Fact Check

Is Splenda Inadequately Tested and Unsafe?

Claims that the artificial sweetener Splenda was inadequately tested and is unsafe for human consumption are at odds with numerous scientific studies.

Published Jan 19, 2014

The artificial sweetener Splenda was inadequately tested and is unsafe for human consumption.

Splenda is the trademarked brand name of a sucralose-based artificial sweetener which is several hundred times sweeter than ordinary table sugar (sucrose). According to legend, the discovery of sucralose was (like that of another artificial sweetener, aspartame) something of an accident that occurred by happenstance during the course of unrelated research:

The oddest manner in which a new sweetener came to light was when, one day in 1976, a foreign research student at King's College in London misheard the instructions of his supervisor, Professor L. Hough. Hough was searching for possible synthetic industrial applications of sucrose, the common sugar of cane and beet, and several derivatives had been produced in the laboratory. One of these was a trichlorosucrose (sucrose into which three atoms of chlorine had been introduced). Hough asked Shashikant Phadnis to 'test' the substance, but, his ear being imperfectly attuned to the language, Phadnis instead tasted it. Sucralose, as it became known, is one of the sweetest of all substances and can replace sucrose at less than one-thousandth of the concentration.

After gaining approval by regulatory agencies in the U.S. and Canada (and other countries) in the 1990s, sucralose-based Splenda overtook aspartame-based Equal and NutraSweet and saccharin-based Sweet'N Low as the leading brand in the U.S. artificial sweetener market. The advantages of sucralose over regular sugar are many: it is so sweet that it can be used in much smaller quantities than sugar, it contains no calories, it has no harmful effect on teeth, it can be safely consumed by diabetics, and it is heat-stable and therefore suitable for use in baked goods.

In the years since then, sucralose has (like aspartame before it) become the target of false claims that it is "unnatural" and therefore unsafe:

Before you reach for a packet of Splenda (sucralose), think twice.

Don't be fooled by its slogan "Made from sugar, so it tastes like sugar."

Sucralose was approved for use in foods as a sweetener in 1998. Before approving sucralose, the FDA claimed to have reviewed 110 human and animal studies, but it turns out that only 2 out of those studies were actually on humans.

"It is a chlorinated artificial sweetener in line with aspartame and saccharin, and with detrimental health effects to match," explains Dr. Joseph Mercola.

Let's look as some of the potential health risks associated to Splenda. Reported symptoms: Seizures, Dizziness, Migraines, Allergic reactions, Weight gain and increases in blood sugar, Blurred vision, Gastrointestinal issues.

The reason it is so important to know about the effects of sucralose is because it is the number one selling artificial sweetener in America today. Most of the controversy surrounding Splenda is the way it is advertised. "The sugar industry is currently suing McNeil Nutritionals for implying that Splenda is a natural form of sugar with no calories," Mercola adds.

What is sucralose really?

The truth is that sucralose does start off as sugar, but it is what happens after that is the problem. In the factory, three chlorine molecules are added to the sugar molecule to make sucralose. This alters the chemical structure of the sugar, making it a molecule that does not exist in nature. Because it doesn't exist in nature, the body does not metabolize or digest this molecule. If our bodies were able to metabolize it, then sucralose would no longer have zero calories.

Such rumors, as UC Davis professor Carolyn de la Peña noted in her history of artificial sweeteners, have been fomented in part by the sweetener industry itself despite the established safety of those products:

The modern sweetener industry has thrived by regularly providing consumers with a new option and actively vilifying those that came before it as unnatural and very likely unsafe. The result of this approach, for consumers, is confusion. Obscured are the commonalities between these sweeteners that are, in the end, far more significant than the differences. All are chemicals. None has a closer connection to nature, in either origins or processing, than any other. And all are safe, if used in moderation. Were that not the case, certainly industry-driven scientists would have discovered their competitors' weaknesses and publicized them to consumers well before Internet activists and independent filmmakers.

