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Abstract

Mental, neurological and substance-use disorders presently represent the greatest global burden of disease. Likewise, depression and other psychopathologies are elevated risk comorbidities of other health hazards, such as obesity. Nutrition has been implicated in behaviour, mood and in the pathology and treatment of mental illness. In this brief editorial, we aim to set the scale of the problem in context and overview advances and recent evidence linking nutrition to psychological outcomes. The purpose of the 2016 Nutrition Society Winter Meeting, ‘Diet, nutrition and mental health and wellbeing’ was to review where the evidence is strong, where there are unmet needs for research and to draw together the communities working in this area to share their findings. The papers presented demonstrated clear advancements that are being made in this field. The meeting illustrated compelling support for nutrition as a modifiable risk factor. The present research in the field and evidence presented at the 2016 Nutrition Society Winter Meeting lead us to postulate that even interventions with relatively modest effect sizes may plausibly and significantly curtail the disease burden of mental and neurological disease by food- and nutrient-based approaches.
Editorial
The role of diet and nutrition on mental health and wellbeing
Mental, neurological and substance-use disorders presently represent the greatest global bur-
den of disease. Likewise, depression and other psychopathologies are elevated risk
comorbidities of other health hazards, such as obesity. Nutrition has been implicated in
behaviour, mood and in the pathology and treatment of mental illness. In this brief editorial,
we aim to set the scale of the problem in context and overview advances and recent evidence
linking nutrition to psychological outcomes. The purpose of the 2016 Nutrition Society
Winter Meeting, Diet, nutrition and mental health and wellbeingwas to review where
the evidence is strong, where there are unmet needs for research and to draw together the
communities working in this area to share their ndings. The papers presented demonstrated
clear advancements that are being made in this eld. The meeting illustrated compelling sup-
port for nutrition as a modiable risk factor. The present research in the eld and evidence
presented at the 2016 Nutrition Society Winter Meeting lead us to postulate that even inter-
ventions with relatively modest effect sizes may plausibly and signicantly curtail the disease
burden of mental and neurological disease by food- and nutrient-based approaches.
Diet: Nutrition: Mental health: Cognition: Wellbeing
Mental, neurological and substance-use disorders are the
leading global burden of disease
It has recently been estimated that mental, neurological and
substance-use disorders (i.e. schizophrenia, depression, epi-
lepsy, dementia, alcohol dependence) account for 13 % of
the global burden of disease placing mental illness as the
greatest burden, exceeding both CVD and cancer
(1)
. While
sobering, these gures are perhaps unsurprising since there
is now one new case of dementia diagnosed every 4 s, or
7·7 million cases per year
(2)
. More than 300 million people
are now living with depression, an increase of more than
18 % between 2005 and 2015. By 2020, it is estimated that
between 15 and 30 million people will attempt suicide and
approximately 1·5 million per year will die by suicide each
year
(3)
. Alcohol and illicit drug use account for over 5·1%
of global burden of disease and worldwide, 3·3 million
deaths every year result from harmful use of alcohol
(4)
.
From social and economic perspectives, our health sys-
tems are not prepared for this extraordinary global bur-
den. Lobbying for legislative and community-level
interventions has begun and a World Health Assembly
resolution passed in May 2013 has called for a compre-
hensive, coordinated response to mental disorders at
country level. While treatment intervention is urgently
needed, health improvements and cost savings are achiev-
able by providing targeted, evidence-based, disease pre-
vention programmes that reduce modiable risk factors.
Diet and nutrition as preventative measures
Nutritional psychiatry is a new, rapidly emerging eld
of nutrition and mental health and is one such avenue
of prevention. Over the past decade, there has been a
steady increase in epidemiological studies investigating
the relationships between dietary patterns and mental
states. Both cross-sectional and longitudinal studies
have shown that the more one eats a Western or highly
processed diet, the more one is at risk for developing
psychiatric symptoms, such as depression and anxiety.
