Functional food consumption and depression among the elderly — What can we learn from a longitudinal survey?

Depressive syndromes among the elderly have been recognized as important public health issues. This study contributes to this issue by investigating the causal effect of functional food consumption on depression among the elderly using a unique panel dataset of 1480 individuals drawn from a national representative survey of Taiwanese elderly in 1999, 2003 and 2007. In addition to estimating a standard individual fixed effect model, a random trend fixed effect model which allows for both unobserved individual-specific time invariant and variant factors is estimated. The results of the random trend model point to a significant and negative effect of functional food consumption on depression among the elderly. However, an insignificant effect is predicted by the standard fixed effect model. In addition to functional food consumption, living arrangement with children and engagement in the social activities of the elderly also significantly decrease the likelihood of the elderly becoming depressed.