SEARCH

SEARCH BY CITATION

Keywords:

  • Diet;
  • depression;
  • ADHD;
  • omega 3;
  • autism;
  • conduct disorder

Abstract

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

The role played by diet in mental health is of increasing interest to patients, parents, health professionals and public policy makers. This review examines the literature assessing the role of diet in childhood cognitive development, school performance and behaviour. The effects of inadequate dietary intake and of nutrient supplements are considered. Studies of diet and specific psychiatric diagnoses such as depression and psychosis are discussed, with a focus on the evidence for the child and adolescent population.


Key Practitioner Message:

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.
  • • 
    Children need a nutritionally balanced diet for both their mental and physical development
  • • 
    Use of dietary supplements such as micronutrients or omega 3 fatty acids is a popular practice for ADHD although there is only limited supporting evidence
  • • 
    Dietary supplements (in particular the omega 3 fatty acid EPA) may have a therapeutic role in depression although most research has been conducted in adults with depression rather than in children or adolescents
  • • 
    Some food additives can worsen hyperactivity

Introduction

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

There is an established connection between dietary intake and physical health. There are immediate effects such as weight changes, and longer term implications of a poor diet which have been linked to, amongst other illnesses, cardiovascular disease, diabetes and cancer.

The causes of mental illness will usually be multifactorial. Increasing evidence suggests that dietary intake may be a significant contributory factor to mental health (Van de Weyer, 2005). This review will examine some of the research evidence of the possible effects of nutritional intake upon childhood neurocognitive development, behaviour and specific psychiatric disorders.

Required components of a normal diet are listed in Box 1. The UK Food Standards Agency introduced the ‘Balance of Good Health’ food plate model (Department of Health, 1991), recently updated to the ‘EatWell Plate’ (Food Standards Agency, 2007a), a visual tool which advises the proportions of the main food types to achieve a balanced diet. These include starchy carbohydrate foods, fruit and vegetables, protein-rich foods such as meat and pulses and dairy products.

Early life nutrition and neurocognitive development

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

Poor maternal nutrition affects fetal growth (Godfrey et al., 1997) and may lead to premature birth (Bloomfield et al., 2003). Aylward et al. (1989) demonstrated lower IQ and poorer language and reading skills in children who were low birth weight babies. The primary causes of low birth weight are prematurity and intrauterine growth restriction which may occur together, especially in the very low birth weight babies. Cognitive impairments which result from complications of prematurity (e.g. infection, intraventricular haemorrhage, poor feeding) may be difficult to differentiate from those associated with growth restriction (e.g. poor maternal nutrition, developmental abnormalities in the infant).

Hibbeln et al. (2007) demonstrated that high maternal fish intake (and therefore higher essential fatty acid intake, as oily fish are the main dietary source of such fatty acids) was associated with higher verbal IQ at 7 years in the child. Maternal iodine is important to in utero development, not only to the prevention of fetal thyroid deficiency but also to the prevention of less severe cognitive deficits (Grantham-McGregor, Fernald & Sethuraman, 1999).

There is evidence for improved cognitive abilities in breast fed infants (Anderson, Johnstone & Remley, 1999). This may be due in part to high levels of essential fatty acids in breast milk, as well as to the presence of maternal immunoglobulins. Genes may moderate the effects of inter-individual variations in diet on intellectual development. Caspi et al. (2007) demonstrated that breastfeeding conferred a higher IQ only in individuals carrying a variant of FADS2, a gene controlling fatty acid metabolism. This study of two independent birth cohorts excluded alternative explanations for IQ variation, such as social class, the effect of genetics on the decision to breastfeed, and maternal cognitive ability. The study provides evidence of gene-environment interaction contributing to the effect of diet on cognitive abilities and mental health. It is likely that other such interactions exist, and future epidemiological research should investigate the role of genetics, diet and the interaction between them.

Food intake replacing milk needs to contain macro and micronutrients which are age appropriate, but there is as yet little evidence of benefit from supplementing the normal requirements. Formula milk supplemented with polyunsaturated fatty acids was given to infants up to 12 months of age (Auestad et al., 2003) but a control group fed normal formula milk showed similar cognitive, visual and language development at 39 months.

Poor nutrition can lead to slowed body growth and effects on cognitive and behavioural development which are both immediate and long term (Meeks-Gardner & Grantham-McGregor, 1994). There may be some reversibility of cognitive deficits where previously malnourished infants are given macronutrient and micronutrient supplementation for catch-up growth at a sufficiently early time in infancy (Bellisle, 2004).

School performance and behaviour

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

Both long-term malnutrition and temporarily insufficient food intake may cause problems at school resulting in poor concentration and lethargy. Breakfast clubs in schools have received publicity and have been reported to improve concentration and learning outcomes amongst pupils (Papamandjaris, 2000). Numerous studies (Wesnes et al., 2003; Benton & Jarvis, 2007; Ingwersen et al., 2007) suggest that school academic performance can be improved by ensuring that children do not miss breakfast. Behaviour as well as academic achievement has been improved in studies providing timely food (Murphy et al., 1998).

Making appropriate food available may not be enough, however. Avoidance of new foods (food neophobia) in children has an adverse effect on food choices, particularly of fruit, vegetables and protein rich foods. Cooke, Haworth and Wardle (2007) surveyed the eating habits of 5390 pairs of twins aged 8–11 years and concluded that neophobia appears to be a highly heritable trait. However exposure-based interventions such as offering repeated tasting of a disliked food (Wardle et al., 2003) or pairing neutral flavours with preferred flavours to elicit conditioned responses (Havermans & Jansen, 2007) may reduce aversion to specific foods.

Iron deficiency anaemia has been linked to impairment in cognitive function in schoolchildren (Sungthong, Mo-Suwan & Chongsuvivatwong, 2002; Agaoglu et al., 2007). Iron deficiency is significantly prevalent worldwide and using anaemia as an indirect indicator, the World Health Organisation has estimated that most preschool children and pregnant women in non industrialised countries, and 30–40% in industrialised countries, are iron deficient (WHO, 2001).

