Ascarid roundworms infect hundreds of millions of people worldwide and numerous domestic and wild animals. The ascarid Toxocara is a common parasite of dogs and cats and can infect humans. However, transmission routes to humans are not completely understood, specifically the role of food in transmission. Ascaris infects humans and pigs worldwide, but it is unclear whether worms infecting pigs and humans represent the same or different species and what contribution zoonotic transmission makes to human infection burdens. To investigate the role of food in Toxocara transmission, we sampled vegetables from allotments and commercial farms in the south of England and used microscopy and molecular approaches to test for Toxocara eggs. Furthermore, we tested tissue exudate from food animals for anti-Toxocara antibodies. To provide insights into genetic structure and zoonotic transmission of Ascaris, we analysed whole genome sequence data from 146 Ascaris worms from pigs and humans in Europe, Asia and Africa. We found evidence of Toxocara on vegetables from allotments (2/82 samples) and commercial farms (30/120 samples). Of the 141 tissue exudate samples, 28% showed evidence of Toxocara antibodies, implicating both vegetables and meat as potential sources of Toxocara transmission. Analysis of Ascaris mitochondrial genomes generated by de novo assembly revealed 4 distinct clades, with some geographical clustering. Nuclear genome analysis indicated separation of Ascaris samples by geography and then by host species. Our results afford insights into multi-host transmission dynamics of widespread zoonotic parasites, providing an important evidence base to inform control and help achieve elimination.