As is typical in Internet-circulated food health warnings like the example reproduced above (which was largely cribbed from a seventeen-year-old article originally published on the questionable mercola.com web site), all of the information it presents is inaccurate, misleading, and/or outdated. The notion that sucralose has not been subjected to a reasonable and sufficient amount of safety testing is, in particular, woefully inaccurate.

Sucralose has, across the span of many years, been subjected to extensive batteries of short-term and long-term studies in both animals and humans (more than a hundred of which were reviewed during the FDA approval process for sucralose), and none of them has demonstrated any significant risk to humans associated with the consumption of sucralose in normal amounts. A human tolerance study published in the journal Food and Chemical Toxicology in 2000, for example, found "no indication that adverse effects on human health would occur from frequent or long-term exposure to sucralose at the maximum anticipated levels of intake":

Two tolerance studies were conducted in healthy human adult volunteers. The first study was an ascending dose study conducted in eight subjects, in which sucralose was administered at doses of 1, 2.5, 5 and 10mg/kg at 48-hour intervals and followed by daily dosing at 2mg/kg for 3 days and 5mg/kg for 4 days. In the second study, subjects consumed either sucralose (n=77) or fructose (50g/day) (n=31) twice daily in single blind fashion. Sucralose dosage levels were 125mg/day for weeks 1-3, 250mg/day during weeks 4-7, and 500mg/day during weeks 8-12. No adverse experiences or clinically detectable effects were attributable to sucralose in either study. Similarly, haematology, serum biochemistry, urinalysis and EKG tracings were unaffected by sucralose administration. In the 13-week study, serial slit lamp ophthalmologic examination performed in a random subset of the study groups revealed no changes. Fasting and 2-hour post-dosing blood sucralose concentrations obtained daily during week 12 of the study revealed no rising trend for blood sucralose. Sucralose was well tolerated by human volunteers in single doses up to 10mg/kg/day and repeated doses increasing to 5mg/kg/day for 13 weeks. Based on these studies and the extensive animal safety database, there is no indication that adverse effects on human health would occur from frequent or long-term exposure to sucralose at the maximum anticipated levels of intake.

The chapter on sucralose in the textbook Artificial Sweeteners also surveys the extensive body of safety testing that has been performed on sucralose, including those involving long-term exposure and doses far in excess of recommended amounts:

Sucralose is one of the most tested food ingredients available today. It has been found safe for its intended use by health and food safety experts from around the world. Sucralose is permitted for use in more than 100 countries. It is used in thousands of food and beverage products worldwide and is safe for use over an entire lifetime.

More than 100 scientific studies conducted to describe the safety of sucralose represent a methodical, intentional, and broad-range research program, as required by prominent health and food safety authorities. [R]esearch studies conducted in describing the safety of a new food ingredient must be rigorous and comprehensive.

The studies conducted to assess the safety of sucralose investigated possible effects with short-term exposures and long-term, essentially lifetime, exposures, from conception to advanced adulthood. Many of the sucralose research studies utilized very high daily doses of sucralose, doses far greater that what could be expected to be consumed, to understand margins for safe use. Use of such high daily doses was particularly employed in the core sucralose research studies, in accordance with international standards for studies designed to determine potential risk.

The most frequently cited study supposedly documenting the harmful effects of sucralose was one (conducted with rats, not humans, and funded by the Sugar Association) published in the Journal of Toxicology and Environmental Health in 2008 that reportedly found Splenda might "contribute to obesity, destroy 'good' intestinal bacteria and prevent prescription drugs from being absorbed." However, even that study was refuted by one published the following year in Regulatory Toxicology and Pharmacology which reported that an Expert Panel had found that the previous study was "deficient in several critical areas" and that its conclusions "are not consistent with published literature and not supported by the data presented":

