Is there an association between diet and depression in children and adolescents? A systematic review

Does the Mediterranean Diet Protect against Stress-Induced Inflammatory Activation in European Adolescents? The HELENA Study

Stress increases inflammation but whether adherence to Mediterranean diet counteracts this association and how early can these effects be observed is not well known. We tested whether (1) cortisol is associated to inflammation, (2) cortisol is associated to the adolescent Mediterranean diet score (aMDS), (3) aMDS lessens inflammation, (4) aMDS associates with cortisol levels and inflammation. Two hundred and forty-two adolescents (137 females; 12.5⁻17.5 years old) provided salivary cortisol, blood and 2-day 24-h dietary recall from which aMDS was derived. Cortisol levels were associated with increased tumor necrosis factor (TNF-α B = 11.887, p = 0.001) when adjusted for age, gender, parental education and body mass index (BMI). Moreover, cortisol levels were inversely associated to adherence to the Mediterranean Diet (B = -1.023, p = 0.002). Adolescents with higher adherence to aMDS had lower levels of interleukins (IL) IL-1, IL-2, IL-6 and TNF-α, compared to those who did not adhere. The association between cortisol and TNF-α was no longer significant when aMDS was included in the model (B = 6.118, p = 0.139). In addition, comparing lower and higher aMDS groups, the association between cortisol and TNF-α was only observed in those with lower aMDS adherence. Our study suggests that adherence to the Mediterranean Diet may counteract the effect of stress on inflammatory biomarkers which may contribute to decreasing the risk of future mental health.

Poor Dietary Habits in Bullied Adolescents: The Moderating Effects of Diet on Depression

The prevalence of bullying has increased dramatically during recent years, with numerous negative consequences for the health and quality of life of bullied adolescents. Although negative psychological consequences of this type of situation have been widely investigated, no previous research has evaluated the effects of bullying victimization on dietary habits, and its relationship with psychological outcomes, such as depression. For this reason, the main aim of the present study was to evaluate the association between bullying, dietary habits, and depression in a sample of 527 Spanish adolescents. The results obtained showed that being bullied was correlated negatively with healthy dietary habits and positively with depression. Moderation analysis revealed dietary habits as moderator of the association between bullying and depression. These results underline the relevance of diet in the phenomenon of bullying, especially in victims, as could be related to the high levels of depression characteristic of this population. The inclusion of nutritional education in intervention programs oriented to victims of bullying might significantly improve their efficacy, reducing depression levels.

Diet quality and depressive symptoms in adolescence: no cross-sectional or prospective associations following adjustment for covariates

OBJECTIVE

Adolescence is a critical period for development of depression and understanding of behavioural risk factors is needed to support appropriate preventive strategies. We examined associations between adolescent diet quality and depressive symptoms, cross-sectionally and prospectively, in a large community cohort, adjusting for behavioural and psychosocial covariates.

DESIGN

Prospective community-based cohort study (ROOTS).

SETTING

Secondary schools in Cambridgeshire and Suffolk, UK.

SUBJECTS

Study participants (n 603) who completed 4 d diet diaries at age 14 years and reported depressive symptoms (Moods and Feelings Questionnaire (MFQ)) at 14 and 17 years of age.

RESULTS

Diet data were processed to derive a Mediterranean diet score (MDS) and daily servings of fruit and vegetables, and fish. At age 14 years, a negative association between fruit and vegetable intake and MFQ score was seen in the unadjusted cross-sectional regression model (β=-0·40; 95 % CI -0·71,-0·10), but adjustment for behavioural covariates, including smoking and alcohol consumption, attenuated this association. Fish intake and MDS were not cross-sectionally associated with MFQ score. No prospective associations were found between MDS, fruit and vegetable intake or fish intake and later MFQ score.

CONCLUSIONS

Diet quality was not associated with depressive symptoms in mid-adolescence. Previously reported associations in this age range may be due to confounding. Further longitudinal studies are needed that investigate associations between adolescent diet and depression across different time frames and populations, ensuring appropriate adjustment for covariates.

