Widely used food additive shown to alter gut microbiota, adversely affecting health

Summary: These days, a considerable number of food items consumed in the west come from the shelves of supermarkets. Many of these foods are ultra-processed, contain numerous additives, and are ready to eat. In fact, these highly processed foods formed the majority of diet in parts of the western world. Many additives in these foods are proven to be relatively safe. However, most of the supportive data come from studies done in an earlier century. Therefore, there is a need to revisit the safety data regarding these food additives based on the improved knowledge. New studies show that relatively simple additives like carboxymethylcellulose (CMC), which is often added to foods to increase viscosity, may alter gut flora and thus adversely impact health in the long run.

 Most ready-to-food items contain multiple food additives to enhance flavor, color, and preserve foods for longer. Experts approved many of these additives based on studies done several decades back. However, since then, science has evolved considerably. Moreover, early studies failed to consider the long-term impact of these food additives on health.

For example, some food additives are pretty safe when used sparingly and for a few months. However, they may cause severe ill effects on health, on continuous use for years.

One such widely used additive is carboxymethylcellulose (CMC). Since it is a modified form of cellulose, and humans cannot digest cellulose, it appears quite safe. Researchers found that it is not digested, absorbed, or accumulate in the body. And it is readily cleared from the body.

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However, early studies failed to consider its local effects on gut health. Moreover, when experts approved CMC for broader use, they had little understanding of gut microbiota and its role in well-being.

CMC appears quite naïve, and foods mentioning E466 or E469 contain it. However, it is not as naïve as it seems. 

The food industry adds it to various foods to increase their viscosity and use it as a thickener. Many manufacturers add it to foods like ice cream, sauces, and many more1.

However, some recent studies have indicated that it is unsuitable for gut health, especially on prolonged use2. But then many foods in which it is added are frequently consumed food items.

 New studies suggest that it may alter gut microflora and cause gut inflammation, and more

In the mid of the last century, it was common to believe that if the body does not absorb something, it is unlikely to cause any severe health effects. However, now researchers have a different point of view.

It is because researchers have developed a better understanding of the role of gut health in various health conditions, like the role of the gut in brain health, mood, metabolic disorders, and much more. The gut is not just a digestive organ; it produces many hormones, neurotransmitters, vitamins, and other biologically active substances.

It appears that gut microbiota plays a vital role in producing many of the bioactive substances. Thus, anything that alters gut microbiota may increase the risk of a range of diseases.

However, the gut microbiota is a highly complex ecosystem. Therefore, understanding its role in various health conditions is very complicated. To date, science has a limited understanding of how gut microbiota helps maintain good health and prevent disorders.

A new study shows that prolonged consumption of CMC may significantly alter gut microbiota. This increases gut inflammation. This study, published in Gastroenterology, shows that, after all, CMC is not so naïve or safe as believed early3.

This study is significant in the way that it was in human subjects and not animal models. Thus, it provides substantial evidence that CMC is not just harmful to animals, but humans, too.

They divided the subjects into two groups and fed one group with a high dose of CMC. Colonoscopies and analysis of gut mucosa showed significant inflammation in those fed with CMC. In addition, they demonstrated the signs of inflammatory bowel disease and even type 2 diabetes.

What study found that many of these effects would not be visible in the short run. It is because most foods contain only small amounts of it. However, results would be completely different in the long run. Prolonged consumption of CMC would cause irreversible changes in the gut microbiota.

The study did show that CMC can contribute to the increasing prevalence of inflammatory bowel disease and even metabolic disorders. 

However, it should be vital to remember that gut has a much broader role in health. For example, the study did not explore the impact of CMC on the gut-brain axis. Nevertheless, it is quite likely that such food additives might be behind the increasing incidence of mood disorders and even neurodegenerative disorders.

References

1. Yang XH, Zhu WL. Viscosity properties of sodium carboxymethylcellulose solutions. Cellulose. 2007;14(5):409-417. doi:10.1007/s10570-007-9137-9
2. Martino JV, Van Limbergen J, Cahill LE. The Role of Carrageenan and Carboxymethylcellulose in the Development of Intestinal Inflammation. Frontiers in Pediatrics. 2017;5. Accessed February 12, 2022. https://www.frontiersin.org/article/10.3389/fped.2017.00096
3. Chassaing B, Compher C, Bonhomme B, et al. Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome. Gastroenterology. 2021;0(0). doi:10.1053/j.gastro.2021.11.006