Back on March 11, Jon and Mike M. did a short mid-week episode on the science and controversy surrounding Splenda and Stevia, two popular natural sweeteners. Here’s our skeptical take on the claims made for and against both.
Our show notes:
Splenda vs. Stevia: What’s the Deal?
Welcome to the Irreverent Skeptics’ first ever mini-episode! We’re your hosts, Michael McElroy and Jon Ownbey.
Stevia is the common word to refer to the plant stevia rebaudiana which is the sweetest of the stevia species of plants and historically used as a sweetening agent. This sweetness is traced back to glycoside (bound to sugar) compounds of steviol, with the two most important steviol glycosides being stevioside and rebaudioside A.
Unlike other sweetening agents such as aspartame or sucralose, ingestion of stevia in feasible doses confers pharmacological activity. Ingestion of either stevioside or rebaudioside A will result in a circulating level of steviol and its conjugate (steviol glucuronide) which can then exert effects in the body.
In low doses, stevia consumption appears to be associated with general anti-inflammatory and anti-oxidative effects; these effects have been linked to protection of the kidneys, pancreas, liver, and brain when they precede damaging stressors (so although there is some organ protective effects, it is merely due to the general properties of steviol rather than a unique mechanism). Higher doses appear to be linked to fertility problems in animals, and although it is somewhat contested of an issue (some studies in male rats not showing antifertility actions, lack of human studies) it may be prudent to not over consume stevia due to this.
In regards to the genotoxic effects, although overconsumption (or selective choosing of bacterial plates to conduct an Ames test in) is associated with genotoxic effects the potency of this genotoxic effect when it occurs appears to be quite minimal. Cancer causing effects of stevia overconsumption may not be overly relevant due to the low potency of the steviol glycosides and the inherent antioxidant properties also conferring a protective effects (perhaps regulating its own genotoxicity, definitely reduces the reliability) and as such should not be too much of a concern.
And from here:
Splenda is the commercial name and registered trade mark of a sucralose-based artificial sweetener derived from sugar, owned by the British company Tate & Lyle and American company Johnson & Johnson.
The actual caloric content of a single-serving (1-gram packet) of Splenda is 3.36 calories, 31% of the calories of a single-serving (2.8-gram packet) of granulated sugar (10.8 calories). In the United States, it is legally labelled “zero calories”; FDA regulations allow this “if the food contains less than 5 calories per reference amount customarily consumed and per labeled serving”. Splenda contains a relatively small amount of sucralose, little of which is metabolized; virtually all of Splenda’s caloric content derives from the dextrose or highly fluffed maltodextrin “bulking agents” that give Splenda its volume.
A repeated dose study of sucralose in human subjects concluded that “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“. Conversely, a Duke University study conducted on rats (funded by The Sugar Association) shows that sucralose consumption levels of 1.1 mg/kg (below the FDA ‘safe’ level) to 11 mg/kg, throughout a 12-week administration of Splenda, exhibited numerous adverse effects, including reduction in beneficial fecal microflora, increased fecal pH, and enhanced expression levels of certain proteins and enzymes which are known to limit the bioavailability of nutrients and orally administered drugs. These effects have not been observed in humans, and the relevance of this animal study to human health is unknown. The study has been the subject of some controversy, with experts disagreeing over the validity of its conclusions. The other ingredients in Splenda, dextrose and maltodextrin, are listed as generally recognized as safe because of their long history of safe consumption. Other studies have determined that sucralose is not a biologically inert compound, having possible toxic effects, including creation of dioxin-like compounds when sucralose is heated.
Dr. E’s blog – Esther Hersh-Kollars, D.C. (chiropractor)
Seems to be using the “scary chemicals” gambit. Statements like:
The manufacturing process involves the use of many chemicals
(followed by long and scary-sounding chemical names) and
The fact is, the chemical composition of sucralose more closely resembles pesticides than natural sugar.
(Which pesticides? Is the similarity of the composition actually meaningful? After all, sodium explodes in water, and chlorine gas is extremely dangerous. But combine the two in the right way and you get table salt.)
She points out that there hasn’t been much research done on the subject, but then goes on to list a series of self-reported symptoms from people who’ve ingested it:
Individuals have reported symptoms after ingesting sucralose that include skin rashes, shortness of breath, sneezing, swelling, headaches, bloating, nausea, joint pains, anxiety and depression.
