Diet, depression and anxiety

This study represents the only randomized controlled trial on young adults to date demonstrating that a diet intervention can reduce clinical symptoms of depression. Research is increasingly showing an association between poor diet and depression, while a healthy diet containing fruit, vegetables, fish, whole grains and lean meats and fish are showing an association with positive mental health. This study by Francis et al (2019) enrolled 101 young adults who had both symptoms of depression, and who consumed a poor diet, into two groups: a diet group (placed under a healthy diet intervention) and control group who continued with their habitually poor diet (Editor’s note: complete data for thirty-eight of the 101 individuals was analyzed). Measures were taken at baseline (before intervention) and after the intervention to determine each group’s symptoms of depression, mood, self-efficacy, and memory. The diet group reported lower depressive symptoms after the intervention compared to the control group. In this study, diet intervention reduced depression scores among young adults. [NPID: depression, anxiety, mental health, fruit, vegetables, FV intake, fish, lean meats, whole grains, mood, self-efficacy, memory]

Głąbska et. al (2020) provides us with a systematic review of observational studies focusing on the association between fruit and vegetable intake and mental health in pre-schoolers and school-aged children. A total of 12 studies were picked out from the Pubmed and Web of Science databases, all of which were in English and dated up to June 2019. These studies included fruit and/or vegetables and products like juices, and various aspects of mental health such as general well-being, behavioural difficulties and problems, depressive symptoms, emotions, stress, or even depressive symptoms combined with anxiety. The researchers found that in most of the relevant studies, enhanced fruit and vegetable intake had a positive effect on mental aspects of health in pre-schoolers and school-aged children, although the reviewer urges more research on the area in a new sample group, and also points out many studies ended up recommending a generally more healthy dietary pattern rather than increasing fruit and vegetable consumption alone. [NPID: depression, anxiety, mental illness, FV intake, fruit, vegetables, children, well-being, behavioral difficulties, dietary pattern]

While observational studies are demonstrating an association between healthy dietary intake and mental health, this study aimed to elucidate some of the biological mechanisms underpinning this association. Specifically, the study examined the relationship between dietary patterns, BMI (Body Mass Index), and mental health. The study’s author and her colleagues (2018) collected data from 843 adolescents at age 14 and 17 respectively, along with BMI (body mass index) and biomarkers of inflammation (the hormone leptin and C-reactive protein). Findings indicated that a high intake of Western foods, including meat, takeaway foods, refined foods, and sugary foods, at the age of 14 was associated with a higher BMI. And that this higher BMI, by the age of 17, was associated with not only higher BMI, but higher biological markers of inflammation, depressive symptoms and mental health problems. This study provided increased understanding of some of the biological pathways occurring from the Western dietary pattern that connect this pattern with depression and mental health issues in adolescents. [NPID: depression, anxiety, mental illness, inflammation, leptin, C-reactive protein, meat, refined foods, sugary foods, sugar, Western-style diet, WS diet]

This robust systematic review scoured through around 1000 research articles from 5 decades to find out for us the relevance of good quality diets and eating habits with positive psychological health at all ages including adolescence. After analysing 56 relevant studies, Khanna et. al (2019) finds considerable differences in mental well-being depending on diet (consuming fruits and vegetables, fish, olive oil, nuts, and certain dairy products can positively affect depressive symptoms), whereas the western dietary patterns and behaviours have been linked with increased risk of depression. This current study proposes greater consideration of dietary requirements in the prevention and treatment of mental disorders. [NPID: depression, anxiety, mental illness, well-being, diet quality, children, adolescence, psychological health, Western-style diet, WS diet]

In this self-reported study, 171 low fruit and vegetable-consuming young adults (aged 18-25) were assessed over a 14-day period to determine the psychological advantage of increasing the amount of fruit and vegetables (FV) in their diet. There were 3 groups involved in this study: the control group maintained on their usual diet; “EMI” group given text message reminders to eat more FV (fruits and vegetables) and a voucher to spend on FV; and an “FVI” group who were provided with 2 extra portions of FV to supplement their normal diet. The psychological measures reported every night by the participants were: depressive symptoms and anxiety measured pre- and post-intervention, and daily negative and positive mood, vitality, flourishing, and flourishing behaviors (curiosity, creativity, motivation). The findings included better mental outcomes when young adults were given extra fruit and vegetables (FVI) rather than the method reminding people to increase their FV intake (EMI). Although there was no significant difference in their signs of depression, anxiety or mood over the 14 days, a rise in vitality, motivation and flourishing were seen in these young adults. [NPID: depression, anxiety, mental illness, fruit, vegetable, FV intake, vitality, motivation, flourishing]

