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Cited by 475Nutritional Studies and DietFatty Acid Research and HealthNutrition, Health and Food Behavior

Food and mood: How do diet and nutrition affect mental wellbeing?

Open access
Firth, Joseph, Gangwisch, James E, Borsini, Alessandra, Wootton, Robyn E, Mayer, Emeran A·2020·BMJ
DOI 10.1136/bmj.m2382PMC PMC7322666
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Abstract

Poor nutrition may be a causal factor in the experience of low mood, and improving diet may help to protect not only the physical health but also the mental health of the population, say Joseph Firth and colleagues

AI snapshot

Written from the paper’s full text.

TL;DR

Poor nutrition may be a causal factor in low mood, and healthy dietary patterns such as the Mediterranean diet are associated with better mental health than “unhealthy” Western diets. Proposed mechanisms include glycaemia, immune activation, and the gut microbiome, but causal pathways and clinical applications remain uncertain.

Key findings

  • Healthy eating patterns, such as the Mediterranean diet, are associated with reduced risk of depression, whereas “unhealthy” eating patterns are linked to poorer mental health.
  • Diets with high glycaemic index/load are associated with depressive symptoms; experimental exposure to high glycaemic load increases depressive symptoms in healthy volunteers with a moderately large effect.
  • Inflammation may link diet and depression: Mediterranean diets can reduce inflammation markers, high-calorie/saturated-fat meals stimulate immune activation, and anti-inflammatory agents can significantly reduce depressive symptoms.
  • Gut microbiome evidence is promising but not causal: probiotics can alter brain response to emotional attention tasks and may reduce depression symptoms, yet no causal relationship between specific microbes or metabolites and complex human emotions has been established.

Methods

  • Design: narrative/analysis article synthesizing existing evidence; no primary data collection or systematic review methods are described.
  • Evidence base: cites epidemiological, longitudinal, clinical experimental, observational, and randomized controlled trial findings on diet, glycaemia, inflammation, gut microbiome, and mental health.
  • Main analysis: conceptual synthesis of hypothesized pathways—glycaemia, immune activation, and gut-brain signalling—plus discussion of intervention evidence and research priorities.

Limitations

  • The paper states more research is needed to understand mechanisms and determine if, how, and when nutrition can improve mental health; causal roles of dietary inflammation are not established, and whether diet-induced microbiome changes affect depressive symptoms or clinical depressive disorders remains to be shown.
  • The paper notes reverse causality and barriers to healthy diets in people with mental illness; a recent large trial found no significant benefits of a Mediterranean-diet behavioural intervention for adults with subclinical depressive symptoms, while smaller trials in current depression showed moderately large improvements, and expectations may affect results.
  • Evident from the text: as a narrative review/analysis, it does not report a systematic search, risk-of-bias assessment, or meta-analysis, so conclusions rely on cited studies of varying designs.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1136/bmj.m2382

Cites

43 of 43 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 63 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    Relationships between nutrition and longstanding mental illness are compounded by barriers to maintaining a healthy diet.

    “In addition, relationships between nutrition and longstanding mental illness are compounded by barriers to maintaining a healthy diet.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] source

      Not checked in the free run.

  • Premisecitation

    Healthy eating patterns, such as the Mediterranean diet, are associated with better mental health than unhealthy eating patterns, such as the Western diet.

    “Healthy eating patterns, such as the Mediterranean diet, are associated with better mental health than “unhealthy” eating patterns, such as the Western diet”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] source

      Not checked in the free run.

  • Premisecitation

    Adherence to healthy or Mediterranean dietary patterns is associated with a reduced risk of depression.

    “epidemiological research has observed that adherence to healthy or Mediterranean dietary patterns—high consumption of fruits, vegetables, nuts, and legumes; moderate consumption of poultry, eggs, and dairy products; and only occasional consumption of red meat—is associated with a reduced risk of depression.3”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] source

      Not checked in the free run.

  • Interpretationreasoning

    There is clear potential for reverse causality between diet and mental health.