This is basically useless in a scientific discussion of the safety. “After ingesting sucralose” is not specific, doesn’t exclude potential confounders, doesn’t indicate dosage, doesn’t indicate the time gap before symptoms occurred, etc. It’s post-hoc, ergo propter hoc in action.
Additionally, she’s either misinformed, using outdated references, or being dishonest when she says:
Although the FDA claims that sucralose is safe at normally consumed dose levels, there are many concerns and unanswered questions about its safety, especially for long-term use. Very few human trials have been done to examine the effects of sucralose; the longest trial lasted only three months. In addition, most of the research was done by the manufacturer.
In fact, per Wikipedia:
“In determining the safety of sucralose, the FDA reviewed data from more than 110 studies in humans and animals. Many of the studies were designed to identify possible toxic effects, including carcinogenic, reproductive, and neurological effects. No such effects were found, and FDA’s approval is based on the finding that sucralose is safe for human consumption.” For example, McNeil Nutritional LLC studies submitted as part of its U.S. FDA Food Additive Petition 7A3987 indicated that “in the 2-year rodent bioassays … there was no evidence of carcinogenic activity for either sucralose or its hydrolysis products …”
(Ref#25 links to an FDA document which discusses several human studies lasting much longer than 3 months, including a 6-month-long study into the use of sucralose in diabetic patients.)
It is prudent to avoid using sucralose until studies are done on the potential for adverse effects after long term use.
I think it’s also prudent to avoid suggesting potential symptoms when the science doesn’t support a connection. Suggestion can be a powerful thing, and if you tell people that “someone who tried this had these symptoms,” they could become hyper-aware of any symptoms at all they experience, and attribute them (rightly or wrongly) to sucralose ingestion.
There’s also a serious naturalistic fallacy going on. After introducing the scary chemical that we don’t know enough about, and recommending that we shouldn’t use it, she says that Stevia is better because it’s natural, and because it’s a traditional herb. However…
It has been enjoyed by millions of people worldwide with no reports of toxic effects in adults or children.
The implication that because nobody has reported toxic effects, there must not be any is a bit dishonest. Research on rats has shown that, quote,
Unlike other sweeteners, stevia has both biologically relevant effects as well as possible toxicity with overdoses (as evidenced by a detectable LD50 in mammals). There appear to be anti-fertility effects, and although these effects in males are not a concern due to occurring at high doses it appears female infertility occurs at lower concentrations.
The infertility seems to be temporary, lasting for about 50-60 days after cessation of ingestion. Similar research hasn’t been done on humans, so it’s a bit hasty to say that a lack of reports of side effects means no side effects – especially in the case of something like infertility, which could easily go unnoticed if it only lasts for a couple months after the last ingestion. (She does mention this… at the end of the next paragraph.)
Moreover, if the claim is that nobody has self-reported toxic effects, she’s going to have to be a bit more explicit about what she means by ‘toxic’. The illustrious 3 Fat Chicks blog (snort) lists a bunch of symptoms they claim people have self-reported.
Obviously, I’m not going to suggest that they’re doing good science either, seeing how they don’t have any references.
Often cited in the argument of Stevia vs. Splenda is that Stevia is “natural” and better for your health since it’s not made with “chemicals” (scary buzz word).
Splenda is processed by the selective chlorination of sucrose, or table sugar, which substitutes three of the hydroxyl groups with chlorine. This chlorination is achieved by selective protection of the primary alcohol groups followed by acetylation (introducing an acetyl functional group) and then deprotection (?) of the primary alcohol groups. Following an induced acetyl migration on one of the hydroxyl groups, the partially acetylated sugar is then chlorinated with an agent and then the acetyl groups are removed to to give sucralose.
The process of Stevia production involves drying the leaves of a stevia rebaudiana plant, then they are boiled. After boiling, the leaves are removed and ethanol or methanol is introduced to the water to obtain the crystallized sweetener.
I’d say that if “chemicals” in the production process are a hangup, neither of these non-nutritive sweeteners is the best choice for you. Both begin with a “natural” product and become an “artificial” sweetener with the introduction of chemicals and processes.
A great example of a stupid article title here: Is Stevia Sweetener Really Natural?