Effects of titanium dioxide nanoparticles on nutrient absorption and metabolism in rats: distinguishing the susceptibility of amino acids, metal elements, and glucose

Abstract

Food grade titanium dioxide (TiO₂) containing nanofractions, is commonly applied to whiten and brighten food products, which put consumers under health risks of ingesting TiO₂ nanoparticles (NPs). Although the oral toxicity of TiO₂-NPs has been evaluated in several studies, gaps in knowledge exist regarding interactions between NPs and food components. Therefore, this study aimed to estimate the influence of TiO₂-NPs on nutrient absorption and metabolism through an in situ intestinal loop experiment which conducted on adult Sprague Dawley (SD) rats after 30-d gastrointestinal exposure to TiO₂-NPs of two different sizes (N-TiO₂ and M-TiO₂). Results showed that exposure to TiO₂-NPs caused flat apical membranes with sparse and short microvilli and inflammatory infiltration in small intestine. Both particles were absorbed into small intestinal cells, but N-TiO₂ with smaller size could more easily be transported through gut and raise the blood titanium (Ti) levels. Changes in serum levels of amino acid were also different after exposure to these two particles. After injecting mixed solution of nutrients into in situ intestinal loop, the N-TiO₂ exposure groups displayed significant absorption inhibition of the added histidine (His) and metabolism disorder of some non-added amino acid. However, no influence was observed on metal elements or glucose levels. This study identified TiO₂-NPs with small sizes could affect nutrient absorption and metabolism by inducing intestinal epithelium injury, and amino acids were more susceptible than metal elements and glucose. These findings suggested that foods supplemented with TiO₂-NPs should be carefully consumed by people with high protein requirements, such as children, the elderly, and patients with high metabolic disease or intestinal inflammation.

Keywords:

• Titanium dioxide nanoparticles
• oral toxicity
• nutrient
• absorption
• metabolism

Acknowledgments

The authors gratefully acknowledge the support from Guang Jia and Zhangjian Chen with the experiments.

Author contributions

Yanjun Gao analyzed and interpreted data and wrote the manuscript. Yixuan Ye, Jing Wang, Hao Zhang, Yao Wu, and Yihui Wang conducted the animal experiments, and Yao Wu determined the serum glucose concentrations. Lailai Yan determined the amino acids and elements content. Yongliang Zhang, Shumin Duan, and Lizhi Lvu helped to analyze the data and modify the manuscript. Yun Wang conceived and designed this study. All authors read and approved the final manuscript.

Disclosure statement

Authors listed in the publication do not have any conflict of interest or benefited financially.

Data availability statement

The relevant datasets supporting the conclusions of this article are included within the article, and all datasets used and analyzed during this study are available from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [31971313, 31400863], the Beijing Natural Science Foundation [7172116], and the Young Talent Support Program in Peking University School of Public Health.