It is important not to forget water as an essential part of diet, especially in children. Even mild dehydration can cause restlessness, irritability and loss of concentration (Bar-David, Urkin & Kosminsky, 2005).

Behavioural problems and attention deficit hyperactivity disorder

ADHD is estimated to be found in 5–10% of the school age population [345,000–690,000 in England (Taylor et al., 1991)]. Poor concentration affects learning, and the symptoms of ADHD increase the risk of disruptive behaviour, interfering with learning in children with ADHD and in their classmates.

Studies selecting children with formal ADHD diagnoses are outnumbered by studies examining more general behavioural problems, which may be termed hyperactivity. Extrapolating the findings of the latter studies to children with ADHD needs to be done with caution.

Food additives.  In the 1970s, allergist Benjamin Feingold in San Francisco claimed a ‘30–50% benefit’ in young patients with hyperactivity eating a diet free from certain artificial flavourings and colourings (Feingold, 1975). Controlled trials are now supporting these anecdotal findings. A meta-analysis (Schab & Trinh, 2004) examined 15 placebo controlled trials addressing the effects of artificial food colourings on the behaviour of hyperactive children (average age across the studies 7.9 years, some with formal ADHD diagnoses). This found that artificial food colourings promoted hyperactivity in hyperactive children.

Two more recent studies examined community based samples of children, rather than clinical samples. The first study (Bateman et al., 2004) concluded an adverse effect of food colourings and preservatives on the behaviour of 3 year olds, an effect not influenced by the presence or absence of prior hyperactivity. The second (McCann et al., 2007) found that that the addition of food additives to the diet of both 3 year olds and 8/9 year olds selected from the general population led to increased hyperactivity.

Studies of exclusion diets, where children only eat a limited range of ‘natural’ foods have suggested that such diets may reduce symptoms of hyperactivity. A recent randomised controlled trial of children with ADHD (mean age 6.2 years) given a supervised elimination diet demonstrated improvement in behavioural symptoms in 70% of children. (Pelsser et al., in press). The study was small, however, involving only 27 children and it was clearly not possible for families to be unaware that their children were in the ‘exclusion diet’ group.

Other researchers have examined the effects of restrictive ‘oligoantigenic’ diets (Egger et al., 1985; Schmidt et al., 1997) or ‘few foods’ diets (Carter et al., 1993). The studies have systematically reintroduced excluded foods after a period of limited diet. The aim is to identify items in the diet which provoke behavioural problems, and the studies suggested that some children will benefit from individually tailored diets eliminating some foods or additives. This study noted that it is not just artificial additives that can lead to behavioural problems.

The Food Standards Agency has produced guidelines recommending that eliminating certain artificial food colours and the preservative sodium benzoate may reduce hyperactivity (Food Standards Agency, 2007b). By contrast, the most recent draft of the UK National Institute for Health and Clinical Excellence guidelines on ADHD management (NICE, 2008) specifically state that ‘eliminating artificial colouring and additives from the diet is not recommended as a generally applicable treatment for ADHD’. The guidelines recommend referral to a dietitian where food or drink appears to affect behaviour, and ‘further management (such as elimination of specific foods) should be jointly undertaken by the dietitian, mental health specialist or paediatrician and the family’.

Sugar in the diet has been linked anecdotally to childhood hyperactivity, particularly by parents. Induced hypoglycaemia in non diabetic adults (McAuley et al., 2001) was found to cause attentional dysfunction without altering non verbal intelligence. An abrupt fall in blood sugar levels following an insulin surge responding to sugar consumption may in theory replicate this effect. However a meta-analysis of 16 studies (Wolraich, Wilson & White, 1995) examining the effects of sugar on behaviour or cognition in children concluded that there was no clear evidence of either being significantly affected by sugar intake.

Essential fatty acids.  Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fatty acids found in small quantities in the normal human diet and are known as omega 3 fatty acids. They are precursors to brain hormones which function in the release of some neurotransmitters and are important for neuronal membrane flexibility. The human body can convert another fatty acid found in a wider range of foods, alpha-linolenic acid (ALA), to EPA and DHA. This conversion process is inhibited by the presence of saturated fats (present in high quantities in processed food). It is also inhibited by reduced dietary co-factors (including zinc, magnesium, manganese, vitamins A, B3 and B6), alcohol, smoking and diabetes. Diets favouring processed foods, which are high in saturated fats and low in micronutrients, may lead to low EPA and DHA levels. Low dietary levels of fatty acids can be increased by dietary supplements containing omega 3 fatty acids (EPA, DHA) or by eating oily fish, the main dietary source of EPA (Richardson, 2006).

Colquhoun and Bunday (1981) observed that children who were hyperactive (although not necessarily diagnosed with ADHD) had similar clinical symptoms to children with essential fatty acid (EFA) deficiency (excessive thirst and urination, dry skin or eczema and asthma). Mitchell et al. (1987) found that some children with ADHD did have significantly lower serum fatty acid concentrations than control subjects and hypothesised that a subgroup of children with ADHD may have altered fatty acid metabolism, as their dietary intake was not necessarily lower than that found with control subjects.

Recent theory (Hallahan & Garland, 2004) suggests an inverse relationship between plasma omega 3 levels and behavioural disturbance in impulsivity disorders, which includes ADHD. Colter, Cutler and Meckling (2008) studied 11 adolescents with ADHD with an age matched control group, and found the ADHD group to have lower blood levels of DHA than controls, despite equivalent dietary intake. The authors suggest that there may be differences in fatty acid metabolism between the two groups irrespective of diet, a possibility which warrants further research.

Supplementation studies show mixed results (Hallahan & Garland, 2004). A study of 8–12 year olds with ‘ADHD related symptoms’ (Richardson & Puri, 2002) claimed better results using EPA with DHA in supplements given for 12 weeks. The participants, selected from a school for children with literacy problems, did not have formal ADHD diagnoses.

