Diet and Mood

This 2017 study recruited 171 low fruit and vegetable (FV)-consuming young adults (aged 18-25), and randomly assigned them into one of three conditions: an ecological momentary intervention (EMI) involving text message reminders to increase FV intake as well as vouchers to buy FV; fruit and vegetable intervention (FVI) providing the subjects with two additional servings of FV on top of their regular diet; and the control condition which was the participants’ normal day-to-day diet. The purpose was to research the effects of these 14-day interventions promoting greater FV consumption. Depressive and anxiety symptoms were measured pre- and post-intervention while positive mood, vitality, flourishing and flourishing behaviors (curiosity, creativity, and motivation) were documented on a nightly basis using a smartphone survey. Blood samples were taken before and after the interventions took place to examine vitamin C and carotenoid levels. In addition, psychological expectancies about the benefits of FV were taken to test as mediators of psychological change. The results showed improvements in psychological well-being (increases in flourishing, vitality and motivation) in only the group that received 2 supplementary portions of fruits and vegetables (the FVI intervention group), across the 14 days relative to the other condition groups. Intervention benefits were not mediated by vitamin C, carotenoids, or psychological expectancies but this study demonstrated young adults react more positively to provision of high-quality, fresh fruits and vegetables, rather than reminders and vouchers to encourage increased FV intake. Significant short-term improvements in their psychological well-being were seen, which provides early proof-of-concept that giving young adults fruits and vegetables to eat can have psychological benefits even over a short period of time.

(2016) In this study, 541 Iranian students took part in online questionnaires to analyze their measure of contentment associated with their fruit and vegetables intake, and whether they skipped breakfast or not. The results showed several statistically significant links, namely, greater levels of happiness were achieved in those who ate breakfast, consumed more fruit and vegetables, and who ate an increased number of meals a day.

(2015) This was a correlational study that aimed to investigate whether there is a relationship between fruit and vegetable intake and our “eudaemonic” state (which is a mental state that relates to happiness and includes feelings of curiosity, creativity, happiness, engagement, and purpose). The study had 405 young adults complete an internet diary for 13 days which recorded their mood (positive or negative), and the amount of fruit, vegetables and less nutrient-dense foods they consumed (i.e., chips and sweets). A significant relationship between eating fruits and vegetables and higher eudaemonic well-being was found. This study contributes to the growing body of knowledge that helps us understand the relationship between diet and mental health which is not only created by lack of disease, but also by presence of well-being.

(2019) Adherence to the “high quality” Mediterranean diet (MD) and mental well-being were examined in a group of Spanish children and adolescents. They were cross-sectionally analysed at the start of the study and after a 2-year interval (533 children and 987 adolescents initially, 527 children and 798 adolescents at follow-up). The aim of the study was to assess the relationship between MD adherence (using KIDMEX Index) and psychological health (with the Positive and Negative Affect Schedule and the KIDSCREEN-10 questionnaire) by adopting a multi-level, mixed-effects linear regression model. Cross-sectional analysis highlighted that increased MD adherence behaves as a protective factor for positive mental well-being.

(2019) Health-related quality of life (HRQOL) and subjective happiness of 527 Spanish adolescents were evaluated along with their adherence to the Mediterranean Diet (MD). The use of Pearson’s correlations and hierarchical linear regression analysis supported a positive association of MD adherence with higher HRQOL and subjective happiness scores. Several subscales of HRQOL such as emotional well-being, mood and emotions, financial resources and social acceptance were seen to have a mediation effect in the association between MD adherence and subjective happiness after employing the macro PROCESS for SPSS. Ferrer-Cascales et al encourages further research on other factors that may mediate the association found in this study.

(2019) This study examined whether there was a correlation between diet and mood during menstrual cycles in Chinese University students. Through random sampling, 88 academics from Guangzhou were selected to take part in 2 self-administered questionnaires: one documented their eating habits; another evaluated level of negative mood. Multiple logistic regression analyses were used to discover statistically significant lower mood scores during the menstrual phase when consumption of tea, coffee, and carbonated beverage was higher. During the premenstrual phase, worsening of mood was associated with banana and red Chinese dates intake (statistically significant). This study suggests specific foods and diets may influence mood in post-pubescent women.

(2013) This study looked at whether positive affect (mood) plays a role in people consuming healthier food. The authors wanted to understand whether positive moods drive us towards selecting healthier foods. Data was collected from the daily diaries of 281 healthy young adults across 21 days. Their food intake and positive and negative mood was recorded. Analysis of daily associations between diet and mood revealed a significant increase in fruit and vegetable consumption in adults who experienced positive moods. The results also demonstrated that fruit and vegetable intake could influence psychological mood experienced the following day, and to an even greater extent when 7-8 portions of F+V were consumed.