The Role of Dietary Patterns in Mood Disorders: Prospective Research in Youth Populations

Childhood mood disorders, including depression and bipolar spectrum disorders, represent serious public health concerns and often extend into adulthood. Due to increasing rates of a mood disorder diagnosis, and its accompanying risk of suicide, identification and management in childhood and adolescence is critical. Yet, fully effective and safe treatment options are lacking for child-onset mood disorders. Research investigating relationships between nutrition and psychiatry is a plausible avenue to improve prevention and treatment options. Epidemiological and observational evidence exists to support a protective effect of the Mediterranean diet in mood disorder prevalence and future diagnosis. To date, the majority of research has been conducted in adult populations. Future research is needed to examine if similar dietary relationships exist within a youth mood disorder population. Additionally, increased homogeneity in assessment methods of mood disorder symptoms and dietary patterns is needed; specifically, to determine more collective conclusions via meta-analyses. Results from youth studies could be used to formulate future randomized controlled trials, health promotion programs or clinical interventions, via diet or supplement interventions, for alternative mood disorder treatment or prevention purposes.

Diet quality and depression risk: A systematic review and dose-response meta-analysis of prospective studies

BACKGROUND

It has been claimed that the quality of a diet is associated with the incidence of depressive disorders. We sought to investigate the evidence for this claim.

METHODS

Systematic searches were performed up to March 6th, 2017 in order to identify prospective cohort studies that reported on exposure to dietary patterns or food groups and the incidence of depression/depressive symptoms. Data from 24 independent cohorts (totalling 1,959,217 person-years) were pooled in random-effects meta-analyses.

RESULTS

Adherence to a high-quality diet, regardless of type (i.e., healthy/prudent or Mediterranean), was associated with a lower risk of depressive symptoms over time (odds ratios ranged 0.64-0.78 in a linear dose-response fashion [P < 0.01]). A relatively low dietary inflammatory index was also associated with a somewhat lower incidence of depressive symptom (odds ratio = 0.81), although not in a dose-response fashion. Similar associations were found for the consumption of fish and vegetables (odds ratios 0.86 and 0.82 respectively) but not for other high quality food groups (e.g., fruit). Studies that controlled for depression severity at baseline or that used a formal diagnosis as outcome did not yield statistically significant findings. Adherence to low quality diets and food groups was not associated with higher depression incidence.

LIMITATIONS

Our ability to detect confounders was only limited.

CONCLUSION

There is evidence that a higher quality of a diet is associated with a lower risk for the onset of depressive symptoms, but not all available results are consistent with the hypothesis that diet influences depression risk. Prospective studies that control for relevant confounders such as obesity incidence and randomized controlled prevention trials are needed to increase the validity of findings in this field.

Adherence to a Dash-style diet in relation to depression and aggression in adolescent girls

The aim of this study was to assess adherence to the Dietary Approach to Stop Hypertension (DASH) dietary pattern in relation to depression and aggression in adolescent girls. The study was carried out among 580 girls aged between 12 and 18 years of age. DASH scores were determined according to the method of Fung et al. A Persian version of the Beck Depression Inventory and Buss-Perry questionnaire were used for the assessment of depression and aggression. We analysed our data using crude and adjusted models. Adjustments were made for age, energy intake, mother's job status, passive smoking, start of menstruation, parental death, parental divorce, physical activity level and body mass index, using three different models. A high adherence to a Dash-style diet (for individuals in the upper quartile) was associated with a lower odds of depression compared with subjects with lower adherence (those in the lowest quartile) (OR 0.47; 95% CI 0.26-0.84, P-value = 0.009); these associations remained significant after adjustments. However, we did not obtain any significant relationship between a DASH-style diet and aggression. We observed a significant inverse relationship between greater adherence to a DASH diet and lower odds of depression. Further prospective studies are needed to confirm these findings.

