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expert reaction to study looking at association between eating emulsifiers during pregnancy and lactation and health risks in mouse offspring

A study published in PLOS Biology looks at maternal emulsifier consumption and offspring metabolic and neuropsychological health in mice.


Prof Gunter Kuhnle, Professor of Nutrition and Food Science, University of Reading, said:

“The press release is misleading in several ways: emulsifiers are used in many foods, including non-ultra processed foods (lecithin from egg yolk is used in many recipes), and not all ultra-processed foods contain emulsifiers. The study therefore did not investigate the effect of ultra-processed foods on health but only of a specific group of additives – it is not possible to translate this to all ultra-processed foods. Moreover, the data of the study are not strong enough to justify a warning to pregnant and breast-feeding women, especially as this might cause unnecessary concerns. Regulators (including EFSA) have evaluated data on developmental toxicity in studies following the relevant guidelines and did not find adverse effects when using comparable amounts*.

“Further comments: This study investigated the impact of two commonly used emulsifiers, carboxy-methyl-cellulose (CMC, E466) and polysorbate 80 (E433) – two emulsifiers that are used in a range of products. As the authors state, the study found some very small effects and it is impossible to say whether they are of relevance for human consumers. It is important to note that of the many tests the authors have conducted, only few have shown statistically significant differences and as with all studies that measure a lot of parameters, it is possible that these are chance findings. In contrast to human studies, animal studies do not require a pre-registration of study design and endpoints, and so the interpretation of results is more difficult.

“The authors have investigated a combination of both emulsifiers, which makes the interpretation of results difficult as CMC and polysorbate are metabolised very differently: CMC acts similar to dietary fibre and is mainly excreted via faeces while polysorbate is taken up by the body and excreted via urine. They therefore are likely to have very different biological effects. There are a number of differences between the emulsifiers used in this study and those used in foods that make it difficult to translate these results or use them as basis for a risk assessment: a) the authors do not use emulsifiers used in foods but obtained from a supplier of laboratory chemicals, b) the emulsifier is prepared in water and not in food – as it would be consumed normally and c) intake was not controlled and no information on dose per kg body weight is given.

“I cannot comment on the gene expression analysis.

“*The study does not state the amount consumed, but with a water intake of approximately 100 mL per kg body weight, emulsifier intake was 1000 mg/kg BW.”


Dr Duane Mellor, Registered Dietitian and Senior Lecturer, Aston Medical School, Aston University, said:

“This study explores some of the mechanisms why two specific emulsifiers consumed during pregnancy by the female (doe) may result in metabolic and neuropsychological changes in the mouse’s offspring. It is important to acknowledge that although these effects include altered glucose metabolism and the equivalent of anxiety traits in mice, they may not translate to effects in humans. 

“The two emulsifiers tested in this study were methyl-cellulose which is commonly prescribed as a bulking laxative to treat constipation and polysorbate-80 which is a synthetic compound also known as Tween-80 which is used in foods, make-up and medicines. This highlights some of the challenges when using the term emulsifiers, as this describes a wide range of substances, some of which are natural and even may have health benefits and others are synthetic and might alter gut microbiome and impact markers of health as seen in this mouse study.

“Although this study is interesting, it is important to acknowledge that some emulsifiers like lecithin which are found in eggs and soya, contain choline which has been linked to health benefits, and in women who lack a gene (single gene polymorphism (SNIP present in 45% of the population) it can be essential during pregnancy. So, if people are concerned about emulsifiers in food, they should be careful not to exclude choline as this has not been shown to cause any issues, and has potential benefits.

“The authors consider that many ultra-processed foods (UPF) contain emulsifiers, but did not test emulsifiers in UPF, instead they added to the doe mouse’s drinking water. So, this study does not provide any direct link from emulsifiers in UPF and changes in metabolism or neuropsychological health in mice or humans.

“This research highlights that there might be some issues with particular emulsifiers (in this case polysorbate 80 and methyl cellulose) in mice, it does not mean other emulsifiers (especially choline) will have any effect in humans or mice.”


Dr Aaron Bancil, Gastroenterology Specialist Registrar, and Research Fellow, King’s College London, said:

“This is a well-designed study that adds to the body of evidence suggesting that food additive emulsifier consumption could potentially be harmful, in doses equivalent to those consumed by some humans. The study also illustrates how dietary factors around pregnancy and in early infancy are critically important in the moulding of a child’s cognitive development and risk of certain diseases.  The authors of the study identify a potential effect of emulsifier consumption in mice which could cause negative effects in metabolic, neurological and psychological development.

“However, it is not yet possible to state that findings in mice would definitely apply to humans, as there are differences in gut anatomy and other complex factors in humans such as genetics, the gut microbiome, the immune system and the environment, all of which influence development in the womb and during infancy. Additionally, there are over 60 different types of emulsifier in the UK food supply, but this study only looked at two of them. Therefore, it is imperative that each emulsifier is investigated individually as they are likely to have different effects, with some possibly impacting health negatively. What is certain is that we urgently require high-quality studies in humans to validate these results and subsequently direct food guidance and health policy if required.”



Maternal emulsifier consumption programs offspring metabolic and neuropsychological health in mice’ by Maria Milà-Guasch et al. was published in PLOS Biology at 19:00 UK time Thursday 24 August 2023.

DOI: 10.1371/journal.pbio.3002171



Declared interests

Prof Gunter Kuhnle: “I was member of the EFSA ANS panel that evaluated Carboxy-Methyl-Cellulose (E466).”

Dr Duane Mellor: “No competing interests.”

Dr Aaron Bancil has received a research grant from the Helmsley Charitable Trust to investigate the effect of emulsifiers in Crohn’s disease. Dr Bancil has received meeting support fees from Abbvie, Dr Falk, Janssen, Vifor Pharma and speaker fees from Takeda.



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