Sometimes we read articles that highlight one, or just a few aspects of diet and mental health, so maybe one gets emphasised as a necessary nutritional addition to what is thought of as good nutrition in children at that time. We may even see it translated into a product such as HiQbread with added essential fatty acids [EFAs].
Reading the article “Diet and Mental Health in Children” by D Tomlinson, H Wilkinson & P Wilkinson, in Child and Adolescent Health Vol 14, No 3, 2009 148 – 155 highlights the need for thoughtful parents to stop and think about what is most important when we think about diet and mental health. It also brings up a challenge to dietitians and nutrition scientists to delve into the research on the outcomes of various nutrient deficiencies and collect the information on any mental health problems that may have been found along with the physical deficiency symptoms.
These comments are made as a dietitian with a special interest in mental health after 30 years of research into diet and ADHD, and into feeding problems in children, and who also has a public health interest including a position as Adviser in Nutrition and Dietetics to Qld Health for four years.
Just as there are connections between nutrition and physical development, a connection between nutrition and mental health should be considered. Tomlinson and colleagues provide an overview in this detailed article that is recommended reading. It is a difficult topic to consider since there is a necessary public health orientation as well as review of specific nutrients currently being discussed as treatments for particular mental health problems.
I will only comment where an aspect is of interest. The reviewers discuss lower IQ in low birth weight babies acknowledging that this can be due to impaired nutrition and/or, or as well as, any medical reasons for the low birth weight, or high cigarette smoking in pregnancy. Higher verbal IQ was found associated with high maternal fish intake, also allowing higher iodine intake. But does increased fish intake select parents who value a broad nutrition intake, so are likely to value many other positive parenting practices?
Breastfeeding is reported as beneficial importantly noting that this is independent of social class, effect of genetics on decision to breastfeed and maternal cognitive ability. But the higher IQ was only in one genetic group with regard to fatty acid metabolism. I support their comment that this and other interactions between genetics and diet should be further investigated.
One important aspect is the interaction between nutrition and all the social and environmental factors that are likely to affect mental health. This is a big topic and difficult to tease out so not much useful research is available. Once work on the direct likely effect of various dietary deficiencies on mental health are known that work can be furthered. However the link between nutrition and all the psychosocial aspects should be mentioned so a likely connection is recognised. I remember when the role of infection was first freely discussed as interacting with poor nutrition to worsen health. Children in famine prone countries may have compromised nutrition but few nutrition related social problems. Children in countries where famines are rare may be neglected and poor provision of nutrition may be one part of this, so nutrition and neglect interact.
Looking at diet from a public health point of view would lead to more discussion of the need for ensuring adequate iron in all children, with its known effect on fatigue where learning and behaviour are concerned. Perhaps some of the benefit from ensuring breakfast intake is due to improved iron status.
It is also important to remember that ensuring breakfast contributes to adequate energy intake. Ensuring adequate energy is always seen as the priority in physical health and should also be mentioned as the priority for mental health. Adequate energy intake improves the chances of improved protein intake which is also a key priority. The need for adequate nutrition is summarised in a table at the beginning of the review but later when particular problems are considered the need for adequate energy, protein and iron may be presumed but are not noted as the first priorities or emphasised as they should be.
When writing of nutrition and physical health there is a need to consider research on the outcomes of a deficiency of each nutrient. Applying this to mental health would take a whole book but would give a very useful view. It would allow discussion of whether mental health problems of particular types occur more often where particular nutrients are deficient. It would be noted that the particular cluster of symptoms that are said to occur with EFA deficiency in western countries are not noted as occurring in countries most likely to have a deficiency. This would be in countries with a marginal food supply and where almost no fish are eaten. Perhaps EFA deficiency symptoms only occur in those with some metabolic disorder. Both of these issues need to be investigated further.
When epidemiological studies of the incidence of food related disorders such as coronary heart disease are done differences in food intake can be correlated to differences in its incidence. When main mental illnesses are viewed epidemiologically it is noted that the incidence is similar throughout the world. If lack of particular nutrients was a significant factor it should have affected the incidence in particular countries.
