An example of a class of antinutritents would be negative roles in nutrition of tannins in grain sorghum for instance. To look at such issues a wide array of genotypes can be assayed for this character and then assay undertaken on the association with nutritional results from feeding trials. Another approach is to take genotypes without the antinutrient class than add the class compounds at different levels and trial the nutritional response. Another variant would be taking a high tannin grain type then extracting the materials to detoxify and than trial through test organism. In a model sense the use of cell culture or microorganism might be used for a model of test response to improve the ease of testing and lower the expense. The defensive compounds which have unwanted effects can also have positive effects in some cases. Much of the work on health promoting properties is focusing on plant secondary metabolites.