Figure shows the distribution of unique protein targets of the metabolites among 25 target classes derived from the ChEMBL target hierarchy (orange bars). For comparison purposes, the same distribution is shown for a set of oral drugs with systemic action (blue bars). We can see that the set of drugs has many more interacting targets than the metabolites, reflecting that the former set has been much more tested, as well as the scarce known target space of the later. As a matter of fact, 78.2% of the drug compounds have one or more interacting target, in stark contrast with the 6.4% mentioned before for the metabolites.