Butyrate and food-grade titanium dioxide in gut cell models
What it found
In lab tests, butyrate changed how gut cells responded to food-grade titanium dioxide in simple cell cultures, but made little difference in more complex models of the gut.
The effects depended heavily on which testing setup was used.
What they found
Animal and lab studies
Cell health in simple cultures
In Caco-2 cells grown alone, titanium dioxide that had been through a simulated stomach and intestine pretreatment reduced metabolic activity to 71% and 68% at the two highest doses. When butyrate was present, this drop was prevented.
Inflammation signal in simple cultures
In the same Caco-2 cells, pretreated titanium dioxide caused a dose-dependent rise in the release of interleukin 8, but only when butyrate was also present. Without butyrate, this rise was not significant.
Barrier and cell health in complex models
In the triple cultures, titanium dioxide with or without butyrate did not change barrier integrity in either the healthy or inflamed model. In the inflamed model, apical LDH release went up with titanium dioxide alone but not when butyrate was also present.
Cytokines in complex models
In the triple cultures, neither titanium dioxide alone nor with butyrate caused significant changes in the release of interleukin 1 beta, interleukin 8 or tumour necrosis factor alpha. In the inflamed model, butyrate increased apical interleukin 8 release compared to the inflamed control, but with a large variation.
Mucins and oxidative stress genes
Titanium dioxide caused only minor changes in mucin gene expression. In the stable triple culture, the highest dose increased MUC2 expression, which was significant without butyrate but not with it. Genes for oxidative stress markers and DNA repair were mostly unchanged, except for a small drop in OGG1 in inflamed cultures at the lower dose.
Radical formation in lab tests
In cell-free lab tests, food-grade titanium dioxide did not generate hydroxyl radicals, either in its pristine state or after pretreatment. Two other particles, fly ash and zinc oxide, did generate them.
What the authors conclude
“Taken together, the effects of fg TiO 2 strongly depend on the applied testing approach.”
Also in their conclusions
- They conclude that butyrate has different effects in simple and complex lab models of the intestine, which could affect the toxicity and pro-inflammatory capacity of pretreated food-grade titanium dioxide.
- They say the cellular impact of butyrate was only relevant in proliferating monocultures of undifferentiated Caco-2 cells and did not show relevance in advanced models.
- They advise that the choice of lab model and exposure scenario is important for hazard testing of food-grade pigments like titanium dioxide, and that further research is needed to understand the nature of the effects seen with combined exposure.
How it was done
Butyrate is a short-chain fatty acid made by gut bacteria and is important for gut health. The authors wanted to see whether butyrate changes the effects of food-grade titanium dioxide on the gut, which had not been studied before.
They grew Caco-2 cells alone and also built a triple culture of Caco-2, HT29-MTX-E12 and THP-1 cells to mimic the healthy and inflamed gut. They exposed these cells to food-grade titanium dioxide, with or without butyrate, for 24 to 48 hours and measured cell health, barrier strength, cytokine release and gene activity.
What it can’t tell you
- These are lab tests using cell cultures, not people or whole animals. They cannot show what happens in a human gut.
- The simple Caco-2 cell model uses cancer-derived cells that behave differently from normal gut cells, so the effects seen there may not reflect real life.
- The complex triple culture model is still a simplified version of the gut and cannot capture the full complexity of digestion, gut bacteria and immune responses in a person.
Who paid
- Conflicts
- The authors declare no competing financial interest.
- Authors work at
- IUF─Leibniz Research Institute for Environmental Medicine, Germany
The paper
- Title
- Effect of Butyrate on Food-Grade Titanium Dioxide Toxicity in Different Intestinal In Vitro Models
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Becht JM, Kohlleppel H, Schins RPF, Kämpfer AAM (2024). Effect of Butyrate on Food-Grade Titanium Dioxide Toxicity in Different Intestinal In Vitro Models. Chemical research in toxicology. doi:10.1021/acs.chemrestox.4c00086Free full textPubMed 39213652DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error