A recent study in rats investigated the retail sweetener product, Granulated SPLENDA No Calorie Sweetener (Splenda). The investigators reported that Splenda increased body weight, decreased beneficial intestinal bacteria, and increased the expression of certain cytochrome P450 (CYP450) enzymes and the transporter protein, P-glycoprotein (P-gp), the latter of which was considered evidence that Splenda or sucralose might interfere with the absorption of nutrients and drugs. The investigators indicated that the reported changes were attributable to the sucralose present in the product tested. An Expert Panel conducted a rigorous evaluation of this study. In arriving at its conclusions, the Expert Panel considered the design and conduct of the study, its outcomes and the outcomes reported in other data available publicly. The Expert Panel found that the study was deficient in several critical areas and that its results cannot be interpreted as evidence that either Splenda, or sucralose, produced adverse effects in male rats, including effects on gastrointestinal microflora, body weight, CYP450 and P-gp activity, and nutrient and drug absorption. The study conclusions are not consistent with published literature and not supported by the data presented.

The reference to sucralose's being "a molecule that does not exist in nature," one that "the body does not metabolize or digest" is both inaccurate and relatively meaningless. The fact that the human body does not metabolize sucralose for energy is a positive: it's what makes sucralose non-caloric and therefore ideal as an artificial sweetener. Most sucralose is unabsorbed and therefore passes harmlessly through the body; a relatively small amount (~15%) of consumed sucralose is absorbed but is excreted via urination with no harmful effects:

In the body, sucralose is not able to be digested for energy. Further, sucralose is relatively poorly absorbed from the gastrointestinal tract (GIT). The GIT is replete with enzymes that facilitate rapid uptake of monosaccharides; however, there is no digestion of sucralose at the level of the GIT (or elsewhere in the body). Thus, these enzymes have no impact on sucralose absorption, and specific studies show no active uptake of sucralose. About 85% of consumed sucralose is unabsorbed from the GIT and excreted unchanged in stool. A small amount (approximately 15%) of consumed sucralose is absorbed via passive diffusion across the GIT lumen. Consistent with sucralose being a highly water soluble, small and relatively inert substance, absorbed sucralose is distributed to essentially all tissues and readily excreted in urine. There is no active transport into milk, transplacentally, or across the blood-brain barrier into the central nervous system. Sucralose is not used as a source of energy. It is not dechlorinated, and there is no evidence of degradation to any smaller chlorinated compounds. Sucralose does not bind to proteins in the body, consistent with its relatively non-reactive nature. Most absorbed sucralose, and all unabsorbed sucralose, is excreted unchanged within 24 hours.

As is also typical with Internet-circulated food health warnings, the accompanying laundry list of "reported symptoms" should be taken with many grains of salt. Self-reported adverse events are simply anecdotal raw data; there is no certainty that the reported events were actually due to the product consumed, much less that they demonstrate a causal relationship between the product and the reported events (especially after consumers are influenced by reading anti-sucralose reports that list what symptoms they're "supposed" to be experiencing). Such determinations cannot be made until reports have been investigated, evaluated, and analyzed, and no studies have confirmed that the symptoms listed are a common reaction to sucralose. As Dr. Joe Schwarz observed in his work on food myths and misconceptions:

As with any substance, there can be no absolute guarantee about the safety of sucralose for everyone. Any food or additive, be it peanuts or apples, aspartame or sucralose, can cause a problem for some people. But reactions to sucralose are rare indeed.

There is one thing this piece did get right, although it's both outdated and irrelevant to the issue of the safety of sucralose: the manufacturer of Splenda was indeed sued (nearly fourteen years ago) by a competitor over their slogan "made from sugar, so it tastes like sugar," which falsely implied to consumers that Splenda "in some way actually was sugar, but with the calories stripped out":

In November 2004, Merisant, manufacturer of the table-top, aspartame-based sweetener Equal, sued McNeil Nutritionals, a division of Johnson and Johnson and the manufacturer of Splenda, for false and misleading advertising in Splenda's "made from sugar, so it tastes like sugar" campaign. Merisant invoked the Lanham Act, which prohibits false or misleading advertisements to American consumers, to stop McNeil from making several claims in television and print advertisements that suggested that Splenda was like sugar, only with the calories removed. After three years of fighting in the courts, Johnson and Johnson settled, just before the jury was to return what appeared to be a ruling awarding damages in favor of the plaintiff.

