DNA Content and DNA Damage in Raw and Heat-processed Foods

DNA in foods is a source of nucleotides that are salvaged by tissues as building blocks for chromosomal and mitochondrial DNA. A recent study provided preliminary evidence that high-temperature cooking damages the DNA in foods and suggested that certain forms of DNA damage can be taken up as nucleotides via metabolic salvage in cells and animals, directly incorporating genotoxic and mutagenic species into the host DNA. To assess potential risks, we surveyed DNA in 21 food ingredients, including plant- and meat-based foods in raw and roasted form. We find large variation in extractable DNA content, implying widely variable levels of consumption. Cooking resulted in greatly elevated levels of oxidative and deaminated DNA damage in nearly all foods as indicated by 8-oxo-dG and dU nucleotides; with up to 250-fold increases. Studies of human cell lines found that incubation with these damaged nucleosides resulted in cytotoxicity and increased DNA double-strand break levels.