Is sucralose (a.k.a. Splenda) really as safe an alternative to sugar as its manufacturers and advertisers claim? Or is it really a toxic chemical causing a wide range of health problems including thyroid suppression and weight gain? New research sheds light on this question.
A concerning new study published in the European Journal of Nutrition, entitled “Type of sweet flavour carrier affects thyroid axis activity in male rats”, is the first study of its kind to evaluate the effects of Splenda (Sucralose) on mammalian thyroid function and metabolism. Their findings reveal that sucralose has endocrine disruptive properties on the hypothalamic-pituitary-thyroid axis (HPA axis), resulting in thyroid hormone suppression, increased appetite, and weight gain.
The Many Documented Harms of Sucralose (a.k.a. Splenda)
Before we delve into the details of the new paper, it is important for our readers to understand that this study is not unique in finding harm. There is, in fact, an accumulating body of research on sucralose — a form of sucrose with three added chlorine atoms — showing this chemical marketed as an artificial sweetener is causing a wide range of adverse health effects. For instance, GreenMedInfo’s sucralose research portal reveals 15 different signals of harm linked to this artificial sweetener, such as neurotoxicity. When you add to this well-established body of research the recent discovery that sucralose produces carcinogenic dioxins when heated, the bitter truth about this artificial sweetener — namely, that it is a chemical in the same class as highly toxic pesticides like DDT — comes to light.
This is all the more disturbing when you consider that Splenda is regularly advertised to consumers as a safe sugar alternative specifically for baking applications. For instance, have you seen the TV ads where parents are encouraged to use it presumably to keep their kids healthier than if they used natural sweeteners? If not, you can visit the Splenda Baking and Cooking page which features a picture of a woman holding her son while baking. Also consider that a recent government-funded study found sucralose contaminated 65% of all breast milk samples assayed. In other words, the use of this toxicant is so prevalent that even our most vulnerable populations are incapable of opting out of being exposed to it.
Sucralose has already been demonstrated to promote weight gain and diabetes which undermines its primary marketed ‘benefit.’ Indeed, the new study also found that it promotes weight gain in comparison to an equally sweet, isocaloric diet that only differed in that the sweet sensation was produced by sugar. So, let’s get to the study details now…
Splenda’s Endocrine Disruptive Properties Revealed
The straightforward purpose of the study was described as follows:
Non-nutritive sweeteners are the most widely used food additives worldwide. However, their metabolic outcomes are still a matter of controversy and their effect on the thyroid activity, a key regulator of metabolism, has not been previously studied. Therefore, we aim to determine the influence of the sweet type flavour carrier on selected parameters of thyroid axis activity.
In order to accomplish this, they studied 105 Sprague-Dawley rats, divided into 3 groups, who were fed at their will (ad libitum) for 3 weeks one of the three different diets. The diets had identical caloric content (isocaloric), comprised of starch (wheat starch)differing in the following ways: Diet #1 contained no sugar. Diet #2 contained 10% sucrose (10 grams). Diet #3 contained enough Sucralose (.0167 grams) to create the same sweet flavor intensity as Diet #2 (10% sucrose).
The results obtained indicate that both the presence and the type of sweet taste flavour carrier affect thyroid axis activity both at fasting and postprandial state. Compared to diet with sucrose which stimulates thyroid axis activity, sucralose addition diminishes thyroid hormone synthesis as thyroid peroxidase (TPO) activity, plasma thyroxine (T4), and triiodothyronine (T3) concentration was lower than in SC [sucrose containing] and NS [not sweet] while in non-sweet diet the lowest level of hepatic deiodinase type 1 (DIO1) and the highest reverse T3 (rT3) level indicate on altered thyroid hormone peripheral metabolism.
In other words, sucralose significantly altered the thyroid and metabolic functions of the animals in a manner that could overlap with the symptoms of hypothyroidism.
The researchers concluded:
One principal finding of this study concerns the close relationship between the sweet flavour carrier and the pituitary-thyroid axis activity, which is involved in the meta]bolic adaptation to meal composition. This effect may be observed at various levels. Sucralose intake seems to diminish thyroid axis activity by decreasing TPO activity, TSH, and plasma total TH concentrations, but at the same time, it increases both free T3 and T4 indexes. Those findings confirmed that sucralose is physiologically active and may provoke disturbances in thyroid axis activity.
It is important to understand that this study proves sucralose is not ‘metabolically inert’ as often claimed when questions of its toxicity are raised. Sucralose also increased appetite and weight gain — two things that run diametrically opposed to consumer perception and the irresponsible marketing of its “benefits.”
The study provides more details:
Both food intake and body mass gain were significantly affected by the type of diet (for both p < 0.001). In total, the highest food intake was recorded in the SU [sucralose] group. The average daily intake of sucralose with the diet (14.2 ± 0.4 mg/kg body weight/day) did not exceed the acceptable daily intake (ADI, 15 mg/kg body weight/day).
The food intake recorded during the meal before euthanasia did not differ between NS [not sweet], SC [sucrose], and SU [sucralose], and was 3.98 ± 0.5, 4.22 ± 0.41, and 4.71 ± 0.5, respectively.
The total daily body weight gain in the SU group was significantly higher than in SC and NS, which represented the lowest value (for both p < 0.001). Therefore, the highest diet growth efficiency was also recorded in SU, and there were no differences between NS and SC (Table 2).
Because previous research has established that dietary carbohydrates directly affect thyroid axis activity, the study was designed to keep the carbohydrate content identical in order to isolate only the difference between the artificial and natural sweetener. The results provide compelling evidence that the difference in thyroid and metabolic effects observed between the study groups were due entirely to sucralose’s significant and complex toxicological properties.
