Information on eating situation and location is particularly important to develop effective programs for preventing depression; thus, these factors warrant further research. Third, as information was missing on factors such as personality traits, appetite and the presence of family members requiring nursing care, confounding factors may not have been fully taken into account. Nonetheless, we were able to control for the potential confounding effects of social relationships. Given the number of potentially confounding factors that we could not account for, our results should be interpreted with some caution. Fourth, we lacked data on antidepressant drug use, which may have biased the association between eating status and depression; for example, subjects who eat with others may be more likely to be recognised as depressed and receive treatment.