Sucralose, the chemical in the brand-named product Splenda, does, in fact, originate with the sucrose (sugar) molecule. It then undergoes a process of molecule replacement, however, that renders it qualitatively different.

After the lawsuit was settled, Splenda debuted a new slogan: "Just What's Good — it's made from sugar. It tastes like sugar. But it's not sugar."

On 11 March 2016, numerous news outlets reported that an Italian study (published in January 2016) purportedly documented a link between Splenda and cancer in mice. The International Food Information Council (IFIC), a non-profit group aimed at providing science-based evidence with respect to food safety, addressed the publication of the study in an article that criticized the study's methodology and dissonant findings:

As Trevor Butterworth expertly articulated during the last unsupported sucralose scare from these researchers:

The problem hanging over the Splenda finding is that which hangs over the Ramazzini Institute in general: Quality control. No matter what substance the Institute tests for cancer, the results always seem to be positive, whereas other laboratories testing the same substances repeatedly fail to come up with the same findings. [...] All of this has made the Ramazzini Institute something of a joke in European and American science. But, of course, there's nothing to laugh about when you use a charity conference on childhood cancer to promote an international cancer panic.

The FDA and the European Food Safety Authority (EFSA) have both come out on the Ramazzini Institute?s previous work, saying that their conclusions aren't supported by the data. Dr. Magnuson summed it up perfectly: "There are many other problems with this study that we could discuss, such as diet formulation, doses used, lack of dose response, and so on — but the critical point is that it has been well documented that the results from studies by this laboratory are not valid — especially when it comes to lymphoma and leukemia."

IFIC concluded that the "safety and effectiveness of sucralose (and other low-calorie sweeteners in foods) is incredibly well supported," and added that "you shouldn't hesitate to swap them into your diet" in efforts to reduce caloric intake. On 11 March 2016, Splenda issues a statement via their Facebook page referencing the IFIC article and asserting the Italian study's conclusion was an outlier among dozens to the contrary:

Researchers have conducted more than 100 scientific studies on the safety of sucralose over the past 20 years, and they've all declared sucralose safe to enjoy.

Sometimes, however, poorly conducted and unscientific studies make bold headlines and stir up safety fears.

This [IFIC] article sets the record straight[.]


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Brusick, D.   "Expert Panel Report on a Study of Splenda in Male Rats."     Regulatory Toxicology and Pharmacology   2009 Oct;55(1):6-12.

de la Peña.   Empty Pleasures: The Story of Artificial Sweeteners from Saccharin to Splenda.     Greensboro: Univ. of North Carolina Press, 2010.   ISBN 978-0-8078-3409-1   (pp. 219-224).

Gratzer, Walter.   Eurekas and Euphorias: The Oxford Book of Scientific Anecdotes.     Oxford University Press, 2002.   ISBN 978-0-1928-0403-7   (pp. 14-15).

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O'Brien-Nabors, Lyn.   Alternative Sweeteners   [Fourth Edition].     Boca Raton, FL: CRC Press, 2011.   ISBN 978-1-4398-4614-8   (pp. 185-186).

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Schwarz, Joe.   An Apple a Day: The Myths, Misconceptions and Truths About the Foods We Eat.     Toronto: HarperCollins, 2007.   ISBN 978-1-55468-399-4   (pp. 203-204).

Sollid, Kris, R.D..   "Fast Take: Sucralose & Health."     Food Insight   8 February 2016.

David Mikkelson founded the site now known as snopes.com back in 1994.

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