Final answer:
A client on oxtriphylline therapy should limit the intake of coffee and chocolate to avoid potential interference with the medication's therapeutic effects due to the presence of caffeine and theophylline, which can stimulate the central nervous system.
Step-by-step explanation:
A client who has begun therapy with oxtriphylline (Choledyl) would need to make specific dietary alterations to avoid any interactions with the medication. The nurse would determine that the client understands these dietary alterations if the client states an intention to limit consumption of certain items. Among the items listed, the client should specifically limit coffee and chocolate. These contain caffeine and theophylline, which can both stimulate the central nervous system. Too much of these substances can lead to excessive nervous system stimulation and side effects, as oxtriphylline is a theophylline-derivative and these can potentially interfere with its therapeutic effects.