    “However, the nature of these relations is complicated by the clear potential for reverse causality between diet and mental health (fig 1).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Alterations in food choices or preferences in response to temporary psychological state are common human experiences.
    • Rests on an assumption: Mood itself can affect our food choices.
  • Interpretationnone given

    Poor nutrition may be a causal factor in the experience of low mood.

    “Poor nutrition may be a causal factor in the experience of low mood, and improving diet may help to protect not only the physical health but also the mental health of the population, say Joseph Firth and colleagues”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 6
  • May combine two claims. 7

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    The effects of certain foods or dietary patterns on glycaemia, immune activation, and the gut microbiome may play a role in the relationships between food and mood.

    “The effects of certain foods or dietary patterns on glycaemia, immune activation, and the gut microbiome may play a role in the relationships between food and mood”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Improving diet may help protect not only the physical health but also the mental health of the population.

    “Poor nutrition may be a causal factor in the experience of low mood, and improving diet may help to protect not only the physical health but also the mental health of the population, say Joseph Firth and colleagues”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Consumption of highly refined carbohydrates can increase the risk of obesity and diabetes.

    “Consumption of highly refined carbohydrates can increase the risk of obesity and diabetes.5”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    The inflammatory response to foods with a high glycaemic index raises the possibility that diets with a high glycaemic index are associated with symptoms of depression through the broader connections between mental health and immune activation.

    “Furthermore, the inflammatory response to foods with a high glycaemic index13 raises the possibility that diets with a high glycaemic index are associated with symptoms of depression through the broader connections between mental health and immune activation.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Stressors experienced the previous day, or a personal history of major depressive disorders, may cancel out the beneficial effects of healthy food choices on inflammation and mood.

    “For example, recent clinical research has observed that stressors experienced the previous day, or a personal history of major depressive disorders, may cancel out the beneficial effects of healthy food choices on inflammation and mood.22”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    The inflammatory effects of a diet high in calories and saturated fat have been proposed as one mechanism through which the Western diet may have detrimental effects on brain health, including cognitive decline, hippocampal dysfunction, and damage to the blood-brain barrier.

    “Indeed, the inflammatory effects of a diet high in calories and saturated fat have been proposed as one mechanism through which the Western diet may have detrimental effects on brain health, including cognitive decline, hippocampal dysfunction, and damage to the blood-brain barrier.15”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Anti-inflammatory interventions may only benefit certain people characterised by an inflammatory phenotype, or those with comorbid inflammatory conditions.

    “Furthermore, as heightened inflammation occurs in only some clinically depressed individuals, anti-inflammatory interventions may only benefit certain people characterised by an “inflammatory phenotype,” or those with comorbid inflammatory conditions.18”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning

    Whether changes to the gut microbiome induced by diet can affect depressive symptoms or clinical depressive disorders, and the time in which this could feasibly occur, remains to be shown.

    “Furthermore, whether changes to the gut microbiome induced by diet can affect depressive symptoms or clinical depressive disorders, and the time in which this could feasibly occur, remains to be shown.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Consumption of a diet high in fibres, polyphenols, and unsaturated fatty acids can promote gut microbial taxa which can metabolise these food sources into anti-inflammatory metabolites, such as short chain fatty acids, while lowering the production of secondary bile acids and p-cresol.

    “Conversely, the consumption of a diet high in fibres, polyphenols, and unsaturated fatty acids (as found in a Mediterranean diet) can promote gut microbial taxa which can metabolise these food sources into anti-inflammatory metabolites,15 28 such as short chain fatty acids, while lowering the production of secondary bile acids and p-cresol.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [15] source

      Not checked in the free run.

    • cites [28] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Later consequences of a poor diet include obesity and diabetes, which have already been shown to be associated with poorer mental health.

    “For example, the later consequences of a poor diet include obesity and diabetes, which have already been shown to be associated with poorer mental health.11 31 32 33”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [11] source

      Not checked in the free run.

    • cites [31] source

      Not checked in the free run.

    • cites [32] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    No causal relationship between specific microbes, or their metabolites, and complex human emotions has been established so far.