The UK Oxford–Durham Study (Richardson & Montgomery, 2005) gave essential fatty acid supplements [EPA, DHA and GLA (Gamma-linolenic acid, an omega 6 fatty acid)] to children with developmental co-ordination disorder (DCD) as reported by their teachers. There were no significant treatment effects on motor skills. As a secondary finding the group receiving dietary supplements showed statistically significant improvements in hyperactivity symptoms and in reading and spelling abilities compared to the placebo group. Formal ADHD diagnostic assessments were not carried out, although hyperactivity levels were high at baseline; nor were children assessed for baseline deficiency of fatty acids.

Stevens et al. (2003) gave fatty acid supplements (predominantly DHA) to children with behaviour associated with ADHD. The results did not show clear improvement in their behaviour. In another study (Hirayama, Hamazaki & Terasawa, 2004) some of the children did have a diagnosis of ADHD, but again DHA did not improve ADHD related symptoms, a conclusion shared by earlier researchers (Voight et al., 2001). Sinn and Bryan (2007) saw some improvement in parent rating scales of behaviour when 7–12 year olds with behavioural problems received fatty acid supplements, but teacher rating scales were unaffected. A more recent study (Sinn, Bryan & Wilson, 2008) of 8–12 year old children with ADHD described some improvement in attention with polyunsaturated fatty acid supplementation but micronutrients (multivitamins/minerals) were taken in addition to the fatty acids. The results obtained from these studies cannot provide unequivocal evidence of the effectiveness of fatty acid supplementation in ADHD.

Itomura et al. (2005) gave fish oil (predominantly DHA) to 9–12 year old children with physical aggression and impulsivity, without clear evidence of benefit.

The omega 3 supplements used in the above trials led to few reported adverse effects. Some have been reported elsewhere, such as decreased glucose tolerance, diarrhoea, abdominal pain, bloating, nausea, flatulence, fatigue, somnolence, thrombocytopenia, skin irritation, vitamin toxicity and oxidative damage in large doses (Radia, 2005). There have been concerns about the heavy metal content of fish oils, particularly of mercury which is known to have potentially neurotoxic effects. This is a particular problem with fish caught close to shore, so fish oil obtained from ocean fish is recommended where used.

A topic barely covered by research to date is whether fatty acid supplementation leads to effects upon the behaviour and educational performance of school aged children who do not have preexisting behavioural or attentional problems.

Micronutrients.  There is a theory that some patients with ADHD are zinc deficient (Toren et al., 1996), and several trials have tested zinc supplementation. Two double blind placebo controlled trials have claimed improvement in symptoms of ADHD, one as a supplement alone (Bilici et al., 2004) and one alongside medication (Akhondzadeh, Mohammadi & Khademi, 2004).

There is some evidence for iron deficiency being associated with ADHD (Konofal et al., 2004) and beneficial results have been claimed for iron supplements but with inconsistent results in trials (Sever et al., 1997).

Behaviour disorders in adults. Gesch, et al. (2002) randomised young adult prisoners to supplements including minerals, vitamins and essential fatty acids or placebo. There was a significantly greater reduction in disciplinary offences in the supplement group. Lower dietary intake and lower blood levels of omega 3 are associated with aggression (Hallahan & Garland, 2004) and DHA supplementation was demonstrated to reduce aggression in a study of young adults (Hamazaki et al., 1996).

Pervasive developmental disorder

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

A number of theories currently focus on diet in an attempt to explain an apparent increase in diagnoses of autistic spectrum disorders over the past 20 years. Richardson and Ross (2000) cite features common to ADHD, dyslexia, dyspraxia and autism as suggestive of a common causality – in this case abnormalities of fatty acid availability. A postulated link between increased use of trans-fats in processed food and increased incidence of autism has raised popular interest, particularly via internet sites, but published studies are absent. With the emergence of gluten and casein free diets as possible treatment for autism, a Cochrane review (Millward et al., 2004) attempted to determine the efficacy of such diets on behaviour, cognitive and social functioning in individuals with autism. It was not possible to complete a meta-analysis as only one small randomised controlled trial was found (Kvinsberg et al., 2002). In this study 10 children were allocated to each of two groups (gluten and casein free diet or control). Assessments of development before and at one year claim improved development for the diet group. More good quality studies are needed in this field.

Psychiatric illnesses

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

Depression

The great majority of research into diet and depression has taken place in the adult rather than in the child or adolescent population. It cannot be presumed that the findings from adult studies are necessarily applicable to children.

Patton et al. (2004) demonstrated that prematurity and low birth weight are associated with higher rates of depression in adolescence. Poor maternal nutrition may contribute to both prematurity and low birth weight, although direct causation with subsequent adolescent depression is not proven.

Omega 3 fatty acids.  Low levels of fish consumption are associated with higher rates of depression at the national (Hibbeln, 1998) and individual level (Tanskanen et al., 2001). Depressed adults have lower red blood cell membrane concentrations of omega 3 fatty acids than controls, even when there is no difference in total calorie intake; and dietary intake of omega 3 fatty acids is negatively correlated with severity of depression (Edwards et al., 1998; Peet et al., 1998).

Randomised controlled trials have demonstrated that omega 3 supplements are more effective than placebo in the treatment of unipolar depression. EPA supplements have been shown to be superior to placebo in depressed adults, when given alongside existing treatment (Nemets, Stahl & Belmaker, 2002; Peet & Horrobin, 2002; Su et al., 2003). Combined EPA and DHA supplements were more effective than placebo in depressed children (age 6–12 years) (Nemets et al., 2006). This latter study notably used omega 3 as a monotherapy rather than as an augmenting agent to antidepressants. Combined EPA and DHA supplements caused a greater reduction in depressive symptoms and suicidality than placebo in adults who had presented with self-harm (Hallahan et al., 2007). This may contrast with SSRIs, which have been shown to cause greater self-harm related events than placebo in depressed children and adolescents (Dubicka, Hadley & Roberts, 2006). It is possible that only the EPA component of the supplement is beneficial, as studies (Marangell et al., 2003; Silvers et al., 2005) have not demonstrated improvement in adult depression where DHA is primarily used. A recent study (Jazayeri et al., 2008) of adults with major depressive disorder found equal therapeutic effects of EPA and fluoxetine on depressive symptoms and superior results from combined treatment over an eight week trial.

