February 25, 2015

expert reaction to study on dietary emulsifying agents and inflammation in mice

Researchers publishing in the journal Nature have examined the possibility of emulsifying agents, which are present in a range of food, contributing to adverse health effects. The authors report that in mice, the addition of two emulsifiers to their diet led to changes in the bacterial makeup of the gut as well as inflammation and related metabolic disorders, which they suggest is due to a reduction in the protective mucus barrier which lines the gut.

Ms Catherine Collins, Principal Dietitian at St George’s Hospital NHS Trust, said:

“Emulsifiers are substances that help ‘suspend’ ingredients to create a stable food texture and prevent ingredient separation. An example of this is lecithin found naturally in egg yolk, which when added to oil, lemon juice and vinegar and shaken well, forms a thick food emulsion we know as mayonnaise. Egg lecithin works to keep the oil and water food emulsion in ‘suspension’. Emulsifiers embrace a wide range of types, from natural emulsifiers such as egg and soy lecithins to modified natural or synthetic emulsifiers such as the two tested in this study.

“Emulsifiers are often used alongside or instead of thickeners such as plant gums and seaweed alginates to create and stabilise the texture of some foods – all are given ‘E’ numbers in the E400-499 range. There are several different types of emulsifiers licensed for use in the UK. In this study the researchers evaluated two from a wide range available: polysorbate-80 (E433) and carboxymethylcellulose (E466).

“In mice prone to colitis (an inflamed large bowel condition), feeding pure emulsifier via drinking water and mouse chow led to a change in bowel bacteria types, notably an increase in numbers of ‘mucolytic’ bacteria. Mucolytic bacteria can breakdown the naturally protective layer of mucous that coats our large bowel and normally separate bowel bacteria from direct contact with our intestinal cells. A break in this mucous coating would enable bacteria to come into direct contact with bowel cells, with some able to generate localised and then more distal inflammation and colitis, which is what the researchers found.

“This in interesting research in colitis-sensitive mice but the amount fed to generate the effect (1% of food or water intake) were massive doses far, far beyond the amount we could take in our usual diet. We already know bowel bacteria numbers and types are heavily influenced by changes in our usual dietary habits and not just the traditional consideration of the fibre content in foods. Emulsifiers with ‘E number’ status (including the two evaluated) have passed EU human safety evaluation. However, if you suffer from inflammatory bowel disease that involves the large bowel and want to avoid these particular emulsifiers despite the absence of current research in humans, it’s relatively easy to check your food labels and avoid those with E433 and E466 without affecting the quality of your diet.”

Prof. Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:

“It is already known that high intakes of some carbohydrate polymers when consumed in large amounts can alter gut bacteria, immune responses and cause inflammation for example caregeenan which is derived from seaweed. This paper reports the effects in mice of very high intakes of two carbohydrate-based food additives (carboxymethyl cellulose E466 and polysorbate-80 E433), which are used to thicken/emulsify foods such as ice-cream. Acceptable daily intakes (ADI) are expressed in mg/kg body weight and for E433 it is 10mg/kg body weight. ADI are amounts that can be consumed without any risk to health. The amounts provided in human diets are unlikely to exceed 100-200 mg/d but these investigators fed mice water containing 1% by weight of these compounds. A mouse weighs about 20g and drinks about 5 ml water a day, so an intake of 1% of these additives corresponds to an intake of 50mg/d or 2500 mg/kg. This is comparable to an intake 150,000 mg in a 60 kg adult which is 250 times greater than the ADI. Their conclusion that overeating (hyperphagia) in humans may be driven by food additives is headline grabbing and unwarranted. The fat, sugar and calories provided by ice-cream are far more likely to contribute to weight gain that trivial amounts of these additives.”

‘Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome’ by Chassaing et al. published in Nature on Wednesday 25th February. 

Declared interests

None declared