Conversely, the more one eats a Mediterranean-style
diet, the more one is protected from developing a men-
tal disorder
(5)
. In terms of direction of causality, in sev-
eral studies, the dietary pattern has been shown to
precede the onset of psychiatric symptoms. One rando-
mised controlled trial published this year in BMC
Medicine demonstrated quite striking effects of a
3-month dietary intervention on moderate-to-severe
depression, with a signicantly greater improvement in
the dietary intervention group and remission achieved
in 32 % of this group
(6)
.
The consequences of a poor diet also impact on a fur-
ther global health hazard: obesity. Alzheimers disease
and depression are comorbidities of obesity, leading to
the theory that vascular impairments may have a role
in the development of dementia and psychiatric patholo-
gies. As a result of these observations, Alzheimers dis-
ease and other dementias are now being thought of as
potentially preventable diseases. In a 27-year longitu-
dinal study, obesity in mid-life was shown to double
the risk of developing dementia at a later age
(7)
; more-
over while cognitive decits have been associated with
glycaemic regulation in diabetes, only in the recent
years has it been observed that cognitive decits exist
in young healthy, normal weight individuals with poor
glucoregulation, again exemplifying the need for early,
rather than later life, preventative nutrition measures.
Proceedings of the Nutrition Society (2017), 76, 425426 doi:10.1017/S0029665117001057
© The Authors 2017 First published online 14 July 2017
Proceedings of the Nutrition Society
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In addition to whole dietary and intervention strategies,
signicant advances have also been made in the study of
nutraceuticals. Previous research in this area has been
badged as complementary medicineand scientic rigor
of research investigating these interventions has not
always matched that of pharmaceutical research.
However, good converging evidence from high-quality
randomised controlled trials is now demonstrating effect-
iveness of a large number of nutraceuticals as mood-
modifying and cognitive-enhancing agents in both clinical
and healthy populations (a comprehensive review is
beyond the scope of the editorial). Recent mechanistic
work has indicated plausible, modiable, cognition-
related targets for nutraceuticals, including processes
involved with systemic and central vascular function,
inammation, metabolism, central activation, improved
neural efciency and angiogenesis. The quantity of good,
well-controlled clinical trials examining nutraceutical
interventions has meant that nutraceuticals are increas-
ingly being used and prescribed in psychiatric practice.
A further new avenue in nutritional psychiatry has
been the eruption of research targeting the modulation
of the gut microbiota (through probiotic and prebiotic
foods and supplements) as a novel therapy for the treat-
ment of various neuropsychiatric conditions. The bidirec-
tional communication between the gut microbiota and
the brain has been shown to inuence neurotransmission
and the behaviour that is often associated with neuro-
psychiatric conditions, and likewise the microbiome has
been associated with multiple systemic pathologies and
obesity
(8)
. However, this research is still in its infancy
with an urgent need for prospective studies.
The mechanisms of nutritional impact on the brain are
likely to be many, complex and compound. However,
recent research has focused on adult hippocampal neuro-
genesis. The hippocampus is a brain region associated
with learning, memory and mood and is one of two struc-
tures in the adult brain where neurogenesis persists. The
degree of neurogenesis in the hippocampus has been linked
directly to cognition and mood, thus modulation of hippo-
campal neurogenesis by diet has recently emerged as a pos-
sible mechanism by which nutrition may impact on brain
plasticity, function and mental health
(9)
.
Summary and nal thoughts
There have been some major advances in our understand-
ing of the impact of nutrition on brain function and the
aetiology and treatment of these disorders. Future break-
throughs are likely to combine nutritional genomics and
neuroscience with psychological and psychiatric research.
Due to the scale of the burden of mental, neurological and
substance-use disorders and the universality of food as a
modiable risk factor, even small improvements in the
nutritional environment may translate to large gains in
mental health and wellbeing at a population level.
Substantial research progress is being made in this eld
and the contemporary research outlining the evidence in
relation to whole dietary interventions, nutraceuticals,
alcohol use and putative mechanisms of action is
presented in the present issue of Proceedings of the
Nutritional Society in the form of a series of review papers
authored by the speakers of the 2016 Nutrition Society
Winter Meeting. However, future advancement is contin-
gent upon appropriate investment and concerted action by
mental health advocates, funding bodies, and policy
makers, and the inclusion and recognition of the role of
nutrition at the level of policymaking.
