand name of the sweetener sucralose manufactured by McNeil Nutritionals.  It is made from sucrose, table sugar, so it is supposed to taste like sugar.  Each packet of Splenda is supposed to taste as sweet as 2 teaspoons of sugar.  The manufacturers advertise Splenda as a “no calorie” sweetener because the body does not metabolize sucralose.  Since the sweetening ingredient, sucralose, contains no calories and no carbohydrates, Splenda can provide a sweet alternative to sugar but without all the calories that are contained in sugar.  Also, since the body does not break down sucralose into energy as it does with sugar or carbohydrates, advertisers claim that the product does not affect glucose levels for diabetics.  This product can be used in coffees or sprinkled atop cereals and fruits.  The manufacturers also advertise its use with baking because it will not change form at high temperatures like other sugar substitutes do.  The Splenda website even offers baking tips and suggestions for using Splenda in place of sugar .


Lastly, this website proclaims the existence of over 100 sound clinical studies conducted over a period of 20 years that confirm the safety of sucralose.  The use of sucralose as a sweetener has already been approved in 80 other countries.  The FDA first approved the use of sucralose as a sweetener in 1998, and since then it has become the nation’s number one choice in low calorie sweeteners.

Composition of Splenda

The sucralose is made from ordinary sugar called sucrose.  Chemical reactions change the molecule’s three hydroxyl (OH) groups into chlorine atoms.  Chlorine and carbon atoms bond to produce a chlorocarbon molecule, also known as sucralose.  The molecule is 600 times sweeter (per gram) than sucrose.  The arrangement of atoms and how the molecules bind to the sweet-receptor proteins in our taste buds cause the excessive sweetness taste (Hoffman, 2007). 

According to a website called the Science of Cooking  Science of Cooking, most chlorocarbons are extremely toxic; however, unlike other chlorocarbons, sucralose does not break down and does not get absorbed by fat.  Most of the sucralose is excreted in feces.  The smaller percentage that is absorbed into the GI tract is released in urine. 


            Other sources do not agree that Splenda simply passes through the body.  One website, called The Truth about Splenda , states its purpose to educate consumers about the true facts about Splenda, and it capitalizes on sucralose’s artificiality and the manufacturer’s false advertising claims.  The website states that the body absorbs 27% of sucralose, which could include the dreaded chlorine atoms.  However, the website does not cite or reference the source of this information.  Furthermore, the Sugar Association sponsors the website and the Truth about Splenda advertising campaign.  The Sugar Association represents sugar beet and sugar cane farmers across America, so, of course, they would want to discourage using Splenda as a replacement for sugar.  Another website advertises Dr. Janet Hull’s book, called Splenda:  Is It Safe or Not?, which claims to provide scientific evidence about the harmful effects of Splenda  For example, this website claims that 15% of the sucralose consumed may be absorbed by the body, contrary to the former website’s claim of 27%.  The website also scares the reader about the possibility of absorbing harmful chlorine.  How much of this information is used to scare the reader into buying the book and how much is used to provide unbiased knowledge to consumers?  Although the websites claim to present consumers with the “truth,” there seems to be some discrepancy in their supposed truthful findings.

Does Splenda Follow its Claims?

No calorie

Although Splenda is advertised as a “no calorie” sweetener, it actually contains a few calories.  The two other ingredients found in Splenda, maltodextrin and dextrose, are carbohydrates and contribute 5 calories per serving.  However, the FDA allows a manufacturer to advertise “no calories” when the amount is negligible (Hoffman, 2007).  Because of Splenda’s lower caloric count, health care professionals may advocate its use in weight loss programs as a sugar substitute.  In a study with Sprague-Dawley rats, when compared to the controls without sucralose intake, the rats with a sucralose diet decreased their food intake and weight (Mann, Yuschak, Amyes, Aughton, & Finn, 2000).  The researchers attributed the weight loss and decreased food intake to the rats finding sucralose diets to be unpleasant.  The findings do not suggest that weight loss will occur for humans.