Mikolajczyk and his team (2009) conducts a cross-sectional multinational survey on first-year university students in Germany, Poland and Bulgaria to draw comparisons between nutritional intake, stress and depressive symptoms, and to explore any variations between the results of each country. The tests conducted on the students include the Cohen’s Perceived Stress Scale (to assess stress levels), a 12-item food frequency questionnaire (looking at diet quality), and a modified Beck Depression Index (to rate depression levels). The results demonstrated a variation in all 3 factorial tests between the countries and gender. None of the male student groups were linked to perceived stress or depression risk, whereas, higher perceived stress reported could be related to more frequent intake of sweets and fast food. A decrease in fruit and vegetable consumption was also associated with depressive symptoms in the female students. [NPID: depression, anxiety, mental illness, Germany, Poland, Bulgaria, stress, depressive symptoms, diet quality, fruit, vegetables, FV intake]

In this cross-sectional study, the tie between eating patterns and mental health problems (gauged by the use of the Strengths and Difficulties Questionnaire) was investigated in a young Norwegian population (12-13 years old). Parents reported dietary intake through a modified Food Frequency Questionnaire (FFQ) which was then analysed to determine eating patterns (through principal component analysis). The results showed increased signs of psychiatric and hyperactivity-inattention disorders in adolescents on a less ‘varied Norwegian’ eating pattern, and in those with eating habits high in the ‘junk/convenient’ category, than the children who scored lower in scale. A higher score on a ‘snacking’ eating pattern was also correlated to higher risk of conduct/oppositional disorders than lower scores. The study concluded a strong correlation between diversified nutrient-rich diets and enhanced mental health, and the association between poor dieting and irregularly eating habits with poor mental health outcomes at the adolescent stage, independent of physical activity, sedentary activity and background variability. [NPID: depression, anxiety, mental illness, Norwegian, young adult, adolescence, hyperactivity-inattention disorders, ADHD, snacking, nutrient-rich, sedentary]

Mrug et. al (2019) explore the potential role of sodium and potassium excretion in depression by collecting overnight urine samples from adolescents growing up in low-income urbanised neighbourhoods. Samples were taken at the start of the study from 84 adolescents, half of whom were male, and 95% African-American. Depressive symptoms were self-reported at baseline and at the 1.5 year stage, and comparisons were drawn after adjusting for age, BMI, pubertal development and baselines depressive symptoms. The results showed severe depressive symptoms could be predicted by high sodium and low potassium levels in urine and highlighted no variation in trend between male and female. This implies diets made up of high sodium and low potassium content can predispose adolescents who live in poorer, urban areas to develop symptoms of depression. [NPID: depression, anxiety, mental illness, sodium, potassium, low income, African American]

This longitudinally study analyses bi-directional associations between healthy lifestyles and mood disorders. Young adults (aged 26-31) were assessed at baseline and at the 5 year mark, for diagnosis of depression or dysthymia (persistent depression) and questioned on their lifestyle – (i.e., body mass index (BMI), smoker status, alcohol intake, recreational physical activity and healthy diet). The covariates included age, sex, socio-economic position, parental and marital status, social support, major life events, cardiovascular disease history, and self-rated physical and mental health. Independently of these factors, the risk of experiencing first episodes of mood disorders dropped 22% in those with higher lifestyle scores at baseline. An existing mood disorder at baseline was associated with lower incidence of improvement and greater chance of worsening in lifestyle choices. Healthy lifestyles may be mainly talked about in the promotion of preventing cardiovascular disease but this study implies they are closely related to mood disorders and mental health. [NPID: depression, anxiety, mood, dysthymia, smoking, alcohol, cardiovascular disease]

