PhytoHub is a freely available electronic database containing detailed information about dietary phytochemicals and their human and animal metabolites. Around 1,200 polyphenols, terpenoids, alkaloids and other plant secondary metabolites present in commonly consumed foods (>350) are included, with >560 of their human or animal metabolites. For every phytochemical, the following is or will be soon available: 1) the chemical structure and identifyers 2) physico-chemical data such as solubility and physiological charge 3) the main dietary sources (extracted from the literature by a team of invited experts and from online databases such as FooDB and Phenol-Explorer) 4) known human metabolites (also manually extracted from the literature and from online databases by the curators), 5) in silico predicted metabolites, generated by Biotransformer (developed by Univ of Alberta) based on machine learning and expert knowledge of host and microbial metabolism, 6) monoisotopic mass and spectral data (collated from libraries of spectra such as MassBank and ReSpect (RIKEN MSn spectral database for phytochemicals), as well as from the literature and from our mass spectrometry/metabolomics laboratory and collaborating groups) 7) hyperlinks to other online databases.