Substitute for diabetics

Since the body can only absorb small amounts of sucralose, Splenda may help maintain glucose levels in diabetic individuals (Peil & Helling, 2005).  In a study by Mezitis and colleagues (1996), a large does of sucralose did not affect the short term levels of glucose or serum C-peptide.  The researchers measured the participants’ fasting levels of glucose and serum C-peptide levels before administering sucralose.  Then a control group and an experimental group were administered either 1,000 mg sucraolse or a cellulose placebo.  Afterward, the participants ate a 360-kcal liquid breakfast, and then blood samples were collected in subsequent 30-minute intervals up to 240 minutes.  The results showed no significant differences in the glucose and serum C-peptide levels between the control and experimental group.  However, 3 of the 27 participants in the experimental group acquired symptomatic hypoglycemia after sucraolse administration.  The researchers attribute the effect to the individual patients’ low fasting glucose levels and to the common occurrence of hypoglycemia in diabetics.  However, participants with similar fasting glucose levels in the control group did not experience hypoglycemia.  This study also had a very small number of participants, 52 among both groups.  A larger sample would better substantiate the safety of sucralose use.  Also, McNeil Specialty Products, Splenda’s manufacturer, sponsored the grant for this study, and a McNeil employee designed and conducted the study.  Although the study was a double-blind experiment, the researchers may have been partisan.  

Safety and clinical studies

The FDA approved Splenda in 1998 using the available evidence in clinical studies. 

Although the manufacturers, McNeil Nutrionals, proclaimed the existence of over 100 clinical studies confirming their product’s safety, they failed to mention that they conducted or sponsored many of those studies.  None of the researchers of the studies reported significant toxic effects caused by sucralose; however, some did show significant adverse effects or changes among the participants consuming sucralose.  Nonetheless, the researchers all suggest that sucralose was not the cause of such deleterious effects.                                           

To assess the toxicity of sucralose in animals, Mann and colleagues (2000) gave sucralose to rats both in utero (while in their mother’s uterus) and up to 104 weeks after birth.  Rats were assigned to either a control group, consuming a 0% sucralose diet, or to an experimental group, consuming a diet consisting of 0.3%, 1.0%, or 3.0% sucraolse. After 104 weeks, the weight of the rats’ kidneys and brains increased.  Other effects occurred, including statistically significant caecal enlargement (bowel enlargement) and renal changes.  Mann and colleagues state that the large amount of unabsorbed material in the rats’ guts caused such changes.  The researchers suggest that these changes are irrelevant to humans who will only consume sucralose at much smaller doses than those administered to the rats, and, thus, the changes are not “toxicologically significant.”  However, if we are to discount such significant changes merely because smaller animals were used, then there would be no purpose for the use of rats in the study design at all.  The experimental group also exhibited other significant effects, such as cataracts and adrenal cortical haemorrhagic degeneration, but the researchers attributed these effects to the rats’ old age and to the specific characteristics of these particular rats.  However, if these rats had been randomly selected and assigned, then their unique characteristics should not have necessarily yielded significant effects.  Fortunately, there were no statistically significant differences in the occurrence or size of tumors between the control and experimental group.  One must note that in the research article’s conclusion, the researchers emphasized the safety of Splenda considered the other adverse effects as irrelevant. 

In another study, Kille and colleagues (2000) assess the toxic effects of sucralose in the fetal development of rats and rabbits.  The researchers administered sucralose to pregnant rats in dosages of 500, 1000, and 2000 mg/kg/day and to pregnant rabbits in dosages of 175, 350, or 700 mg/kg/day.  The researchers suggested that when compared to controls, sucralose did not cause any effects on normal fetal development in either species.  However, in the adult rabbits, 7 of the 15 pregnant rabbits receiving the 700 mg/kg/day dose experienced mild to severe gastrointestinal damage, including 2 cases resulting in death and 4 cases resulting in abortion.  The researchers attribute these effects to the rabbits’ inability to consume large amounts of unabsorbed substances.  Fortunately, the fetuses of the rabbits showed no significant effects when compared to the controls.  Once again, the researchers in this study exaggerated the results of the fetuses while disregarding, sucralose’s negative impact on the pregnant adult rabbits.

Eventually human participants were studied instead of animals.  Human-Baird, Shephard, Merritt, and Hildrick-Smith (2000) conducted a two-part study using human volunteers.  In both studies various biological measurements were taken, including urinalysis, EKG racings, haematology, and serum biochemistry, prior to the test phase.  In the first study, human volunteers consumed ascending doses of sucralose for 17 days.  The highest dose consumed was 5mg/kg, and neither adverse effects nor significant changes occurred in the biological measurements.  The second study was randomized and controlled; human participants in the experimental group were administered up to 500 mg/day of sucraolse for 13 weeks, and the control group consumed fructose over the 13-week period.  As in the previous study, baseline biological measures were taken, and no significant differences were observed between the two groups at the end of the study.  Although the first study was not randomized nor controlled, the absence of adverse effects and changes in both of the studies provides evidence for the safety of human consumption of high dosages of sucralose.  Unlike the animal studies, the human consumption of sucralose did not produce any unfavorable effects; however, the level of human consumption was also much lower than the level of animal consumption and, thus, probably less harmful.

