Artificial Sweeteners & Gut Bacteria

In an effort to cut back calories and reduce sugar intake, many people have turned to artificial sweeteners, like the ones found in diet sodas or low-calorie cookies, as an alternative to high-sugar foods, but a new study shows artificial sweeteners might not be a healthy choice after all.

The study, which was done in a collaboration between researchers at Nanyang Technology University, Ben-Gurion University, and the Volcani Center, tested the effects of six different sweeteners that have been approved by the FDA on bacteria that are thought to have many of the same properties as the bacteria in the human gut. The study found that even relatively small amounts of artificial sweeteners created a toxic environment for gut-like bacteria.

Which Artificial Sweeteners?

Instead of choosing just one type of artificial sweetener for their study, researchers chose six sweeteners that are either currently very common in low-calorie foods or are expected to become very common in the next few years. The specific sweeteners tested were aspartame, sucralose, saccharin, neotame, advantame, and acesulfame potassium-k.

Aspartame is one of the most common artificial sweeteners on the market and is known by many names including NutraSweet and Equal and is the sweetener that is most often used in diet soda.

Sucralose is also known by the trade name Splenda and is a common additive in low-calorie candy and baked goods.

Saccharin is one of the first artificial sweeteners to be discovered. It is most commonly known by the trade name is Sweet’N Low.

Neotame, which is known by the trade name Newtame, is a relatively new sweetener based on the aspartame formula and is most frequently used in baked goods.

Advantame and acesulfame potassium-k are extremely new artificial sweeteners that have only been approved by the FDA in the last few years and are not yet in common use.

What Did The Study Find?

The study found that if a relatively small dose of artificial sweetener—as little as one milligram per milliliter—were added to the environment of the Escherichia coli (E.coli) bacteria, that the E. coli would begin to show signs of toxicity. The bacteria E. coli was chosen for this study because it mimics many of the characteristics of human gut bacteria and it can be easily modified to give researchers indications of the overall health of the E. coli cell.

Researcher determined the overall health of the cell by using genetically modified bioluminescent E. coli bacteria that glow different colors depending on different types of damage done to the cell. For example, some colors indicated that the sweeteners were damaging the bacteria’s DNA, while other colors indicated damage to the protein structures that help to keep the cell functioning properly.

One particularly interesting result was that each sweetener showed different types of damage to the E. coli, indicating that each type of sweetener might possibly influence human gut bacteria in different ways, and that each sweetener might be drastically more or less harmful to human gut bacteria than the others, although more research would be necessary to determine what types of responses E. coli and human gut bacteria share.

What Does It Really Mean?

While the study is an interesting first step in determining the short and long term effects of many of these sweeteners, it’s important to remember that we should not take the results at face value. The first and most important thing to consider is that these tests were done in a controlled lab environment and not in the gut of any humans or even in the gut of another mammal. This means that while the study is interesting, it is possible, and even quite likely that these results will be different in a human gut than in a test tube.

The other issue that makes extending the results of the study problematic, is that the tests were only done on a single type of bacteria. While it is true that there are many types of E.coli bacteria, as well as other bacteria with similar structures, in the human gut, there are also a host of other bacteria that might react in unexpected ways. Given that the human digestive tract is filled with a wide variety of bacteria, it is very possible that other bacteria may react differently than E. coli to the presence of artificial sweeteners.

Lastly, we have to consider the question of effective dose for humans. The amounts of artificial sweeteners that were tested for the E. coli bacteria in the study are comparatively higher than what one might expect in human food with artificial sweeteners. In addition, most artificial sweeteners are metabolized by the digestive tract before they reach any of the bacteria in the gut, and this means that the amount of artificial sweetener that the gut bacteria would be exposed to would be even lower than what was initially consumed in the original food or drink.

What is The Bottom Line?

The bottom line is that this is early evidence that many of the artificial sweeteners that we use every day might pose a risk to our health, and just because we don’t know that these sweeteners are definitely harmful, doesn’t mean we should take some basic precautions. While it is true that the artificial sweeteners in the study may act differently in the actual digestive tract of a real human and may not cause any harm, it is very unlikely that any of these artificial sweeteners actually produce any benefit to the gut, so it may be safer for most people to stick to foods without these sweeteners.

It is also important to remember that even though these sweeteners have become common in the modern western food market, that they are something completely new to our biology and it is impossible to know exactly how our bodies will react to them in the long-term.