Eat veggies, be happy! Consumption of Dietary Guidelines for Americans types and amounts of vegetables increases subjective happiness: A randomized controlled trial

Authors: DE LEON, ANGELA - Former ARS Employee; JAHNS, LISA - National Institute Of Food And Agriculture (NIFA); Roemmich, James; Casperson, Shanon

Submitted to: Journal of the Academy of Nutrition and Dietetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2021
Publication Date: 11/15/2021
Citation: De Leon, A., Jahns, L., Roemmich, J.N., Casperson, S.L. 2021. Eat veggies, be happy! Consumption of Dietary Guidelines for Americans types and amounts of vegetables increases subjective happiness: A randomized controlled trial. Journal of the Academy of Nutrition and Dietetics. 122:1355-1362. https://doi.org/10.1016/j.jand.2021.11.009.
DOI: https://doi.org/10.1016/j.jand.2021.11.009

Interpretive Summary: In addition to the well-known health benefits of eating fruits and vegetables, eating them may also exert a positive effect on psychological well-being. This study aimed to determine if eating the Dietary Guidelines for Americans (DGA) recommended types and amounts of vegetables exerts a positive effect on how happy a person feels. Overweight and obese men and women (18-65 years of age) who reported that they ate no more than one serving of vegetables each day participated in this community-based study. Participants were assigned to either a vegetable intervention or a control group. The vegetable intervention consisted of an 8-week feeding phase during which participants were provided with vegetables according to DGA recommendations. The attention control group was not provided vegetables but completed the same testing schedule as the vegetable intervention group. The Subjective Happiness Scale questionnaire was used to assess happiness before and after the intervention. We found that happiness scores were greater after increasing vegetable consumption to meet DGA recommendations. This finding was independent of baseline happiness scores. Happiness scores did not change in the control group. These findings suggest that eating DGA recommended types and amounts of vegetables may promote psychological well-being and further emphasizes the importance of following DGA guidance.

Technical Abstract: Background: The health benefits of diets rich in fruits and vegetables (FV) are well established and form the basis of the Dietary Guidelines for Americans (DGA). Furthermore, FV consumption may also exert a positive effect on psychological well-being. Objective: This study aimed to assess changes in global subjective happiness when consuming DGA recommended types and amounts of vegetables. It was hypothesized that increased vegetable consumption would increase happiness. Design: This study investigated secondary outcomes of a randomized, parallel, non-blinded controlled trial with a 1:1 allocation ratio to a provided vegetable intervention or attention control group. Participants/setting: Men and women aged 18-65 yr, body mass index = 25 kg/m2, with low habitual vegetable consumption were recruited for this community-based study. Intervention: The 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 measure: The Subjective Happiness Scale (SHS) was used to assess individual perceived happiness before and after the intervention. Statistical analyses: SHS scores were analyzed using a mixed model analysis of variance both with and without baseline SHS scores as a covariate. Results: A significant interaction between treatment and visit (P = 0.005) revealed greater happiness at week 8 than at baseline in the vegetable intervention group but no change in the attention control group. When adjusted for baseline scores, a significant effect of treatment (P = 0.005) was found with greater happiness scores in the vegetable intervention group compared to the attention control group post intervention (P < 0.001). Conclusions: Greater subjective happiness was observed after increasing vegetable consumption to meet DGA recommendations, suggesting that adhering to DGA guidance may promote psychological well-being.