Does Splenda Sweetener Kill Healthy Intestinal Bacteria?

This article was originally published in January 2013.

This post is a brief comment on a study out of Duke University that has lead to the speculation, and also a conviction for some, that the nonnutritive sweetener Splenda destroys healthy gut flora. I’m sure Mercola and others are all over this study. Thanks to Jeff Green for bringing this to my attention via his Facebook post. As well, in this article, I will discuss Joseph Mercola’s little bombshell that Splenda is closer to DDT than sucrose.

What is Splenda Made Of?

Sucralose, the non-nutritive (artificial) sweetener in Splenda, appeared on the market in 1998 but was discovered in 1976. It is six hundred times sweeter than sugar and is heat stable, so it can be used for cooking. A chlorinated form of sugar, it is made from sucrose by substituting three chlorine atoms for hydoxyl groups. The body does not digest it or recognize it as sugar, making it a noncaloric sweetener. Some of it is absorbed, however, making way for all kinds of fearful messages and whole books about the “deception” of it’s makers and the FDA. Most of what it absorbed is passed in the urine, but the fear is that the chlorine may be released and be harmful to the body like other chlorine molecules are. Although it is considered safe for use it is true that not much is known about the long-term consequences of its use.

See also: 7 Artificial (Nonnutritive) Sweeteners Approved for Use In U.S.

Study: Splenda Kills Gut Bacteria?

In the study, Splenda sweetener, which contains 1.1% of actual sucralose and the rest fillers, was administered to rats at 100, 300, 500, 1000mg/kg. That means that at least 100mg of Splenda was given for every kilogram of body weight. Now relate this amount to a human.

Assuming that the same effects would be observed in a human, and that follow-up studies get similar results, how much Splenda is this for a 60kg person or a person that weighs only 140 pounds?

Well, one packet of Splenda is 11 milligrams. To get the minimum 100mg for one kilogram of that body weight, then, you need 9 packets. Then you need to repeat this 60 times, which comes out to be 540 packets of Splenda. Per day. For a diet soda, it’s hard to say, but I’d surmise that this equates to at LEAST 135 12oz cans a day! And that is diet soda with a lot of Splenda in it, equivalent to 4 packets per can. Remember, they gave some of the rats 300 or 1000mg/kg!

See also What Was the First Diet Soda?

We must understand that studies designed to find margins for safe often intentionally use high doses far in excess of what would ever reasonably be consumed. Even the current ADI’s are designed to be highly conservative.

So, this is ridiculous and anybody who consumed that much of anything would have to be a fool. Now, the study points out that the “safe level” is 5mg/kg. These levels are actually called the Acceptable Daily Intake (ADI) and they are set 100 times lower than the levels found to be safe in animal studies. ADI’s are not recommendations as to how much you SHOULD consume of something. They are meant to be the “worst case scenario” and they tend to be much more than you would ever consume, even with the reduction from studies. Even if you disagree with the safe levels as set, it has nothing to do with reasonable consumption of anything and if you get anywhere near those levels, then you really need some dietary counseling!

There is absolutely NO reason to believe, based on this one study, that moderate consumption of Splenda would alter healthy gut flora for a human. As for the results? The study found that “Evidence indicates that a 12-wk administration of Splenda exerted numerous adverse effects, including (1) reduction in beneficial fecal microflora, (2) increased fecal pH, and (3) enhanced expression levels of P-gp, CYP3A4, and CYP2D1, which are known to limit the bioavailability of orally administered drugs.”

Why did Mercola say Sucralose was “Closer to DDT”?

To scare you. That’s why. I’m far, far from being an expert in nutrition and biochemistry. But, as someone with above-average knowledge, I can tell you that this is a completely incompetent statement. See, sucralose was “discovered” out of research looking to make new insecticides. In 1976, UK researchers were experimenting with modifying sugars with chlorine (Cl₂), phosgene (Cl₂CO) and other toxic gases. At some point, one of the younger members was told to ‘test’ a new modified sugar. He misheard and thought he had been told to taste it! So he did, and he found that it was very, very sweet. But it was not toxic. It binds very strongly to the sweet-taste receptors on the tongue. More strongly than ordinary sucrose. That is why we perceive it to be so much sweeter. This new molecule became sucralose and was originally marketed only as Splenda, but now can be found in other brands. This origin in insecticide research is the backbone of the fear-message regarding the sweetener.