Lauren Owen
1
* and Bernard Corfe
2,3
1
Department of Psychology, University of Central
Lancashire, Darwin Building, Fylde Rd, Preston PR1
2HE, UK
2
Molecular Gastroenterology Research Group, Academic
Unit of Surgical Oncology, Department of Oncology &
Metabolism, The Medical School, Beech Hill Road,
Shefeld, S10 2RX, UK
3
Insigneo Institute for In Silico Medicine, The University
of Shefeld, UK
*Corresponding author: L. Owen,
email Dr.lauren.owen@gmail.com
Acknowledgments
None.
Financial Support
None.
Conicts of Interest
None.
Authorship
None.
References
1. Vigo D, Thornicroft G & Atun R. Estimating the true global
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2. World Health Organization (2012) Dementia: a Public
Health Priority. World Health Organization.
3. Bertolote JM & Fleischmann A (2002) A global perspective
in the epidemiology of suicide. Suicidology 7,68.
4. World Health Organization (2014) Global Status Report on
Alcohol and Health 2014. World Health Organization.
5. Jacka FN, Mykletun A & Berk M (2012) Moving towards a
population health approach to the primary prevention of
common mental disorders. BMC Med 10, 149.
6. Jacka FN, ONeil A, Opie R et al. (2017) A randomised con-
trolled trial of dietary improvement for adults with major
depression (the SMILEStrial). BMC Med 15, 23.
7. Whitmer RA, Gunderson EP, Barrett-Connor E et al. (2005)
Obesity in middle age and future risk of dementia: a 27 year
longitudinal population based study. BMJ 330, 1360.
8. CardingS, Verbeke K, VipondDT et al. (2015) Dysbiosis of the
gut microbiota in disease. Microbial Ecol Health Dis 26,26191.
9. Stangl D & Thuret S (2009) Impact of diet on adult hippo-
campal neurogenesis. Genes Nutr 4, 271282.
Editorial426
Proceedings of the Nutrition Society
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There is a need for the development of effective universal preventive approaches to the common mental disorders, depression and anxiety, at a population level. Poor diet, physical inactivity and smoking have long been recognized as key contributors to the high prevalence noncommunicable diseases. However, there are now an increasing number of studies suggesting that the same modifiable lifestyle behaviors are also risk factors for common mental disorders. In this paper we point to the emerging data regarding lifestyle risk factors for common mental disorders, with a particular focus on and critique of the newest evidence regarding diet quality. On the basis of this most recent evidence, we consequently argue for the inclusion of depression and anxiety in the ranks of the high prevalence noncommunicable diseases influenced by habitual lifestyle practices. We believe that it is both feasible and timely to begin to develop effective, sustainable, population-level prevention initiatives for the common mental illnesses that build on the established and developing approaches to the noncommunicable somatic diseases.<br /
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We argue that the global burden of mental illness is underestimated and examine the reasons for under-estimation to identify five main causes: overlap between psychiatric and neurological disorders; the grouping of suicide and self-harm as a separate category; conflation of all chronic pain syndromes with musculoskeletal disorders; exclusion of personality disorders from disease burden calculations; and inadequate consideration of the contribution of severe mental illness to mortality from associated causes. Using published data, we estimate the disease burden for mental illness to show that the global burden of mental illness accounts for 32·4% of years lived with disability (YLDs) and 13·0% of disability-adjusted life-years (DALYs), instead of the earlier estimates suggesting 21·2% of YLDs and 7·1% of DALYs. Currently used approaches underestimate the burden of mental illness by more than a third. Our estimates place mental illness a distant first in global burden of disease in terms of YLDs, and level with cardiovascular and circulatory diseases in terms of DALYs. The unacceptable apathy of governments and funders of global health must be overcome to mitigate the human, social, and economic costs of mental illness.
Dementia: a Public Health Priority. World Health Organization
World Health Organization (2012) Dementia: a Public Health Priority. World Health Organization.