Only one of the above studies was carried out in children (and none in adolescents) so great caution should be exercised in extrapolating their findings to the adolescent population. However these studies do suggest that it is worthwhile to research omega 3 fatty acids supplementation in depressed children and adolescents.

Neurotransmitters and their precursors.  Dietary deficiency of tryptophan can reduce brain serotonin (Wurtman, Hefti & Melamed, 1980). A diet with no tryptophan but high in other amino acids acutely reduces brain tryptophan levels. This has been shown to induce depressive symptoms in adults who have recovered from depression (Smith, Fairburn & Cowen, 1997), but to have no effect on depressive symptoms in people without a history of depression (Gallagher et al., 2003).

Van Praag and Lemus (1986) demonstrated that L-trpytophan plus antidepressants was more effective than antidepressant alone in adults. However, reports of eosinophilia have led to tight restrictions on L-tryptophan use.

Micronutrients.  Folate deficiency is observed in depressed patients (although appetite change may contribute to this). A systematic review (Taylor et al., 2003) examined three randomised trials of folate use in depressed patients – in two trials alongside antidepressant treatment and in the third in comparison to trazodone. There were no significant differences and the review concluded that evidence for folate use in depression was ‘limited’.

Vitamin and mineral deficiencies, especially zinc, are found in depressed patients but there has been limited research into supplementing adult diets with zinc (Nowak et al., 2003) and chromium (Davidson et al., 2003).

A systematic review of the use of vitamin B6 (Williams et al., 2005) found that there was evidence for use of B6 in depression in pre-menopausal women, although did not conclude that it was useful in other depressed patients. As the above authors have noted, ‘the traditional role of B vitamins in mental health was limited to the recognition of the manifestation of psychiatric syndromes in [B vitamin] deficiencies, and their replacement’. There is a need to research further the use of micronutrients as specific supplements where adults and children have mental health diagnoses but do not necessarily have nutrient deficiencies. There is potential for dietary improvement and specific supplementation (Bamber, Stokes & Stephen, 2007) to provide an acceptable adjunct to standard treatment for depression.

It should be remembered, however, that dietary supplementation cannot necessarily be regarded as risk free. A recent Cochrane review (Bjelakovic et al., 2008) found no evidence that antioxidant supplements were effective in primary or secondary prevention in a variety of physical illnesses, and that some supplements (e.g. vitamins A and E) may even increase mortality. Indeed vitamin A, once regarded as a ‘safe’ supplement, can cause liver toxicity when taken in high quantities or by vulnerable individuals (Hathcock et al., 1990). It must be considered possible that any ‘natural’ food supplement can be toxic taken in high doses, or for long periods, or even as an idiosyncratic response.

Psychosis

Research has tended to concentrate on schizophrenia and, as with depression, most research has been within the adult population.

Epidemiological studies have identified a clear link between general nutritional deficiency in mothers and the later development of schizophrenia in their children (St Clair et al., 2005).

Fatty acids.  Hypotheses of causation have arisen from an observation that people with schizophrenia have lower levels of fatty acids. The ‘membrane hypothesis’ proposes that abnormal phospholipid metabolism may be present in adults with schizophrenia (Horrobin, Glen & Vaddadi, 1994), whilst other research (Peet et al., 2004) favours as yet unspecified abnormalities of fatty acid metabolism. A systematic review of treatment trials using omega 3 in schizophrenia (Joy, Mumby-Croft & Joy, 2006) concluded that all currently published studies were too small to be conclusive.

With the lack of evidence that dietary intervention improves psychosis in adults, such dietary intervention cannot be recommended as treatment for adolescents with psychosis.

Conclusions: The best diet for mental health?

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

Nutritional intake is essential for growth and optimal functioning. Children and young people need both an adequate quantity of food and nutritional balance in their daily diet. Food made from a wide variety of whole, unprocessed ingredients is likely to fulfill these requirements better than a diet relying upon heavily processed foods.

It is much less clear that taking dietary supplements in excess of normal daily requirements can prevent or treat mental health problems. Current evidence for the use of supplementary micronutrients and omega 3 fatty acids for the treatment of ADHD is weak. Some food additives do appear to worsen hyperactivity symptoms and behaviour in all children, including those with ADHD. It is also likely that some individual children respond adversely to particular foods such as sugar, although there may not be evidence that the population as a whole is affected. Parents who exclude dietary additives or foods on the basis of observation of their child’s behaviour should be supported, provided that their child’s diet remains nutritionally balanced.

Some evidence supports the use of micronutrient supplements, especially EPA as a monotherapy or as a supplement to antidepressants in depression. However most of the research has been conducted in adults rather than in children and adolescents. Much more information of optimum doses and side-effects is needed in the paediatric population before these can be recommended as standard treatments for children and young people.

Research evidence of the effects of diet and dietary change in autistic spectrum disorders, and in psychosis in young people is currently too sparse to offer recommendations for treatment.

Prospective studies are required for a better understanding of the longitudinal relationship between diet and specific mental health disorders. We will also need to know much more about the safety of prescribing long term micronutrient supplements such as omega 3 fatty acids for any condition, when the doses exceed those currently recommended in a balanced diet.

