Humans run on a fuel called food. Yet economists and other social scientists rarely study what people eat. We provide simple evidence consistent with the existence of a link between the consumption of fruit and vegetables and high well-being. In cross-sectional data, happiness and mental health rise in an approximately dose-response way with the number of daily portions of fruit and vegetables. The pattern is remarkably robust to adjustment for a large number of other demographic, social and economic variables. Well-being peaks at approximately 7 portions per day. We document this relationship in three data sets, covering approximately 80,000 randomly selected British individuals, and for seven measures of well-being (life satisfaction, WEMWBS mental well-being, GHQ mental disorders, self-reported health, happiness, nervousness, and feeling low).
One major note: the researchers caution that reverse causality may be an issue. That is, rather than fruit and vegetables causing well-being, it may be that well-adjusted people prefer eating a lot of fruit and vegetables. The authors recommend additional "randomized trials to explore the consequences for mental health of different levels of fruit-and-vegetable consumption."