This study looks at the relationship between fruit and vegetable consumption and mental health in a British population and especially accounting for ethnicity, parenting and socioeconomic situations. 4683 adolescents aged 11-13 were extracted from the British multi-ethnic Determinants of Adolescents (now young Adult) Social well-being and Health (DASH) longitudinal study, and followed up after 3 years. Mental health was assessed through the Strengths and Difficulties Questionnaire as mean Total Difficulty Score (TDS) and participants were classed as probable cases of mental disorders if scores reached 17 (higher indicating increased psychological distress). After questioning the study group on the number of fruits and vegetables (FV) consumed daily, around 60-70% answered <5 portions, 20-30% with <1 servings per day. Data revealed the majority of ethnic minority groups were consuming less FV than their white peers. The value <1 portions of FV a day was still significantly correlated with average TDS in the fully adjusted models, while no effects from ethnicity and gender were detected. Low parental care partially reduced the association between FV and mental health, which could inspire research on parenting interventions and its possible developmental effect on children. [NPID: depression, anxiety, worry, fruit, vegetables, FV intake, Britain, socioeconomic status, psychological distress, children]

The hypothesis of this robust U.S. study was whether fruit and vegetable (FV) consumption during adolescence could be linked to an attenuation in risk of developing depression in adulthood. The 3696 participants of this cohort study were taken from the Add Health Study, and were aged 17 at baseline in 1994-1995, and then were 29 at follow-up taking place between 2007-2008. Depression was measured using Center for Epidemiologic Studies Depression Scale (CES-D), while a questionnaire was completed detailing which fruit and vegetable items were consumed the day before, to determine fruit and vegetable intake. The group with the highest percentage failure to consume fruits and vegetables the day before was those who were classed as depressed at baseline and at follow-up also on the CES-D (31% for fruit, 42% for vegetables). But the association between FV consumption and depression was weakened after repeating in fully adjusted models. Although there was promise of an existing link, further studies are required and the use of different dietary measures could produce more robust evidence. [NPID: depression, anxiety, fruit, vegetables]

The aim of this 2018 study was to uncover the prevalence of depression and unhealthy food consumption among first-year college students, and to evaluate whether there is a link between their depression score and unhealthy food intake frequency. The 1,104 college freshmen (40.3% men; 59.7% women) studying at a public university in Mexico City, were examined on their food consumption (food frequency questionnaire) and depressive symptoms [the 20-item depression scale (CES-D)]. Depressive signs were identified in 18.2% of the men and 27.5% of the women, while the reporting of poor dietary habits were fairly common. Only 39.7% of the student sample practiced vigorous physical activity, and 30.3%, 49%, and 51.8% of participants reported eating fried foods, sweetened drinks, and sugary foods 2-7 times per week, respectively. Logistic regression analysis revealed that women were at more risk of developing depressive symptoms if they did not exercise regularly (< 75 min/week; OR = 1.80, p = 0.017), and frequently consumed fast food (OR= 2.08, p = 0.018), fried food (OR = 1.92, p = 0.01) and sugary food (OR = 2.16, p = 0.001). Lazarevich et al. (2018) could not find an association between food consumption and depression scores among male students, but there was a correlation between depression and low exercise frequency (OR = 2.22, p = 0.006). The researchers suggest that those women vulnerable to depression may use food as a coping mechanism to deal with negative mood. Institutional health promotion and nutritional education programs are encouraged to consider emotion and stress management. [NPID: depression, anxiety, Mexico City, fried food, sweetened drinks, sugar, coping mechanism, negative mood, stress, stress management, emotion]

The aim of this 2020 study was to investigate the association between the variables, nutrition, physical activity (PA), lifestyle behaviors (isolated and combined) with symptoms of insomnia, depression and anxiety among adolescents. A survey was conducted in May 2020 on 1,756 middle school students. Students with low family income, living rurally, with excessive fear, who are female, have a sibling, and those who have been left behind were more likely to have a poorer lifestyle or be in a worse mental state. After controlling for confounding factors, more respondents with both poor nutrition and inactive PA appeared to report insomnia (OR=2.16) and depressive (OR=2.57) symptoms than those with only one behavior or neither of them, indicating the correlation between both poor nutrition and inactive PA with higher prevalence of insomnia, depression and anxiety symptoms. It is therefore crucial that adolescents pursue a healthy lifestyle. [NPID: depression, anxiety, mental health, physical activity, insomnia, fear, rural, rural area, low income, female, siblings, women]

