Archaeologists have used isotope analysis (δ13C, δ15N) of the collagen of human bones, as well as knowledge of available nutrients, to infer that the diet of the ancient Maya was drawn from the resources of the Maya forest landscape. The interpretations have focused on plant carbohydrates from maize and protein dominated by white-tail deer. The δ15N values of bone collagen suggest that most of the protein requirements of the Maya could have been satisfied with a mixture of wild animal flesh and wild and cultivated plants including beans. Chaya, Cnidoscolus aconitifolius, domesticated before the Spanish conquest, has a high-protein content and the potential to have been a significant contributor to the ancient Maya diet. Chaya is easily propagated, is grown in home gardens by the Maya today, and is a significant part of the local traditional diet. Chaya's stable isotopic composition of carbon (δ13C) resembles that of other terrestrial plants, but its values for nitrogen (δ15N) are significantly higher. Consumption of chaya would result in slightly higher δ15N values in humans than expected from the consumption of terrestrial animals. Thus, chaya is situated well as a component of the complex, diverse, and varied diets of ancient Mesoamericans.