Increased fruit & vegetable consumption can enhance mental well-being; both increasing frequency & increasing quantity matter; a hump-shaped relationship appeared between age & fruit & vegetable consumption

Lettuce be happy: A longitudinal UK study on the relationship between fruit and vegetable consumption and well-being. Neel Ocean, Peter Howley, Jonathan Ensor. Social Science & Medicine, https://doi.org/10.1016/j.socscimed.2018.12.017

Highlights
•    Increased fruit & vegetable consumption can enhance mental well-being.
•    Increasing frequency and increasing quantity of consumption both matter.
•    The relationship is robust to different measures of well-being.
•    A hump-shaped relationship appeared between age and fruit and vegetable consumption.

Abstract
Rationale: While the role of diet in influencing physical health is now well-established, some recent research suggests that increased consumption of fruits and vegetables could play a role in enhancing mental well-being. A limitation with much of this existing research is its reliance on cross-sectional correlations, convenience samples, and/or lack of adequate controls.

Objective: We aim to add to the emerging literature on the relationship between fruit and vegetable consumption and well-being by using longitudinal data from a study in the United Kingdom (UK).

Method: We employ panel data analytical techniques on three waves collected between 2010 and 2017 (i.e., following the same individuals over time) in the UK Household Longitudinal Survey. We also control for time-variant confounders such as diet, health, and lifestyle behaviours.

Results: Fixed effects regressions show that mental well-being (GHQ-12) responds in a dose-response fashion to increases in both the quantity and the frequency of fruit and vegetables consumed. This relationship is robust to the use of subjective well-being (life satisfaction) instead of mental well-being. We also document a hump-shaped relationship between fruit and vegetable consumption and age.

Conclusion: Our findings provide further evidence that persuading people to consume more fruits and vegetables may not only benefit their physical health in the long-run, but also their mental well-being in the short-run.