This 2019 study investigated the relationship between dietary patterns and mental health in Chinese adolescents, by administering the Multi-dimensional Sub-health Questionnaire of Adolescents (MSQA) to assess emotional, conduct and social adaptation problems, and by collecting data on eating pattern using the semi-quantitative food frequency questionnaire (SQFFQ). Among 32 Chinese schools across 4 provinces, a total of 14,500 adolescents (in grade 7-12) completed eligible questionnaires. Four main patterns were identified: healthy, meat, sugar-sweetened beverages (SSBs) and fast foods patterns. The healthy pattern was associated with lower risk of psychological symptoms [adjusted odds ratio (aOR) = 0.59, 0.6, 0.62, 0.53, all p<0.01), while the the fast foods pattern (aOR = 2.16, 2.04, 1.84, 2.24, respectively, all p < 0.01), the SSBs pattern (aOR = 1.38, 1.34, 1.25, 1.56, respectively, all p < 0.01) and the meats pattern (aOR = 1.24, 1.15, 1.12, 1.28, respectively, all p < 0.05) were significantly related with increased incidence of psychological symptoms. Dose-response relationships were observed for all dietary patterns with psychological symptoms, except for meat eating patterns. The limitation of this study was that SQFFQ made it difficult to determine the accurate consumption of foods, while Xu et al. (2019) even admitted that they could not infer causality because of the cross-sectional design. Nevertheless, this study emphasized the importance of eating patterns during adolescence in the context of mental health. [NPID: depression, anxiety, mental health, China, healthy, meat, sugar-sweetened beverages, fast food, adolescence]

The aim of this 2021 systematic review was to examine the relationship between fruit and vegetable consumption and depressive symptoms among young people and adults aged 15-45. Although the association between fruit and vegetable intake with mental health has already been identified, there have been limited studies involving young people and adults. A total of 12 studies (found in the systematic search) met the criteria of analyzing fruit and vegetable intake (separately and/or together), with depression or depressive symptoms as the outcomes. One of the studies was of “very good” quality, while nine studies were “good”, and two studies were deemed to be of “moderate” quality based on the measure (Newcastle-Ottawa Scale). Although most of the cohort studies supported the link between fruit consumption and lower risk of developing depression, inconsistencies were identified when analyzing the impact of vegetable intake independently and when the combined effect of fruit and vegetable consumption was evaluated. Nevertheless, the evidence seems to point to the validity of this association. Hopefully this data can be utilized to address the mental illness burden in young people and adults (aged 15-45 years). [NPID: depression, anxiety, depressive symptoms, fruits, vegetables, fruits and vegetables, systematic review, review, young people, adults]

This 2021 study examined the relationship between lifestyle habits and depressive symptoms among a sample of Norwegian adolescents who partook in the Ungdata Surveys in 2017-2019. The survey asked the adolescents (aged 13-19 years) about their depressive behaviors and lifestyle habits (such as physical activity level, social media use, gaming, dietary habits, smoking, smokeless tobacco, and alcohol intoxication). Kleppang et al. found that depressive signs were significantly less likely to be reported by those who took part in some form of physical activity at least 3 times per week, used social media 3 hours or less on a daily basis, played video games 3 hours or less per day, non-smokers, and who hadn’t been intoxicated (alcohol) in the past 12 months. Among the girls, low depressive symptoms showed correlations with high consumption of healthy foods and low intake of unhealthy food and drinks. A similar relationship was observed among the boys. There was also a strong association between higher adherence to healthy lifestyle habits with lower risk of having depressive symptoms among both males and females, with 60% and 48% reduced odds in boys and girls, respectively. This study highlights that a healthier lifestyle is linked with lower chances of having depression. [NPID: lifestyle, depression, anxiety, lifestyle choices, lifestyle habits, Norway, Norwegian, depression, alcohol, smoking, video games, healthy lifestyle, healthy foods]

Mediterranean diet and mental health in university students: an Italian cross-sectional study