The human participants in these studies ingested between 5 and 9 times the estimated daily intake (EDI) of sucralose.  The EDI of sucralose is a calculation of the normal human consumption of sucralose, but the figure actually exaggerates a typical human’s consumption.  Although the human participants in the study consumed more than the EDI amount of sucralose, they did not meet the acceptable daily intake (ADI) level of sucralose of 15 mg/kg/day.  This number is considered the maximum amount of sucralose that is safe to consume daily throughout a human’s lifetime.  Although the 13-week study attempted to determine the long-term effects of continuous sucralose usage, the researchers did not administer the ADI dosage, and they defined “long-term” usage too narrowly.  Considering the possibility of lifetime consumption, a longer study may be needed to verify the safety of prolonged consumption of sucralose.

Splenda: Sweet and Bittersweet

In sum, the clinical studies do not explicitly show severe effects involving short-term sucralose usage.  The animals in the study that did experience severe effects consumed an exorbitant amount of sucralose.  For example, the rabbits experienced gastrointestinal problems at 700 mg/kg/day while the human ADI is only 15 mg/kg/day, and the human EDI is about 1.1-2.3 mg/kg/day.  From another perspective, a 160-lb human adult would have to consume 150 soft drinks (12-oz) sweetened by sucralose everyday in order to meet the ADI.  The ADI is an exaggerated amount of normal human consumption of sucralose.  Thus, the results of administering an amount greater than the ADI to rats may be irrelevant to humans.  Thus, both animal and human short-term consumption of sucralose in normal doses, such as the EDI amount, seems harmless given the current clinical evidence.  It also does not provide a significant source of calories, and it may help diabetics stabilize their glucose intake.  Nonetheless, since sucralose is a newly approved substance, no studies have shown the long-term effects of chronic usage (Sham, 2005). 

Since Splenda is now occurring in numerous beverages and foods, more studies need to address the effects of chronic usage.  More individuals with diabetes may decide to use Splenda to obtain a sweet taste in their foods without fluctuating their glucose levels.  More manufacturers may switch to Splenda in their products in order to cater to the diet craze. 



The consistent consumption of sucralose over many years may eventually amount to pernicious effects; however, science has not shown any effects yet.  Splenda has only been tested in short term usage, so we just do not know if it is really as sweet and as harmless as the researchers, or manufacturers, say.  Since sucralose was only approved in 1998, more years must pass before studies can show whether or not effects do occur from chronic sucralose usage.  Furthermore, since the manufacturer of Splenda sponsored most of the clinical studies, we cannot be sure the available evidence is completely unbiased.  On the other hand, we may be swayed by the numerous websites that proclaim the dangerous truths about sucralose, but, in truth, no one can be sure of the facts just yet. 



Baird, I.M., Shephard, N.W., Merritt, R.J., Hildick-Smith, G.  (2000).  Repeated dose study of sucralose tolerance in human subjects. Food and Chemical Toxicology, 38, S123-S129.

Diaz, L.M.  (2000).  Sucralose:  The sugar of the new millennium—FDA’s role:  A hindrance or a help?  New England Law Review, 34, 363-391.

Hoffman, R.  Legally Sweet.  American Scientist, 95, 310-313.

Kille, J.W., Tesh, J.M., McAnulty, Ross, F.W., Willoughby, C.R., Bailey, G.P., Wilby, O.K., Tesh, S.A.  (2000).  Sucralose:  Assessment of teratogenic potential in the rat and the rabbit.  Food and Chemical Toxicology, 38, S43-S52.

Mann, S.W., Yuschak, M.M., Amyes, S.J.G., Aughton, P., & Finn, J.P.  (2000).  A combined chronic toxicity/carcinogenicity study of sucralose in sprague-dawley rats.  Food and Chemical Toxicology, 38, S71-S89.

Mezitis, N.H., Maggio, C.A., Koch, P., Quddoos, A., Allison, D.B., & Pi-Sunyer, F.X.  (1996).  Glycemic effect of a single high oral dose of the novel sweetener sucralose in patients with diabetes.  Diabetes Care, 19, 1004-1005.

Peil, K. & Helling, K.  (2005).  The skinny on Splenda.  Nutrition, 1-2.

Sham, C.W.  (2005).  Splenda-a safe and sweet alternative to sugar.  Nutrition Bytes, 10, 1-5.




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