Researchers at the Harvard School of Public Health (HSPH) have published findings that demonstrate ingested nanocellulose has little acute toxicity when gavaged at low doses. DeLoid et al. examined the safety of purified cellulose fibrils (CNF) and cellulose nanocrystals (CNC) (0.75 and 1.5% w/w)  in vitro in a cell triculture model following digestion using a gastrointestinal tract simulator, as well as suspensions of CNF (1% w/w) in water or cream in a five-week in vivo feeding study. They observed a 10% increase in reactive oxygen species production in 1.5% CNC as compared to controls in the triculture model, but no other effects in cells exposed to 0.75% CNC or up to 1.5% CNF. Notably, in the animal tests, no significant effects were observed, suggesting a no-effect level for acute oral toxicity at >1% CNF. 

These findings complement the work of the on-going Vireo-led Cellulose Nanomaterial Food Safety Study, which is evaluating the safety of daily dietary intake of industrially relevant cellulose nanomaterials in a 90-day feeding study, that will be available later this year. The table below highlights the similarities and differences between the two studies toward understanding of how the data from each can be used complementarily to achieve the goal of demonstrating cellulose nanomaterial safety for food-related applications.