References

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.
  • Agaoglu, L., Torun, O., Unuvar, E., Sefil, Y., & Demir, D. (2007). Effects of iron deficiency anaemia on cognitive function in children. Arzneimittelforschung, 57, 426430.
  • Akhondzadeh, S., Mohammadi, M.R., & Khademi, M. (2004). Zinc sulfate as an adjunct to methylphenidate for the treatment of attention deficit disorder in children: A double blind and randomized trial. BMC Psychiatry, 4, 9.
  • Anderson, J.W., Johnstone, B.M., & Remley, D.T. (1999). Breast feeding and cognitive development: A meta- analysis. American Journal of Clinical Nutrition, 70, 525535.
  • Auestad, N., Scott, D.T., Janowsky, J.S., Jacobsen, C., Carroll, R.E., Montalto, M.B., Halter, R., Qiu, W., Jacobs, J.R., Connor, W.E., Connor, S.L., Taylor, J.A., Neuringer, K., Fitzgerald, K.M., & Hall, R.T. (2003). Visual, cognitive and language assessments at 39 months: A follow-up study of children fed formulas containing long chain polyunsaturated fatty acids to 1 year of age. Pediatrics, 112, 177183.
  • Aylward, G.P., Pfeiffer, S.I., Wright, A., & Verhulst, S.J. (1989). Outcome studies of low birth weight infants published in the last decade: a meta- analysis. Journal of Pediatrics, 115, 515520.
  • Bamber, D.J., Stokes, C.S., & Stephen, A.M. (2007). The role of diet in the prevention and management of adolescent depression. British Nutrition Foundation Nutrition Bulletin, 32, 9099.
  • Bar-David, Y., Urkin, J., & Kosminsky, E. (2005). The effect of voluntary dehydration on cognitive functions of elementary school children. Acta Paediatrica, 94, 16671673.
  • Bateman, B., Warner, J.O., Hutchinson, E., Dean, T., Rowlandson, P., Gant, C., Grundy, J., Fitzgerald, C., & Stevenson, J. (2004). The effect of a double blind placebo controlled artificial food colourings and benzoate preservative challenge on hyperactivity in a general population sample of preschool children. Archives of Diseases of Childhood, 89, 506511.
  • Bellisle, F. (2004). Effects of diet on behaviour and cognition in children. British Journal of Nutrition, 92 (Supplement 2), S227232.
  • Benton, D., & Jarvis, M. (2007). The role of breakfast and a midmorning snack on the ability of children to concentrate at school. Physiology and Behaviour, 90, 282385.
  • Bilici, M., Yildirim, F., Kandil, S., Bekaroglu, M., Yildirmis, S., Deger, O., Ulgen, M., Yildiran, A., & Aksu, H. (2004). Double blind placebo controlled study of zinc sulfate in the treatment of ADHD. Progress in Neuro-psychopharmacology and Biological Psychiatry, 28, 181190.
  • Bjelakovic, G., Nikolova, D., Gluud, L.L., Simonetti, R.G., & Gluud, C. (2008). Antioxidant supplements for the prevention of mortality in healthy participants and patients with various diseases. Cochrane Database of Systematic Reviews 2008, Issue 2, Art no.CD007176. DOI: DOI: 10 1002/14651858.CD007176.
  • Bloomfield, F.H., Oliver, M.H., Hawkins, P., Campbell, M., Phillips, D.J., Gluckman, P.D., Challis, J.R.G., & Harding, J.E. (2003). A periconceptional nutritional origin for non infectious preterm birth. Science, 300, 606.
  • Carter, C.M., Urbanowicz, M., Hemsley, R., Mantilla, L., Strobel, S., Graham, P.J., & Taylor, E. (1993). Effects of a few food diet in attention deficit disorder. Archives of Disease in Childhood, 69, 564568.
  • Caspi, A., Williams, B., Kim-Cohen, J., Craig, I.W., Milne, B.J., Poulton, R., Schalwyck, L.C., Taylor, A., Werts, H., & Moffitt, T.E. (2007). Moderation of breastfeeding effects on the IQ by genetic variation in fatty acid metabolism. Proceedings of the National Academy of Sciences, 104, 1886018865.
  • Colquhoun, I., & Bunday, S. (1981). A lack of essential fatty acids as a possible cause of hyperactivity in children. Medical Hypotheses, 7, 673679.
  • Colter, A.L., Cutler, C., & Meckling, K.A. (2008). Fatty acid status and behavioural symptoms of attention deficit hyperactivity disorder in adolescents: a case-control study. Nutrition Journal, 7, 8.
  • Cooke, L.J., Howarth, C.M.A., & Wardle, J. (2007). Genetic and environmental influences on children’s food neophobia. American Journal of Clinical Nutrition, 86, 428433.
  • Davidson, J.R., Abraham, K., Connor, K.M., & MacLeod, M.N. (2003). Effectiveness of chromium in atypical depression: A placebo controlled trial. Biological Psychiatry, 53, 261264.
  • Department of Health (1991). Dietary reference values for food energy and nutrients for the United Kingdom. Report on Health and Social Subjects 41. London: HMSO.
  • Dubicka, B., Hadley, S., & Roberts, C. (2006). Suicidal behaviour in youths with depression treated with new-generation antidepressants: Meta-analysis. British Journal of Psychiatry, 189, 393398.
  • Edwards, R., Peet, M., Shay, J., & Horrobin, D. (1998). Omega-3 polyunsaturated fatty acid levels in the diet and in red blood cell membranes of depressed patients. Journal of Affective Disorders, 48, 149155.
  • Egger, J., Carter, C.M., Graham, P.J., Gumley, D., & Soothill, J.F. (1985). Controlled trial of oligoantigenic treatment in the hyperkinetic syndrome. Lancet, 1, 540545.
  • Feingold, B.F. (1975). Hyperkinesis and learning disabilities linked to artificial foods flavors and colors. American Journal of Nursing., 75, 797803.
