Family caregivers play a critical role in dietary care and the nutritional status of people with dementia. The aim of this study was to investigate the effects of a family care-based dementia dietary educational program (DDEP) on family caregivers’ nutritional knowledge, healthy eating behavior and nutritional status of people with dementia. A total of 57 pairs of participants completed this longitudinal experimental study. Group A received routine care. Group B received the DDEP. Three outcomes were measured at pretest (T1), posttest (T2) and follow-up test (T3).