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Publishing in the journal Cancer Research a group of scientists have examined the effects of emulsifiers present in processed foods and report that, in mice, they alter levels of gut bacteria and promote inflammation and colorectal cancer.
Prof. Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:
“This report is a short-term study in mice which were injected with a potent carcinogen called azoxymethane, which is well known to cause gastrointestinal cancers in mice.
“The mice had previously been fed on a standard lab diet but were then made to drink either water supplemented with the food additives polysorbate 80 (E number 433) or sodium carboxymethylcellulose (E number 466) at level of 1%, or unsupplemented drinking water (the control). This is a very high intake of the food additives compared to what might be found in human diets.
“In my opinion, this study has little relevance to human nutrition because the authors induced cancer with a known carcinogen and then exposed the animals to extreme amounts of additives in drinking water. It would be an enormous leap to suggest the findings indicate these food additives might play a role in colorectal cancer in humans.
“Because the mice were injected with a known carcinogen and then fed extreme levels of food additives, we can’t conclude it was the food additives that caused or contributed to the tumours in these mice.
“When these additives are provided in drinking water at such high levels, it is a bit like making the mice drink soapy washing up water. This would be likely to cause disruption to the gut wall and promote inflammation – both factors that would be expected to increase the adverse cancer-causing effects of azoxymethane.
“Mice who did not get the injected carcinogen did not get cancer, only those mice injected with the azoxymethane developed tumours, and more tumours developed in those that had received the additives in the drinking water, probably because the high levels in the water caused irritation and inflammation in the gut. Inflammation increases cell turnover and blood flow to the gut and this would make tumours more likely to develop.
“Polysorbate 80 is used as an emulsifier in some foods such as ice-cream at levels up to 0.1%. The acceptable daily intake (ADI) for polysorbate 80 is 25 mg per kg body weight for humans. As drinking water intake was not recorded in the mouse study, the authors do not report actual intakes of the additive. However, assuming a 20 g mouse consumes 3-5 ml water per day, the intake of additives would be equivalent to 1500-2500 mg per kg which is 60-100 times the human accepted daily intake. So the levels of additives these mice were exposed to is much, much higher than would exist in our diets. Another important limitation is that it was provided in water rather than as part of the food matrix.
“EFSA recently reviewed the safety of polysorbate 80 and concluded that it has very low toxicity1. EFSA noted that the level of no effect in the rodent carcinogenicity study they looked at was 2500 mg per kg of body weight. The accepted daily intake was derived by dividing this number by 100 as a safety factor, so the accepted daily intake for humans is 25 mg per kg of body weight – about a sixtieth of what these mice were exposed to. There is no evidence from human studies to suggest these compounds contribute to human cancer.
“Carboxymethyl cellulose (cellulose gum) is used as thickener as well as to stabilise emulsions2. It has very low toxicity and is also used in artificial tears.
“Overall this short-term mouse study has several limitations, including the extreme levels of additives the mice were fed, and that they had also been injected with a cancer-causing substance. We can’t assume this study is applicable to humans, so it shouldn’t be cause for concern.”
Prof. Sir Colin Berry, Emeritus Professor of Pathology, Queen Mary University London (QMUL), said:
“This mouse study has significant limitations and it tells us little about human colorectal cancer. It should not cause us to worry.
“The underlying genetic mutations involved in human colorectal cancer are already well understood. We know that there are eight or so genetic changes that occur in the epithelium before you finally have a malignant tumour in the colon (this is called the adenoma / carcinoma sequence). In human colorectal cancer there is evidence to say that these genetic changes occur in a particular order and there are data to show how long it all takes. There are genes which predispose to the condition and those born with these genes get the disease early – they start off further along the pathway than those without them. It is also the case that in diseases such as ulcerative colitis, where cell turnover in the colon is faster, the disease occurs early and at a high frequency. So, we already know a lot about how colorectal cancer happens in people.
“The significant limitations of this mouse study include that the quantities of emulsifiers fed to the mice were orders of magnitude greater than the likely dose for any human population. So, the amount of emulsifiers these mice were fed is not equivalent to what we have in our diets. These results do not demonstrate that emulsifiers in food make a contribution to the incidence of colorectal cancer in man.”
‘Dietary emulsifier-induced low-grade inflammation promotes colon carcinogenesis’ by Emilie Viennois et al. published in Cancer Research on Monday 7 November 2016.
Declared interests
Prof. Tom Sanders: “Prof Tom Sanders is a Scientific Governor of the charity British Nutrition Foundation, member of the scientific advisory committee of the Natural Hydration Council (which promotes the drinking of water), and honorary Nutritional Director of the charity HEART UK.
Prof Tom Sanders is now emeritus but when he was doing research at King’s College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks. In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.
Tom also used to work for Ajinomoto on aspartame about 8 years ago.
Tom was a member of the FAO/WHO Joint Expert Committee that recommended that trans fatty acids be removed from the human food chain.
Tom has previously acted as a member of the Global Dairy Platform Scientific Advisory Panel and Tom is a member of the Programme Advisory Committee of the Malaysian Palm Oil Board.
In the past Tom has acted as a consultant to Archer Daniel Midland Company and received honoraria for meetings sponsored by Unilever PLC.
Tom’s research on fats was funded by Public Health England/Food Standards Agency.”
Prof. Sir Colin Berry: “Sir Colin consults for a number of agrochemical and pharmaceutical companies and for the MHRA. He is advises the European Risk Forum.”