What the article does do well is to review the topics that are of particular interest at present.
Food neophobia [avoidance of new foods] has been much discussed in relation to feeding problems in the general child feeding problem literature. This review reports that surveys of twins concluded that neophobia is a highly heritable trait, and that management can reduce aversion. So it should not affect sufficient range of foods being eaten. Work done by this author on eating development and eating delay shows that eating problems can be addressed using a developmental approach. See Chapter 2 in Fussy Baby. It should be noted here that children in countries with limited food supply are still reported as being very selective or “fussy”. This lends support to what I prefer to call “supersensitivity” rather than neophobia in some children being inherited. See Chapter 4 in Fussy Baby. It could also be noted here that diet responding children are more often described as fussy.
ADHD is discussed in detail, overall acknowledging that additives do affect some children. Since nutrition in food can be considered as part of public health and nutrition policy the role of additives is also often considered under this umbrella. While emerging research has shown the effect on behaviour to be broader than just in ADHD children it is probably wise to consider this aspect of diet separately as part of a treatment effect for a particular sub group. It is important to stop at this time and note that the role of suspect substances affecting ADHD is not related to nutrition but to a pharmacological effect of some food chemicals in some children. Another point to note is that these suspect chemicals and whole foods affect physical symptoms such as eczema, headaches and tummy aches as well as behaviour. Susceptibility is in the child not in the diagnosis of ADHD. Where diet has an effect it changes irritability, sleep, and mood as well as ADHD features. See Review covering all the research up to 1998 by this author. Nutritional status is not relevant to adverse food reactions, though all children considering elimination diets should be checked for adequate nutrient intake before and after diet implementation.
Tomlinson and others’ review includes all the useful recent diet and ADHD studies since 1998. These studies also show a role not just for additives but also for some whole foods suggesting a role for individually tailored diets. Overall, studies show diet investigation should incorporate additives, food chemicals and whole foods. The reviewers recommend support for parents who exclude additives on the basis of reactions noted in their children. Clinical research done in Australia which has refined the diet and the diet process is unfortunately not mentioned.
Where additives are concerned we do not know how the effect happens, what the mechanism is and research cannot describe blood levels of problem metabolites. While clinical research has shown diet benefits, and the effective diet investigation process, the lack of a clear mechanism impedes acceptance.
The review describes and assesses the breadth of essential fatty acids and ADHD literature well. The fact that those advocating the EFAs have a hypothesis including possible function in the body, and variations in blood level measurement of metabolites and described deficiency symptoms all contribute to validity. However the usual validation by seeing deficiency symptoms and determining separately which foods and nutrients prevent them has not occurred. Nor is the normal range of EFAs in the blood known, so what is outside that range is not yet known.
The use of EFAs and possible food sensitivity have both been researched sufficiently to show that each may have some beneficial role, but they have in common the lack of knowledge as to exactly which children may benefit from either intervention. However my research has indicated those most likely to respond to dietary treatment. See Thesis on diet and behaviour, and the book Are You Food Sensitive?
A good enough diet is possible in most western societies. But insufficient total energy and protein, and other nutrients, are more likely in countries with an unreliable food supply. Iron deficiency is likely to affect fatigue in children and therefore attention. Are mental illnesses more likely there? We have no evidence of this.
Where mental health is concerned the first priority is to ensure that each child has sufficient energy overall. This can be assessed using normal height and weight tables. Differences from the expectations since birth, unless low birth weight was present, can be noted. For the reasons mentioned above ensuring breakfast is important. Intake of important nutrients such as protein (most easily assessed by adequate milk and cheese intake, and a protein with the evening meal), and iron can be checked. When interesting discussions of particular nutrients such as use of EFAs arise, the importance of normal nutrition should not be forgotten, and the use of EFAs in doses above maximum likely normal intake as a treatment for a disorder, should be considered separately.
Joan Breakey Dietitian specialising in food sensitivity