Consumption of Dietary Guidelines for Americans Types and Amounts of Vegetables Increases Mean Subjective Happiness Scale Scores: A Randomized Controlled Trial

Abstract

BackgroundThe health benefits of diets rich in fruits and vegetables (FV) are well established. Recent observational and intervention research suggests that FV consumption may also exert a positive effect on psychological well-being. ObjectiveThis study aimed to assess changes in mean Subjective Happiness Scale (SHS) scores in response to consuming 2010-2015 Dietary Guidelines for Americans (DGA) recommended types and amounts of vegetables. It was hypothesized that increased vegetable consumption would increase mean SHS scores. DesignThis study investigated a secondary outcome of a randomized, parallel, nonblinded controlled trial with a 1:1 allocation ratio to a provided vegetable intervention or attention control group. Participants/settingMen and women (n = 75) aged 18 to 65 years, body mass index ≥ 25, with low habitual vegetable consumption were recruited from Grand Forks, North Dakota, December 2016 to January 2018, for this community-based study. InterventionThe vegetable intervention consisted of an 8-week feeding phase during which participants were provided with vegetables in DGA-recommended types and amounts. The attention control group was not provided vegetables but completed the same testing schedule as the vegetable intervention group. Main outcome measureMean SHS scores were assessed before and after the intervention. Statistical analysesMean SHS scores were analyzed using a 2-way factorial mixed linear model analysis of variance. ResultsA significant interaction between treatment and visit (P = .015) revealed greater mean SHS scores at week 8 than at baseline in the vegetable intervention group (+0.23 ± 0.11) (mean difference ± SE of the difference) but no change in the attention control group (−0.15 ± 0.11). ConclusionsGreater mean SHS scores were observed after increasing vegetable consumption to meet DGA recommendations, suggesting that adhering to DGA vegetable guidance may help promote psychological well-being.