  • Food Standards Agency (2007a). The EatWell Plate. http://www.food.gov.uk/multimedia/pdfs/publication/eatwellplate0907.pdf, accessed 10th October 2008.
  • Food Standards Agency (2007b). Food Standards Agency issues revised advice on certain artificial colours. http://www.food.gov.uk/news/pressreleases/2007/sep/colours. Accessed 18 Oct 2007.
  • Gallagher, P., Massey, A.E., Young, A.H., & McAllister-Williams, R.H. (2003). Effects of acute tryptophan depletion on executive function in healthy male volunteers. BMC Psychiatry, 3, 10.
  • Gesch, B., Hammond, S.M., Hampson, S.E., Eves, A., & Crowder, M.J. (2002). Influence of supplementary vitamins, minerals and essential fatty acids on the antisocial behaviour of young adult prisoners. Randomized placebo controlled trial. British Journal of Psychiatry, 181, 2228.
  • Godfrey, K.M., Barker, D.J., Robinson, S., & Osmond, C. (1997). Maternal birthweight and diet in pregnancy in relation to the infant’s thinness at birth. British Journal of Obstetrics and Gynaecology, 104, 663667.
  • Grantham-McGregor, S., Fernald, L.C., & Sethuraman, K. (1999). Effects of health and nutrition on cognitive and behavioural development in children in the first three years of life. Food and Nutrition Bulletin, 20, 5399.
  • Hallahan, B., & Garland, M.R. (2004). Essential fatty acids and their role in the treatment of impulsivity disorders. Prostaglandins, Leukotrienes and Essential Fatty Acids, 71, 211216.
  • Hallahan, B., Hibbeln, J.R., Davis, J.M., & Garland, M.R. (2007). Omega-3 fatty acid supplementation in patients with recurrent self-harm: Single-centre double-blind randomised controlled trial. British Journal of Psychiatry, 190, 118122.
  • Hamazaki, T., Sawazaki, S., Itomura, M., Asaoka, E., Nagao, Y., Nishimura, N., Yazawa, K., Kuwamori, T., & Kobayashi, M. (1996). The effect of docosahexanoic acid on aggression in young adults. A placebo controlled double blind study. Journal of Clinical Investigation, 97, 11291134.
  • Hathcock, J.N., Hattan, D.G., Jenkins, M.Y., McDonald, J.T., Sundaresan, P.R., & Wilkening, V.L. (1990). Evaluation of vitamin A toxicity. American Journal of Clinical Nutrition, 52, 183202.
  • Havermans, R.C., & Jansen, A. (2007). Increasing children’s liking of vegetables through flavour-flavour learning. Appetite, 48, 259262.
  • Hibbeln, J.R. (1998). Fish consumption and major depression. Lancet, 351, 1213.
  • Hibbeln, J.R., Davis, J.M., Steer, C., Emmett, P., Rogers, I., Williams, C., & Golding, J. (2007). Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): An observational cohort study. Lancet, 369, 578585.
  • Hirayama, S., Hamazaki, T., & Terasawa, K. (2004). Effect of docosahexaenoic acid containing food administration on symptoms of attention deficit/hyperactivity disorder - a placebo controlled double blind study. European Journal of Clinical Nutrition, 58, 467473.
  • Horrobin, D.F., Glen, A.I., & Vaddadi, K.S. (1994). The membrane hypothesis of schizophrenia. Schizophrenia Research, 13, 195208.
  • Ingwersen, J., Defeyter, M.A., Kennedy, D.O., Wesnes, K.A., & Scholey, A.B. (2007). A low glycaemic index breakfast cereal preferentially prevents children’s cognitive performance from declining throughout the morning. Appetite, 49, 240244.
  • Itomura, M., Hamazaki, K., Sawazaki, S., Kobayashi, M., Terasawa, K., Watanabe, S., & Hamazaki, T. (2005). The effect of fish oil on physical aggression in schoolchildren – a randomized, double blind, placebo controlled trial. Journal of Nutritional Biochemistry, 16, 163171.
  • Jazayeri, S., Tehrani-Doost, M., Keshavarz, S.A., Hosseini, M., Djazayery, A., Amini, H., Jalali, M., & Peet, M. (2008). Comparison of therapeutic effects of omega 3 fatty acid eicosapentaenoic acid and fluoxetine, separately and in combination, in major depressive disorder. Australian and New Zealand Journal of Psychiatry, 42, 192198.
  • Joy, C.B., Mumby-Croft, R., & Joy, L.A. (2006). Polyunsaturated fatty acid supplementation for schizophrenia. Cochrane Database of Systematic Reviews Issue 3 Art No: CD001257. DOI:10.1002/14651858. CD001257. pub.2
  • Konofal, E., Lecendreux, L., Arnulf, I., & Mouren, M.C. (2004). Iron deficiency in children with attention deficit /hyperactivity disorder. Archives of Paediatric and Adolescent Medicine, 158, 11131115.
  • Kvinsberg, A.M., Reichelt, K.L., Hoein, T., & Nodland, M. (2002). A randomized controlled study of dietary intervention in autistic syndromes. Nutritional Neuroscience, 5, 251261.
  • Latham, M.C. (1997). Human nutrition in the developing world: Food and nutrition series no.29. Food and Agriculture Organisation of the United Nations (FAO): Rome.
  • Marangell, L.B., Martinez, J.M., Zboyan, H.A., Kertz, B., Kim, H.F., & Puryear, L.J. (2003). A double blind placebo controlled study of the Omega-3 fatty acid docosahexaenoic acid in the treatment of major depression. American Journal of Psychiatry, 160, 996998.
  • McAuley, V., Deary, I.J., Ferguson, S.C., & Frier, B.M. (2001). Acute hypoglycaemia in humans causes attentional dysfunction while non verbal intelligence is preserved. Diabetes Care, 24, 17451750.
  • McCann, D., Barrett, A., Cooper, A., Crumpler, D., Dalen, L., Grimshaw, K., Kitchin, E., Lok, K., Porteous, L., Prince, E., Sonuga-Barke, E., Warner, J.O., & Stevenson, J. (2007). Food additives and hyperactive behaviour in 3 year old and 8/9 year old children in the community: A randomized double blinded placebo controlled trial. Lancet, 370, 15601567.