(2017) This was a correlational study examined the association between dietary intake quality and depressive symptoms in female university students. This population (female young adults) is at a greater risk for developing both unhealthy lifestyle habits and depressive symptoms, and therefore, it is important to identify whether consuming healthy food is in any way associated with the mental health of this population. The dietary intake of 141 female university students was collected in the fom of 3-day food journals. The students were assessed for depressive symptoms by questionnaire. Results showed that increased depression scores positively associated with the consumption of a low-nutrient diet in this sample population. Editor’s note: see Francis et al’s study (CNP’s featured Parent Library study) which is the first study to demonstrate the ability of poor diet to cause depressive symptoms in young adults.

The aim of this intervention study conducted by Smith & Rogers (2014) was to examine the interaction between well-being and types of snacks (chocolate/crisps vs fruit) consumed. The 100 student volunteers (average age 19, 27 males; 73 females) completed online questionnaires at baseline measuring anxiety and depression, fatigue, somatic symptoms, cognitive difficulties and distress before being randomly assigned to one of two snacking conditions (chocolate/crisps or fruit). The volunteers were given 1 snack mid-afternoon each day for 10 days before taking the online questionnaires again. At baseline, chocolate consumption was linked with greater emotional eating and depression, while post-intervention analyses indicated an association between eating fruit with lower anxiety, depression, and emotional distress, compared to chocolate and crisps consumption. Those volunteers who were given chocolate/crisps also scored higher in cognitive difficulties, fatigue and somatic symptoms, further emphasizing the benefits of consuming fruits, rather than unhealthy snacks, on health outcomes. These results support the findings from cross-sectional studies and mark the importance of choosing snack type in achieving mental well-being.

This study analyzed the relationship between adherence to the Mediterranean Diet (MD) and emotional well-being among University of Granada students in Spain, through descriptive, exploratory, transversal and correlational methods. Diet adherence was measured with the PREvencion con DIetaMEDiterranea (PREDIMED) questionnaire while emotional well-being (both positive and negative affection) was gauged with the Spanish version of the Positive and Negative Affect Schedule (PANAS), the state of perceived health was evaluated with the Short Form-36 (SF36), and the degree of physical activity was determined by administering the International Physical Activity Questionnaire Short Form (IPAQ-SF). There was a significant association found between strict adherence to the MD and positive emotional state (β = 0.018, p = 0.009). Results also indicated that perceived state of health (β = 0.192, p < 0.001), mental role (β = 0.346, p < 0.001), and physical activity (β = 0.155, p = 0.007) were predictive factors of a positive emotional state. Although adherence to MD and negative emotional state was not found to be significantly associated with one another, various components of the MD were independently connected to psychological well-being, suggesting that strict implementation of a nutritious diet such as the MD can enhance one’s emotional health.

In this 2013 study, 6,528 students (grade 5) in Canada were examined to explore the relationship between their diet quality and feelings of worry, sadness or unhappiness. The students’ responses to the Harvard Food Frequency Questionnaire were used to calculate a composite score of diet quality and its components (variety, adequacy, moderation and balance), while the outcomes of this experiment were their responses to the question on “feelings of worry, sadness or unhappiness” from the EuroQoL 5 Dimension questions for Youth (EQ-5D-Y), which is a validated Health Related Quality of Life questionnaire. Logistic regression analyses showed an inverse association between diet quality with the children’s feelings of worry, sadness or happiness (odds ratio = 0.9). Moreover, greater dietary variety and adequacy also correlated with lower odds of feeling worried, sad or unhappy. Diet had a more marked impact on these feelings in the girls compared to the boys, after results were stratified by gender. While supporting the link between diet and mental health described in other studies, these findings suggest that the quality of diet can have an impact on children’s feelings of worry, unhappiness and sadness. Public health strategies aiming to manage/prevent mental health in children and youth may want to consider diet quality.

Khalid et al. (2017) explain that flavonoid consumption may reduce the risk of developing depression due to its positive impacts on executive function (EF) already reported. Since weak EF is linked to cognitive processes that maintain depression and low mood, greater EF may signify less depressionogenic cognitive processes and better mood. In the first counterbalanced crossover study, 21 young adults (18-21 years old) consumed a flavonoid-enriched drink as well as a matched placebo, while the second study involved random allocation of 50 children (7-10 years old) to drink either a flavonoid-rich blueberry drink or a matched placebo. Both were double-blind studies and utilized the Positive and Negative Affect Schedule to measure the participants’ mood before and 2 hours after drink consumption. The blueberry intervention was found to increase positive affect in both studies but it had no impact on negative affect. This promising effect of flavonoids on positive affect, observed in 2 different samples, could be of potential value in improving public health. Additional research may be warranted to describe the mechanism(s) in which flavonoid interventions enhance positive mood.

Fruit and vegetables intake in adolescents and mental health: a systematic review

Role of fruit and vegetables for the mental health of children: a systematic review