(P26-051-25) Quantification of Endotoxin and Inflammatory Potential in Foods

Objectives: Endotoxins are a class of lipopolysaccharides (LPS) produced by gram-negative bacteria that bind the Toll-like receptor 4 (TLR4), which induce an inflammatory response via the nuclear factor kappa B (NF-kB) pathway. Endotoxin has been detected in dairy, meat, and processed foods, but not in fruits and vegetables. There is evidence that grains could be a source of LPS, but its detection and inflammatory potential in foods have not been fully characterized and standardized methods are lacking. The aim of this study was to establish methods for LPS quantification in a range of foods using a high sensitivity assay, the recombinant Factor C assay (rFC), and to characterize the inflammatory potential via TLR4 stimulation in grain-based foods.

Methods: Food samples (n=48; e.g., grains, proteins, fruit & vegetables, fats, processed foods) were examined for LPS using the rFC assay and human embryonic kidney (HEK-293) hTLR4 and NULL2 reporter cell assays. Foods were homogenized, centrifuged, and analyzed with and without filtration through a 0.45 µm PES membrane filter. Statistical analyses included Welch’s ANOVA with Games-Howell post hoc analysis.

Results: All foods had detectable quantities of LPS except for some fats/oils and bottled water which did not have significantly greater LPS than endotoxin-free water (HyClone Laboratories). Foods with lower LPS content were whole wheat bread, mozzarella cheese, and ground beef (400-10,000 EU/serving). Foods with high quantities of LPS ( >137,000 EU/serving) included a frozen pizza, hot dog, and refried beans (p < 0.01). Eighty percent of grains and cereals had LPS >10,000 EU/serving. Serum LPS in grain samples correlated with the TLR4 cell-based assay (r=0.779, p < 0.05).

Conclusions: Endotoxin is detectable in a wide range of foods using the rFC assay and LPS correlated with TLR4 stimulation. Currently, the postprandial rise in LPS after a meal is attributed to translocation of LPS from the intestine, but it is possible this is influenced by LPS in foods.

Funding Sources: Busch Biomedical Rutgers University; USDA NIFA