  • Meeks-Gardner, J., & Grantham-McGregor, S.M. (1994). Physical activity, undernutrition and child development. Proceedings of the Nutritional Society, 53, 2418.
  • Millward, C., Ferriter, M., Calver, S., & Connell-Jones, G. (2004). Gluten and casein free diets for autistic spectrum disorder. Cochrane Database of Systematic Reviews 2004, Issue 2. Art No. CD 003498. DOI: 10.1002/14651858 CD003498 pub2.
  • Mitchell, E.A., Aman, M.G., Turbott, S.H., & Manku, M. (1987). Clinical characteristics and serum essential fatty acid levels in hyperactive children. Clinical Pediatrics (Philadelphia), 26, 406411.
  • Murphy, J.M., Wehler, C.A., Pagano, M.E., Little, M., Kleinman, R.F., & Jellinek, M.S. (1998). Relationship between hunger and psychosocial functioning in low income American children. Journal of the American Academy of Child and Adolescent Psychiatry, 37, 163170.
  • Nemets, B., Stahl, Z., & Belmaker, R.H. (2002). Addition of omega-3 fatty acid to maintenance medication treatment for recurrent unipolar depressive disorder. American Journal of Psychiatry, 159, 477479.
  • Nemets, H., Nemets, B., Apter, A., Bracha, Z., & Belmaker, R.H. (2006). Omega-3 treatment of childhood depression: a controlled, double-blind pilot study. American Journal of Psychiatry, 163, 10981100.
  • National Institute for Health and Clinical Excellence (2008). Attention deficit hyperactivity disorder: full guideline for consultation. http://www.nice.org.uk/nicemedia/pdf/ADHDConsFullGuideline.pdf, accessed 24 June 2008.
  • Nowak, G., Siwek, M., Dudek, D., Zieba, A., & Pilc, A. (2003). Effect of zinc supplementation on antidepressant therapy in unipolar depression: A preliminary placebo controlled study. Polish Journal of Pharmacology, 55, 11431147.
  • Papamandjaris, A. (2000). Breakfast and learning in children: A review of the effects of breakfast on scholastic performance. Canadian Living Foundation http://www.breakfastforlearning.ca/english/resources/materials/papa_report.pdf .
  • Patton, G.C., Coffey, C., Carlin, J.B., Olsson, C.A., & Morley, R. (2004). Prematurity at birth and adolescent depressive disorder. British Journal of Psychiatry, 184, 446447.
  • Peet, M., & Horrobin, D. (2002). A dose ranging study of the effects of ethyl-eicosapentaenoate in patients with ongoing depression despite apparently adequate treatment with standard drugs. Archives of General Psychiatry, 59, 913919.
  • Peet, M., Murphy, B., Shay, J., & Horrobin, D. (1998). Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients. Biological Psychiatry, 43, 315319.
  • Peet, M., Shah, S., Selvam, K., & Ramchand, C.N. (2004). Polyunsaturated fatty acid levels in red cell membranes of unmedicated schizophrenic patients. World Journal of Biological Psychiatry, 5, 9299.
  • Pelsser, L.M., Frankena, K., Toorman, J., Savelkoul, H.F., Pereira, R.R., & Buitelaar, J.K. (in press). A randomised controlled trial into the effects of food on ADHD. European Child and Adolescent Psychiatry, Published online ahead of print: 21 April 2008. DOI 10.1007/s00787-008-0685-7
  • Radia, H. (2005). Fish oils for children with ADHD and other behavioural disturbances. London New Drugs Group APC/DTC Briefing: download at http://www.nelm.nhs.uk
  • Richardson, A.J., & Montgomery, P. (2005). The Oxford-Durham study: a randomized controlled trial of dietary supplementation with fatty acids in children with developmental coordination disorder. Pediatrics, 115, 13601366.
  • Richardson, A.J., & Puri, B.K. (2002). A randomised double blind placebo controlled study of the effects of supplementation with highly unsaturated fatty acids on ADHD-related symptoms in children with specific learning difficulties. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 26, 233239.
  • Richardson, A.J., & Ross, M.A. (2000). Fatty acid metabolism in neurodevelopmental disorder: A new perspective on associations between ADHD, dyslexia, dyspraxia and the autistic spectrum. Prostaglandins, Leukotrienes and Essential Fatty Acids, 63, 19.
  • Richardson, A.J. (2006). They are what you feed them: How food can improve your child's behaviour, learning and mood. London: Harper Thorsons.
  • Schab, D.W., & Trinh, N-H. T. (2004). Do artificial food colors promote hyperactivity in children with hyperactive syndromes? A meta-analysis of double blind placebo controlled trials. Developmental and Behavioural Pediatrics, 25, 423434.
  • Schmidt, M.H., Möcks, P., Lay, B., Eisert, H.G., Fojkar, R., Fritz-Sigmund, D., Marcus, A., & Musaeus, B. (1997). Does oligantigenic diet influence hyperactive/conduct disordered children – a controlled trial. European Child and Adolescent Psychiatry, 6, 8895.
  • Sever, Y., Ashkenazi, A., Tyano, S., & Weitzman, A. (1997). Iron treatment in children with attention deficit hyperactivity disorder – a preliminary report. Neuropsychobiology, 35, 178180.
  • Silvers, K.M., Woolley, C.C., Hamilton, F.C., Watts, P.M., & Watson, R.A. (2005). Randomised double blind placebo controlled trial of fish oil in the treatment of depression. Prostaglandins, Leukotrienes and Essential Fatty Acids, 72, 211218.