Does Fruit and Vegetable Consumption During Adolescence Predict Adult Depression? A Longitudinal Study of US Adolescents

The relationship between better diet quality and decreased depression across the life span is consistent and compelling. Fruit and vegetable consumption has been of particular interest. The nutritional benefits from the consumption of fruits and vegetables may mitigate non-communicable diseases and promote brain and mental health. This study aimed to determine whether fruit and vegetable consumption during adolescence was associated with a reduced risk of developing depression in adulthood in a large, representative sample of US individuals. Data from the Add Health Study were analyzed, which included 3,696 participants who were aged approximately 17 years at baseline (1994-1995), and 29 years at follow-up (2007-2008). The Center for Epidemiologic Studies Depression Scale was used to assess depression and a self-report item asked how many times the participant consumed fruit/vegetables on the previous day. Individuals who were depressed at both times points had the highest proportion who failed to consume any fruit (31%) or vegetables (42%) on the previous day. Fruit and vegetable consumption did not predict of adult depression in fully adjusted models. Cross sectional associations existed for diet and adolescent depression only. Our initial findings supported fruit and vegetable consumption as being protective against adult depression, but this association was subsequently attenuated on adjustment for other relevant factors. Future research will benefit from more precise measures of dietary intakes.

Dietary behaviour, psychological well-being and mental distress among adolescents in Korea

BACKGROUND

Dietary intake is important for physical and mental health. The aim of this investigation was to assess associations between dietary behaviours and psychological well-being and distress among school-going adolescents in Korea.

METHODS

In a cross-sectional nationally representative survey, 65,212 students (Mean age = 15.1 years, SE = 0.02 and 52.2% male and 47.8% female) responded to a questionnaire that included measures of dietary behaviour, psychological well-being and mental distress.

RESULTS

In logistic regression analyses, adjusted for age, sex, socioeconomic status, school level, school types, Body Mass Index, physical activity, and substance use, positive dietary behaviours (regular breakfast, fruit, vegetable, and milk consumption) were positively and unhealthy dietary behaviours (intake of caffeine, soft drinks, sweet drinks and fast food consumption) were negatively associated with self-reported health, happiness and sleep satisfaction. Positive dietary behaviours (regular breakfast, fruit, vegetable, and milk consumption) were negatively associated with perceived stress and depression symptoms. Unhealthy dietary behaviours (consumption of fast food, caffeine, sweetened drinks and soft drinks) were associated with perceived stress and depression symptoms.

CONCLUSIONS

The study found strong cross-sectional evidence that healthy dietary behaviours were associated with lower mental distress and higher psychological well-being. It remains unclear, if a healthier dietary behaviour is the cause or the sequela of a more positive well-being.

Effects of Acute Blueberry Flavonoids on Mood in Children and Young Adults

Epidemiological evidence suggests that consumption of flavonoids (usually via fruits and vegetables) is associated with decreased risk of developing depression. One plausible explanation for this association is the well-documented beneficial effects of flavonoids on executive function (EF). Impaired EF is linked to cognitive processes (e.g., rumination) that maintain depression and low mood; therefore, improved EF may reduce depressionogenic cognitive processes and improve mood. Study 1: 21 young adults (18–21 years old) consumed a flavonoid-rich blueberry drink and a matched placebo in a counterbalanced cross-over design. Study 2: 50 children (7–10 years old) were randomly assigned to a flavonoid-rich blueberry drink or a matched placebo. In both studies, participants and researchers were blind to the experimental condition, and mood was assessed using the Positive and Negative Affect Schedule before and 2 h after consumption of the drinks. In both studies, the blueberry intervention increased positive affect (significant drink by session interaction) but had no effect on negative affect. This observed effect of flavonoids on positive affect in two independent samples is of potential practical value in improving public health. If the effect of flavonoids on positive affect is replicated, further investigation will be needed to identify the mechanisms that link flavonoid interventions with improved positive mood.