Food additive E171 (titanium dioxide) increases gut problems and cancer risk

Diet has a profound impact on gut microbiota composition and function including the role of food additives.

Food additives are used to improve the texture, preservation and aesthetics of food. Food grade titanium dioxide (TiO2) or E171, is a whitening agent present in over 900 commonly consumed food products. The average adult consumes between 0.7 and 5.9 mg of TiO2 per kg of body weight (BW) per day throughout their life and children are the most exposed, consuming up to 32.4 mg TiO2/kg BW/day in maximally exposed individuals. This is of concern.
The effect of TiO2 on gut is poorly understood yet evidence suggests that TiO2 interacts with gut cells. Studies have demonstrated the accumulation of TiO2 in the mucus layer (which protects the gut cells) in the gut and its uptake by gut cells. A study in rats has shown that TiO2 affects immune cells.
While concern has been raised over the use of titanium dioxide in foods this study investigated the impact of food grade TiO2 on gut microbiota of mice when orally administered via drinking water.

The study found that TiO2 could alter the release of bacterial metabolites in the gut and affect the distribution of the commensal bacteria. They also found reduced expression of the colonic mucin 2 gene, a key component of the intestinal mucus layer, and increased expression of the beta defensin gene, indicating that TiO2 significantly impacts gut homeostasis. These changes were associated with gut inflammation and an increase in the rick of colon cancer.

These findings collectively show that TiO2 is not inert, but rather impairs gut homeostasis which may in turn prime the host for disease development.