Rafael Urrialde de Andrés
Professor at the Faculty of Biological Sciences of the Complutense University of Madrid and at the Faculty of Pharmacy of the San Pablo-CEU University, and member of the Board of Directors of the Spanish Society of Nutrition
This is an interesting study, although it is limited by the fact that it was carried out in mice. It is essential, not only with sweeteners, but with all other additives and ingredients in food products, to carry out in vivo studies in humans, especially at the gut microbiota level, both in isolation and in combination with other ingredients or foods and beverages, which is how they are actually consumed in the food diet. This is called total diet and longitudinal studies.
In addition, such studies need to rethink the way safety and health assessment is done, to look more deeply into biological as well as toxicological data.
On the other hand, as also indicated in the study, the effects detected were not seen with either acesulfame-k or saccharin. This therefore also reinforces the fact that studies should be on a case-by-case basis and that neither positive nor negative effects can be extrapolated from one additive to another and in this case from one sweetener to another.
Furthermore, one of the possible limiting situations in relation to the threshold of the acceptable daily intake, which also depends on areas or territories - the threshold approved by EFSA is not the same as that approved by the FDA - would be the long-term effects, as it is calculated for a life of 60-70 years and the studies carried out are for a short period of time.
On the other hand, sucralose is one of the most widely used sweeteners in food products, as we found in a study published in 2021 in the journal Frontiers in Nutrition. It is present in: fruit nectars, soft drinks, sports drinks, energy drinks, coffee and tea drinks, breakfast cereals and pastries, yoghurts, fermented milks, milk drinks, cheeses, sauces and condiments, preserved fruit, sweets and chewing gum, desserts and pastries, chocolates, jams, table-top sweeteners, food supplements. According to other studies in which I have participated, such as the review carried out by a team of Spanish scientists and published in the journal Nutrients in 2022, the sweeteners that could have an effect on the gut microbiota are sucralose and saccharin.
Everything indicates that it is increasingly necessary to separate the evaluations and studies of some sweeteners from others, as well as to see and analyse each one separately and not to extrapolate conclusions in a generic way to the whole group of this type of additives, whether they are synthesis or extraction and purification of natural origin. Scientific and technical knowledge is advancing and all this means that the approval and authorisation programmes, as well as the re-evaluation of all additives and of sweeteners in particular, must be coordinated and directed by the Scientific Committees of the European Food Safety Agency in coordination with the Joint FAO/WHO Committee and with other food safety agencies, both in other European countries and, for example, in the United States, Australia, Canada, Japan, Latin American countries, etc. Above all, to clearly differentiate what are observational studies that do not imply causality from in vivo studies with animal models and those that could be carried out in humans.
Doses are possible but probably high and would be difficult to achieve in humans on a continuous daily basis. The problem is also physiological adaptation: let us not forget that it is not the same in mice as in humans. On the other hand, we have to take into account the frequency and time of exposure to consumption, as well as the administration (in this case it was water with sucralose). One of the aspects to be studied in the future will probably be to analyse the behaviour of sucralose in isolation and that produced in different food matrices, because absorption may be different, as well as the possible use of sucralose in this case by the intestinal microbiota. This was the possible effect seen with this sweetener with consequences on other physiological aspects, probably modulated by the gut flora. In the study, for example, it is clear that sucralose in mice does not affect body mass gain, insulin levels or glucose tolerance. In the case of the gut microbiota, as we report in the review published in 2022, in some cases it does and in others it does not, which means that many more studies need to be carried out to determine and assess the scientific evidence.