By James Kwak
From the treasure trove that is the NBER working paper series, a friend forwarded me “Is Psychological Well-Being Linked to the Consumption of Fruit and Vegetables?” by David Blanchflower, Andrew Oswald, and Sarah Stewart-Brown (NBER subscription required). It got some media attention last month when the paper first came out, but I wanted to read it because, well, I eat a lot of fruits and vegetables: I generally aim for seven servings a day, although when life is busy it can be as low as three or four. (Right now I’m munching on dried mango slices.)
The core of the paper is a bunch of regressions that show that better psychological well-being (which is all the rage these days) is correlated with eating more fruits and vegetables, with benefits up to at least five servings and in some cases up to eight servings. This isn’t particularly surprising on its face, since eating fruits and vegetables is probably correlated with having a high income, exercising, being fit, cooking, and any number of other things that are conducive to happiness.
But the relationship persists even when you control not for the usual things—age, gender, race, marital status, income—but even when you control for things like education, religion, health status, body mass index, smoking, sexual activity, exercise, marital status, number of children, disability status, and employment status. (See Table 1, column 3.) This is surprising, at least to me, since it says that fruits and vegetables make you happy in some way other than making you healthier and more fit.
It’s still quite possible that the mechanism at work isn’t the fruits and vegetables themselves but something else that correlates with consumption of fruits and vegetables. I suspect that people who eat fruits and vegetables tend to be those with more time on their hands (even within the group of employed people) and who put more effort into taking care of themselves. But just in case it is the fruits and vegetables themselves, go eat an extra apple or banana. We already know that eating less meat is good for the environment, anyway.