Now, if you compare the molecular formula of sucralose to that of DDT, you get something that looks superficially similar, and it is pretty easy for some millionaire supplement selling huxter to convince people that this similarity means that sucralose is just like DDT! So compare them one on top of the other:

Oh, look 14 c’s in DDT and 12 c’s in sucralose. Oh my God, 9 h’s in DDT and 19 h’s in sucralose. Even more! And then those pesky cl’s, they are very much alike. Let’s ignore all the O’s in the sucralose. It’s obviously pretty much the same as DDT.

Well, they say a picture is worth a thousand words. They also say that the molecular formula of a compound, all those letters and numbers, is a bit limited compared to its structural formula, which tells us about how all those things are fitted together with their different chemical bonds. Lest you don’t think how the atoms are arranged is important, well, did you realize that two completely different organic compounds can have the same molecular formula? These are called isomers. Now, I don’t know a bunch about chemistry, but I assure you that most of the people writing scary articles on Splenda know even less than I do. Anyway, this isomer thing means that they can contain the same proportions of various atoms. BUT, those atoms will be arranged differently. With organic compounds, this is very important!

See, the different types of bonds that can exist in a molecule can make all the difference to its chemical properties. It is the structure that really makes the compound do what it does, and doesn’t do, not just the molecular formula. Here is the structural formula of DDT:

Now, remember that sucralose is made from sucrose and three of the hydroxy groups (-OH) are replaced with chlorine atoms (-Cl). So, you’ll see that some of the -OH’s on the sucrose molecule are replaced with -Cl’s. First we have the sucrose structural formula followed by the sucralose forumula:

I do not think you need to be a chemist to get that sucralose is a lot more similar to sucrose than it is to DDT. These are different styles of drawing structural formulas, with the sucrose and sucralose being a 3D representation, but no matter, they are not similar.

Pure DDT is highly hydrophobic, whereas sucralose is highly water-soluble. DDT more easily dissolves, however, in some lipids, while sucralose does not. So, what happens to DDT in the body, and the environment, is much different to what happens to sucralose. DDT cannot be dissolved into the body’s fluids, and so it sticks out like a sore thumb. But because of its lipophilic properties, it can easily bio-accumulate. This was a much bigger problem for birds than it was for us, by the way. Now, sucralose is the opposite. What little bit is absorbed (and it’s just a little) is readily dissolved into the body’s fluid and so diluted, then distributed to most of the body, where it is eventually excreted by the urine. DDT is not dissolved in the fluids, and so cannot be diluted or easily dealt with by the kidneys, and at the same time can be absorbed into the body’s tissues where it accumulates. Not the same. Notice, however, that I said “pure DDT.” Most commercial preparations of DDT are actually a mixture of compounds with a chlorine content that exists in a certain range and additives like iron and aluminum salts and alkalis that serve to make it more sensitive to thermal breakdown (Pure DDT is very stable in heat and doesn’t decompose until it reaches 195°C which is 383 °F).

So what happens to the sucralose that does get absorbed? Some research was done with volunteers who were fed sucralose labelled with ¹⁴C, a radioactive molecule. When the molecules were analyzed in the urine of the volunteers, the researchers found that 92.8% of the sucralose passed through the body unaltered.

Most sucralose is not absorbed by the GI tract and it cannot be actively absorbed. Only about 15% of it is passively absorbed by the GIT lumen. It can not pass into mother’s milk, or transplacentally, nor can it cross the blood-brain barrier. The molecule itself is water soluble and non-reactive. The 2 to 3% that is not excreted in the feces (having not been absorbed), or the urine (having been absorbed) is changed, by common phase II biotransformation, into a highly water-soluble glucuronide conjugate which is not toxicologically significant. All sucralose, once ingested, leaves the body in about 13 hours and there is absolutely no evidence that it accumulates in the body.

That is about as technical as I’d like to get because the fear-mongers like to use “data” such as this to scare you with big words. I’d rather not be accused of doing the same in reverse. Suffice it to say that there is no real reason to fear moderate consumption of sucralose.

I myself do not use Splenda or any other artificial sweeteners on a regular basis. I use sugar in my coffee and iced tea and I drink regular sodas when I want a soda. Same with other sweets. So, I would not be a person to sell Splenda to you. Should you be using scads of the stuff? Probably not. Should you be in general, fearful of it? Probably not. Is there a direct and imminent danger to the public from sucralose? I highly doubt it. ¹Starr, Cecie, Christine A. Evers, and Lisa Starr. Biology: Today and Tomorrow: With Physiology. Australia: Brooks/Cole Cengage Learning, 2010.,²Nollet, Leo M. L. Handbook of Food Analysis, Second Edition, Volume 2: Residues and Other Food Component Analysis. New York, NY [u.a.: Dekker, 2004