    “However, no causal relationship between specific microbes, or their metabolites, and complex human emotions has been established so far.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationreasoning

    Creating environments and developing measures that promote healthy, nutritious diets, while decreasing the consumption of highly processed and refined junk foods, may provide benefits beyond physical health, including improved psychological wellbeing.

    “This message supports the idea that creating environments and developing measures that promote healthy, nutritious diets, while decreasing the consumption of highly processed and refined “junk” foods may provide benefits even beyond the well known effects on physical health, including improved psychological wellbeing.”
    Quote in the paperNot a substantial claim
12 of 12

  • The paper relies on this without support.

    The causes of mental illness are many and varied, and they will often present and persist independently of nutrition and diet.

    “At the same time, it is important to be remember that the causes of mental illness are many and varied, and they will often present and persist independently of nutrition and diet.”

  • The paper relies on this without support.

    Stigmatisation about an individual’s dietary choices and mental health could itself be a causal pathway to increasing the risk of poorer mental health.

    “Indeed, such stigmatisation could be itself be a casual pathway to increasing the risk of poorer mental health.”

  • The paper relies on this without support.

    Alterations in food choices or preferences in response to temporary psychological state are common human experiences.

    “For example, alterations in food choices or preferences in response to our temporary psychological state—such as “comfort foods” in times of low mood, or changes in appetite from stress—are common human experiences.”

  • The paper relies on this without support.

    Mood itself can affect our food choices.

    “Although mood itself can affect our food choices”

  • The paper relies on this without support.

    The relationships between diet and mental health are complex and multidirectional.

    “While acknowledging the complex, multidirectional nature of the relationships between diet and mental health (fig 1), in this article we focus on the ways in which certain foods and dietary patterns could affect mental health.”
5 of 5

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Related

Authors
Firth, J., Gangwisch, J. E., Borsini, A., Wootton, R. E., & Mayer, E. A.
Affiliations
  • University of Manchester (GB)
  • New York State Psychiatric Institute (US)
  • King's College London (GB)
  • University Hospitals Bristol NHS Foundation Trust (GB)
  • University of California, Los Angeles (US)
Corresponding author
Firth, Joseph
ORCID
Venue
BMJ
Publisher
BMJ
Published
2020-06-29
Volume
369
Pages
m2382
ISSN
1756-1833 (ISSN-L)
DOI
10.1136/bmj.m2382
PMC
PMC7322666
OpenAlex
W3037973279
Cited by
475
References
42
Citations by year
2026: 65 · 2025: 113 · 2024: 101 · 2023: 77 · 2022: 64 · 2021: 48 · 2020: 6
FWCI
36.56
Type
journal article
Language
en
Update notices
correction (2020-11-09)
Open access
Licence
Locations
  • BMJ (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Research Explorer (The University of Manchester) (publishedVersion, other-oa)
  • HighWire Press Open Archive (submittedVersion)
  • Explore Bristol Research (submittedVersion, cc-by-nc)
Funders
  • U.S. Department of Defense
  • Danone
  • South London and Maudsley NHS Foundation Trust
  • University Hospitals Bristol NHS Foundation Trust
  • UK Research and Innovation
  • NIHR Biomedical Research Centre, Royal Marsden NHS Foundation Trust/Institute of Cancer Research
  • Axial Biotherapeutics
  • National Institute for Health and Care Research (NIHR-INF-0632)
  • King's College London
  • European Commission (HORIZON2020)
  • University of Bristol
  • Eisai
  • Medical Research Council
  • National Institute of Diabetes and Digestive and Kidney Diseases
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Nutritional Studies and Diet
  • Health Sciences › Nursing › Nutrition and Dietetics › Fatty Acid Research and Health
  • Health Sciences › Nursing › Nutrition and Dietetics › Nutrition, Health and Food Behavior
Keywords
diet, nutrition, psychological well-being, depressive mood, depression, mental health
MeSH terms
Gastrointestinal Microbiome, Diet, Healthy, Anxiety, Cognition, Depression, Humans, Inflammation, Nutritional Physiological Phenomena, Nutritional Status

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Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

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