  • Sinn, N., & Bryan, J. (2007). Effect of supplementation with polyunsaturated fatty acids and micronutrients on learning and behaviour problems associated with child ADHD. Journal of Developmental and Behavioural Paediatrics., 28, 8291.
  • Sinn, N., Bryan, J., & Wilson, C. (2008). Cognitive effects of polyunsaturated fatty acids in children with attention deficit hyperactivity disorder symptoms: A randomized controlled trial. Prostaglandins, Leukotrienes and Essential Fatty Acids, 78, 311326.
  • Smith, K.A., Fairburn, C.G., & Cowen, P.J. (1997). Relapse of depression after rapid depletion of tryptophan. Lancet, 349, 915919.
  • St Clair, D., Xu, M., Wang, P., Yu, Y., Fang, Y., Zhang, F., Zheng, X., Gu, N., Feng, G., Sham, P., & He, L. (2005). Rates of adult schizophrenia following prenatal exposure to the Chinese famine 1959-1961. Journal of the American Medical Association, 294, 557562.
  • Stevens, L., Zhang, W., Peck, L., Kuczek, T., Grevstad, N., Mahon, A., Zentall, S.S., Arnold, L.E., & Burgess, J.R. (2003). EFA supplementation in children with inattention, hyperactivity, and other disruptive behaviours. Lipids, 38, 10071021.
  • Su, K.P., Huang, S.J., Chiu, C.C., & Shen, W.W. (2003). Omega 3 fatty acids in major depressive disorder: A preliminary double blind placebo controlled trial. European Neuropsychopharmacology, 13, 267271.
  • Sungthong, R., Mo-Suwan, L., & Chongsuvivatwong, V. (2002). Effects of haemoglobin and serum ferritin on cognitive function in schoolchildren. Asia Pacific Journal of Clinical Nutrition, 11, 117122.
  • Tanskanen, A., Hibbeln, J.R., Tuomilehto, J., Uutela, A., Haukkala, A., Viinamaki, H., Lehtonen, J., & Vartiainen, E. (2001). Fish consumption and depressive symptoms in the general population in Finland. Psychiatric Services, 52, 529531.
  • Taylor, E., Sandberg, S., Thorley, G., & Giles, S. (1991). The epidemiology of childhood hyperactivity. Maudsley Monographs No. 33. Oxford: Oxford University Press.
  • Taylor, M.J., Carney, S., Geddes, J., & Goodwin, G. (2003). Folate for depressive disorders. Cochrane Database of Systematic Reviews 2003 Issue 2. Art. No.: CD003390. DOI: 10.1002/1465 1858. CD003390.
  • Toren, P., Eldar, S., Sela, B.A., Wolmer, L., Weitz, R., Inbar, D., Koren, S., Reiss, A., Weizman, R., & Laor, N. (1996). Zinc deficiency in attention deficit hyperactivity disorder. Biological Psychiatry, 40, 13081310.
  • Van de Weyer, C. (2005). Changing diets, changing minds: How food affects mental well being and behaviour. Mental Health Foundation. http://www.mentalhealth.org.uk/publications/?EntryId5=40150&p=4, accessed 10th October 2008.
  • Van Praag, H.M., & Lemus, C. (1986). Monoamine precursors in the treatment of psychiatric disorders. In R.J.Wurtman & & J.J.Wurtman, (Eds.) Nutrition and Brain Volume 7 (pp. 89139). New York: Raven Press.
  • Voight, R.G., Llorente, A.M., Jensen, C.L., Fraley, J.K., Berretta, M.C., & Heird, W.C. (2001). A randomized, double blind, placebo controlled trial of docosahexaenoic acid supplementation in children with attention deficit /hyperactivity disorder. Journal of Paediatrics, 139, 189196.
  • Wardle, J., Cooke, L.J., Gibson, E.L., Sapochnik, M., Sheiham, A., & Lawson, M. (2003). Increasing children’s acceptance of vegetables: A randomized trial of parent led exposure. Appetite, 40, 155162.
  • Wesnes, K.A., Pincock, C., Richardson, D., Helm, G., & Hails, S. (2003). Breakfast reduces declines in attention and memory over the morning in schoolchildren. Appetite, 41, 329331.
  • Williams, A.L., Cotter, A., Sabina, A., Girard, C., Goodman, J., & Katz, D.L. (2005). The role for vitamin B6 as treatment for depression: A systematic review. Family Practice, 22, 532537.
  • World Health Organization (2001). Iron deficiency anaemia: Assessment, prevention and control. WHO/NHD/01.3
  • Wolraich, M.L., Wilson, D.B., & White, J.W. (1995). The effect of sugar on behaviour or cognition in children - a meta analysis. Journal of the American Medical Association, 274, 16171621.
  • Wurtman, R.J., Hefti, F., & Melamed, E. (1980). Precursor control of neurotransmitter synthesis. Pharmacological Reviews, 32, 315335.

Box 1.

  1. Top of page
  2. Abstract
  3. Key Practitioner Message:
  4. Introduction
  5. Early life nutrition and neurocognitive development
  6. School performance and behaviour
  7. Pervasive developmental disorder
  8. Psychiatric illnesses
  9. Conclusions: The best diet for mental health?
  10. References
  11. Box 1.

Normal dietary requirements (Latham, 1997):

Macronutrients

  • 1
     Carbohydrates: fuel for metabolic processes.
  • 2
     Fats: components of cell membranes and stored as fuel. Some fatty acids are only found in certain foods (such as oily fish) and are thought to be essential for optimal brain function.
  • 3
     Proteins: made up of amino acids and form components of cells and of enzymes (proteins facilitating chemical reactions in the body).

Micronutrients

  • 1
     Minerals: widely distributed elements e.g. calcium in bone, iron in haemoglobin (in blood) and iodine in thyroid hormones.
  • 2
     Vitamins: molecules which are important in aiding chemical reactions e.g. vitamin K in blood clotting.

Water

  • makes up 60% of the body weight.

Fibre

not absorbed but aids transit of food through the gastrointestinal tract.