This is the second part of a discussion on synthetic sweeteners. The first part focused on aspartame since that’s the sweetener most commonly found in diet drinks (at least the ones that I drink) and, consequently, the one that gets questioned about the most. In this part, we’ll look at 4 others – sucralose, neotame, stevia (the odd one out – it’s not synthetic), and saccharin.
Just to start things off - I found a neat, and obviously very dated, little youtube video on taste buds that’s relevant.
Sucralose (marketed as “Splenda”) is a derivative of sucrose, substituting three alcohols (O-H) with chlorine atoms. Again, this sweetener was discovered through serendipitous taste-testing – a student was asked to “test” the compound but misinterpreted this request as “taste.”
Sucralose is about 600 times sweeter than sucrose. Sucralose has been eating away at the market share of aspartame, due to its favorable taste, safety, and stability profile (phenylketonurics don’t need to worry about this one). Animal studies on the health effects of sucralose showed that the sweetener is benign, much like aspartame. For an independent review, see: Grotz, V. L. and Munro, I. C. Regulatory Toxicology and Pharmacology 2009 55:1-5. Importantly, sucralose doesn’t accumulate all that much in the body and gets excreted in a timely manner. The small (2-3%) amount that gets accumulated is metabolized much like sucrose such that it’s converted into a form that’s more easily excreted in urine (it’s glucuronidated). This is quite contrary to recent claims made by Dr. Mercola (you may have seen him on The Dr. Oz show), who recently wrote on his website, “Splenda [or sucralose] is actually more similar to DDT than sugar”. I don’t think you need a chemistry degree to see that the chemical structure of sucralose appears to be more similar to that of sucrose and very different from DDT (as shown below). A blogging peer of ours, Nicholas Tesla of Kentucky Chemistry, recently wrote a post that completely debunks Mercola’s statement along with a bunch of other content on Mercola’s ‘sucralose is similar to DDT’ page.
Neotame is structurally very similar to aspartame and is many orders of magnitude sweeter than sucrose. Neotame includes a big greasy hydrocarbon chain added to the aspartic acid nitrogen (presumably to fit better in the receptor, but that’s just my guess – a lot of the details are in the proprietary abyss of patent literature). The neat thing is that this hydrocarbon chain renders this dipeptide immune to the action of the body’s proteases, enzymes which break down proteins. Our bodies’ proteases will break aspartame down to the constituent aspartic acid and phenylalanine, but can’t touch neotame (if anyone else just had “Can’t Touch This” play in their heads, you’re not alone). Since no phenylalanine is released, neotame is considered safer for consumption by phenylketonurics. However, since neotame is a new development in artificial sweeteners, there’s continuing testing for safety.
Then there’s Stevia. Stevia is not a synthetic sweetener, but it is worth mentioning since it is a popular alternative to table sugar (i.e. sucrose). Stevia is a genus of herbs that is known for its sweet leaves. The leaves contain steviol glycosides, natural molecules that contain glucose. These glycosides are potent sweeteners that are roughly 300 times sweeter than sucrose. Stevia has been used for a few decades in Japan to sweeten teas and has been marketed there since 1971. As a result, there is a large amount of data that Stevia is relatively safe for consumption. However, adoption in European and Western countries has been slow, even though the US FDA has determined that it’s safe for consumption even at similarly high doses to aspartame (New York Medical College (15 January 2009). “Notice to the U.S. Food and Drug Administration (FDA) that the use of Rebiana (Rebaudioside A) derived from Stevia rebaudiana, as a Food Ingredient is Generally Recognized as Safe (GRAS)). Many critics of aspartame and the like laud Stevia as the all-natural sweetener, which surely it is, but natural doesn’t necessarily mean safer as our own Dorea Reeser recently discussed in her recent Guest Blog post for the Scientific American, “Natural versus Synthetic Chemicals is a Gray Matter” . The JECFA conducted a similar review on Stevia as they did on aspartame and concluded that Stevia is safe for consumption with one caveat – they suggested that there is a negative effect on hypertension at high doses and, thus, recommended a relatively low recommended daily intake (although still above what one would reasonably consume in a day). Benford, D.J.; DiNovi, M., Schlatter, J. (2006). “Safety Evaluation of Certain Food Additives: Steviol Glycosides” (PDF). WHO Food Additives Series (World Health Organization Joint FAO/WHO Expert Committee on Food Additives (JECFA)) 54: 140.)
The last sweetener I’ll talk about is saccharin. It may seem odd that I’ll leave it to last, considering that it was discovered in 1878. And it is – I have no good reason to put it last. Saccharin, marketed as “Sweet’n’Low,” is a very simple and stable compound derived from coal tar. Because of its stability, saccharin will pass through the body unmetabolized, thus providing no energy to the body. There was some controversy regarding its discovery – you can read more about that on the Wiki article. Saccharin is a really interesting artificial sweetener. It has been around for over a century and still has a significant market share. After some initial safety concerns, the EPA removed saccharin from the list of chemicals hazardous to human beings. Oddly enough, higher animal models such as primates showed increased incidence of cancer in some studies, but the same correlation wasn’t found in humans. The only problem with it is that it gives a slightly bitter aftertaste, which is why things like aspartame were developed. It’s also a compound that strikes me as totally weird – it looks completely different from the other compounds mentioned, but it still triggers the same effect. I’ll look into it in more detail and I’ll write about it if I find something.
That’s it for now. I really want to discuss some of the hits you’ll get when you search “Aspartame safety” and things like that. It’s downright fascinating, what comes up. Fascinating and a little depressing.
Images are from Wikimedia Commons, Dorea, I drew them or they’re pictures of things.