Of Mice and Men
The question often emerges following animal studies, as to whether the findings can be extrapolated to humans. The study addresses this point directly as follows:
Despite the known species derived differences in thyroid economy between humans and rodents [65, 66], it was demonstrated that total T4 levels in rodents are a valid indicator of thyroid function in relation to effects in humans . Moreover, humans and rats might be equally sensi-tive to TH synthesis disruptors, and even though in rats the response occurs after a shorter exposure time, the final effect could be the same.
So why are studies like this not regularly performed on humans to remove nagging doubt about their relevance? One reason is the prohibitive cost. Another, perhaps more significant hurdle, is that it is unethical to test chemical safety on human subjects. This obviously makes for great regulatory challenges in unequivocally proving human safety. So, how are the majority of chemicals released onto the market tested for safety? Animals. And so, the argument that animal studies are not sufficient to demonstrate plausible toxicity in humans is absurd, given that the toxicological risk assessments used to justify releasing chemicas like sucralose into the human food supply are invariably based on animal studies. In fact, these animal studies are used to determine an “acceptable level of harm” by extrapolating from them to find the dose that would not cause overt morbidity in a human. The notion, however, that the dose makes the poison, has been completely undermined, given research on petrochemicals, low-dose radiation, nanoparticles, and other non-linear dose responses observed following exposure to extremely low concentrations of toxicants, whose effects are amplifed because they mimic hormones (endocrine disruptors) or cause DNA damage and subsequent cellular transformation into cancer instead of inducing cell death (apoptosis). The most recent classical example of this is the finding that glyphosate, the main in the herbicide Roundup, exhibits estrogenic / carcinogenic / endocrine disruptive properties in the parts-per-trillion range.
Sucralose: A Sweetener or Pesticide?
Another highly concerning observation was that sucralose’s effects are similar to those observed with other organochlorine chemicals in its class, which include dangerous pesticides.
[T]he pattern of HPT axis components—decreased TPO activity, TSH, T4, and T3 plasma concentrations together with increased free-to-total TH ratios in the group on the diet with sucralose—resembles some effects evoked by organochlorine compounds documented in human and animal studies. The inverse relationships between plasma levels of chloroorganic compounds and TSH or the thyroid hormone have been observed [31–35]. The association between high levels of fT4 and the consumption of fish exposed to organochlorinated xenobiotics was found in adults from a certain area in East Slovakia . This could be explained by the binding of chloroorganic compounds residues to transthyretin . In the light of these parallels, our results could raise questions about the physiological inertness of sucralose.
In a previous article, The Bitter Sweet Truth About Splenda, we reported on sucralose’s relationship to organochlorine compounds like DDT, and how both compounds have the potential of accumulating in the body and causing adverse health effects:
The makers of sucralose/Splenda argue that this “remarkably stable” chemical passes unchanged into the urine and feces, when in fact, up to 11% to 27% is absorbed into the body (FDA, 1999). In fact, the varying degrees to which sucralose is absorbed is used as a marker for gut and intestinal permeability to determine certain disease states. Once absorbed, some portion of this chlorocarbon accumulates in the body (between 1.6% to 12.2%). What effects will these accumulated chemicals have? According to James Bowen, M.D:
Any chlorocarbons not directly excreted from the body intact can cause immense damage to the processes of human metabolism and, eventually, our internal organs. The liver is a detoxification organ which deals with ingested poisons. Chlorocarbons damage the hepatocytes, the liver’s metabolic cells, and destroy them. In test animals Splenda produced swollen livers, as do all chlorocarbon poisons, and also calcified the kidneys of test animals in toxicity studies.
The Body Perceives Splenda To Be Toxic
The study also noted that previous researchers have doubted the safety of sucralose based on observations that sucralose intake alters expression of both “rat intestinal P-glycoprotein (P-gp) and cytochrome P-450 isozymes, which are key components of the detoxification system in first-pass drug metabolism .” In other words, sucralose induced responses in the body consistent with the perception that it was doing physical harm, and needed to be removed from the body in the way other toxicants are handled.
Changes also observed consistent with sucralose as a toxicant are: “Alterations in beneficial intestinal microflora and epithelial border function after long-term sucralose ingestion were also recorded [38, 39].”
The researchers conjecture that sucralose’s adverse effects on the thyorid axis would be reflected in “thyroid hisopathology,” i.e. thyroid lesions/tumnors. Could this be one of the causes behind the mysterious global uptick in thyroid cancer diagnoses?
Ditch The Chemicals
This study leaves far more questions than answers. First, why are regulators turning a blind eye to the accumulating body of research indicating that sucralose is a highly toxic chemical whose safety has not be established? Second, why would anyone risk exposing themselves to a chemical when the evidence indicates that artificial sweeteners of all kinds promote weight gain, and increase appetitde — the last two things those who wish to lose weight, or “cut down on sugar” want?
Thankfully we live in an age where research like this is now directly available online, the moment it is published. With greater access to information, we can all better exercise informed consent and take control of our health. We are also to better assess the health benefits of natural substances that render the use of synthetic ones unnecessary, such as honey, stevia, and xylitol. Use the GreenMedInfo.com Research Dashboard to learn more about these alternatives.
About the author:
Sayer Ji is the founder of GreenMedInfo.com, the world’s leading open access, evidence-based resource supporting natural and integrative health modalities. He is Vice Chairman of the Board for the National Health Federation and Fearless Parent, a Steering Committee Member of the Global GMO-Free Coalition (GGFC), and a reviewer at the International Journal of Human Nutrition and Functional Medicine.
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