Sucralose (E955): safe sweetener or risky sugar alternative?

A refreshing, sweet drink with no calories at all, high-protein pudding or sweets without sugar: sounds tempting, doesn’t it?

Anyone who wants to reduce their sugar consumption and still go on eating sweetened foods has certainly come across sweeteners in processed products at some point. Alongside aspartame, acesulfame or stevia, sucralose is also often used here. In the list of ingredients the artificial sweetener sucralose can also be labelled with the E number E955 and is found, for example, in some sugar-free drinks, yoghurts, sweets or even protein powder.

Sucralose is made from sucrose, which is nothing other than ordinary household sugar. The sugar is chlorinated in the process, which produces what is known as trichlorogalactosucrose, in other words sucralose. This is 600 times as sweet as the substance it is made from. The sweetener is largely not absorbed in our gut and is simply excreted again. That is also why sucralose contains no calories and is often used in diet foods. Sucralose was approved as a safe food additive in the EU in 2004 and has been used in foods ever more widely since then. Within the last few years in particular, the sweetener has been used more and more in foods newly coming onto the market, also in combination with other sweeteners.

But can you consume sucralose without any concerns at all?

The German Federal Institute for Risk Assessment (BfR) gives a maximum acceptable intake for sucralose of 15 mg per kilogram of body weight. This amount can therefore be consumed daily without any health risk having to be feared. For example, a woman with a body weight of 60 kg can consume about 975 mg of sucralose daily for her whole life. There is also a maximum level laid down for drinks, so that a drink sweetened with sucralose may contain at most 300 mg of sucralose per litre.

From the list of ingredients on the food, however, you cannot tell how much sucralose a product actually contains. So if you consume several light products and diet foods over the course of the day, it remains unclear whether this amount is already being reached.

The effects of sweeteners on human beings have been examined more closely for some years now. The latest research findings now show that the sweetener sucralose could have dangerous effects on our health: “The sweetener can damage the DNA material in the cells”, writes the German newspaper WELT. But what is really behind the current headlines?

A team of researchers from the USA (Schiffmann et al. 2023) recently established that an undesirable compound could be formed from sucralose in our gut, one that damages the gut barrier and also our genetic material. The study, published in the Journal of Toxicology and Environmental Health, is worrying not only scientists but also health experts and consumers.

The study’s discoveries are striking: foods containing sucralose are often contaminated. What is meant here is sucralose-6-acetate, a precursor of the sweetener that can hide in tiny amounts in the products. And that is not all: it is suspected that our own microbiome also has a hand in this and lets sucralose-6-acetate be formed from sucralose in the gut. Evidence for this comes, for example, from stool samples of mice, in which around 10% of the amount taken in was excreted as sucralose-6-acetate after the consumption of sucralose. Theory too says that bacteria live in us that would be capable of this conversion.

But what does that mean for us?

What effects would this biochemical change to sucralose have if we are exposed to it to a certain degree?

In cell culture experiments with human intestinal cells it was possible to show that this substance disturbed the barrier function. Because of altered cell connections, the so-called tight junctions, the gut barrier can no longer seal optimally. As a consequence there is a danger that foreign substances and bacteria penetrate more easily and get into our bloodstream. And it was not only the protective layer in the gut that was attacked by this compound: toxicological tests were also able to show that sucralose-6-acetate has a genotoxic effect. Sucralose-6-acetate led here to breaks in DNA strands, the gene material of the cells.

The authors therefore assume that consuming just one drink sweetened with sucralose leads to the threshold value for substances of concern being exceeded.

The findings raise important questions and make us think about the potential risks of sucralose. Is this supposedly harmless sweetener perhaps not as safe as we thought until now?

Let us take a slightly closer look:

The damage to the gut barrier caused by sucralose and by the precursor was demonstrated on cells under isolated laboratory conditions. Whether this effect also occurs in the human body is not confirmed by the study, however. In our gut, for example, a layer of mucus and also the microbiota additionally protect against direct contact with the substance.

That therefore brings us to the most important point of criticism: only sucralose-6-acetate showed a genotoxic effect, not the sweetener sucralose itself.

This effect also only appeared at extraordinarily high concentrations. It is questionable whether such a high amount could actually be taken in through food. These study results also cannot simply be transferred one to one to a real situation in humans.

The authors’ conclusion is based on the assumption that the toxic compound is also formed from sucralose in humans.

So far, however, there is no clear evidence that our body metabolises sucralose in the same way as the small rodents do. Nor is there so far any proven connection between the intake of sucralose and an increased risk of cancer.

In summary it can therefore be said: further investigation is needed into whether sucralose really is converted into relevant amounts of sucralose-6-acetate in humans too and whether long-term health damage could arise from that. It should also be checked whether the traces of sucralose-6-acetate in foods sweetened with sucralose already exceed a toxicologically effective limit.

There are in fact other scientific investigations too that give us indications that sucralose could influence our gut. A clinical study (Suez et al., 2022) showed an altered composition of the microbiome in people with moderate sucralose consumption after only a short period of two weeks. The German Federal Institute for Risk Assessment stresses, however, that the available data are not yet sufficient to establish a clear connection. That is partly because, besides diet, many other factors such as medication, lifestyle or the environment also have an additional effect on the diversity of our gut bacteria.

Researchers have also discovered something else interesting: the regular intake of sucralose could influence our blood sugar level. After study participants with regular sucralose consumption had eaten a test meal, their blood sugar level rose more steeply afterwards than in the control group. These results would indicate that the regular consumption of sucralose as a sweetener could have an undesirable effect on the blood sugar response. And that is not all. Other studies also show that after regular intake sucralose could impair insulin sensitivity and cause the insulin level to rise more steeply after glucose intake.

But if we choose sucralose of all things as a substitute for sugar, because we perhaps have diabetes or want to keep our blood sugar level steady by going without sugar, would that not be counterproductive in that case?

It should be mentioned here that many intervention studies have found no influence on glucose and insulin metabolism either. Because of the contradictory data, the German Federal Institute for Risk Assessment summarises in its report from the beginning of this year that here too the state of research is not yet sufficient for a concrete statement.

As you have read, the data on the sweetener sucralose are partly contradictory. That is why we would like to give you a few tips on how to handle the sweetener.