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Mental health problems are believed to be the result of a combination of factors that appear to play a role in predisposing individuals to developing a mental health difficulty. These include genetics, age and environmental factors. More recently, however, there is a growing wealth of evidence, which highlights the ever-increasing role that food and nutrition plays in our emotional status. The evidence suggests that may food play an important contributing role in the prevention, progression and management of mental health problems including, Depression, Anxiety, Schizophrenia, Attention Deficit Hyperactivity Disorder (ADHD), and Alzheimers Disease. Research is ongoing in this area and the role of nutrition in mental health has yet to be fully understood and embraced. Much of the proposed benefits require further research before we can equivocally relate specific mental health problems to our nutritional status.


There appears to be a growing burden of mental ill-health worldwide which ultimately poses an ongoing financial burden on healthcare systems. Demographics vary from one country to the next with some countries statistics suggesting that one in four people are likely to experience a mental health problem at some point in their lifetime. Most studies indicate that there appears to be no respite in the pace and impact of the growing burden of mental ill-health.

Causes and symptoms

There is a plethora of anecdotal, clinical and controlled studies that highlight the importance of nutrition as one part of the jigsaw in the prevention and management of positive mental health. Other causative factors include genetics and environmental factors


Diagnosis of a mental health problem is usually made by a trained clinician, for example, a Psychiatrist or a General Practitioner (GP). Confirmation of a diagnosis is usually made following completion of standardised assessment tools and a full psychiatric assessment.


Treatment varies depending on the type of mental health problem. However, more and more, lifestyle factors including exercise are seen as a first-line treatment for people suffering with symptoms of Depression. If required, this may then be followed by a talking therapy, for example, Cognitive Behaviour Therapy (CBT) or a guided self-help approach with evidence-based books, called ’Bibliotherapy’. Medication may also be required as an adjunct to the aforementioned therapies, for example, Selective Serotonin-reuptake inhibitors (SSRIs). Where individuals do not respond to these treatments, Electro convulsive therapy (ECT) may be explored. For other types of mental health problems, medication may be commenced on diagnosis, subject to the symptoms the individual is experiencing. In cases where the individual is deemed as requiring support and intervention on a more intensive basis, inpatient treatment may be necessary. This is usually considered if the individual is thought to present a risk either to themselves or others as a consequence of their mental health difficulty.

Nutrition/Dietetic concerns

The food we eat plays an important role in our physical and emotional wellbeing at every stage of our lives from the preconceptive nutrition of a mother planning her pregnancy through to weaning, adolescence, adult and older adulthood. The benefits to babies of breast versus formula milks in terms of brain function is well documented. These benefits are thought to be as a consequence of increased levels of Essential fatty Acids (EFAs) in breastmilk. Many studies have reviewed research over the past number of years, which clearly support the notion that the inclusion of breakfast improves daily and long-term academic performance in children. Similarly, research studies suggest that when children are hungry, behaviour is worsened. Conversely, the provision of nutritious meals helps decrease fighting and absence whilst simultaneously increasing attention. A number of studies suggest that supplementation of the diet can impact on the behaviour of offenders and have a

Diet-mood connection

NutrientFood sourcesNeurotransmitter/mechanismProposed effect
ProteinMeat, milk, eggs, cheese, fish, beansDopamine, NorepinephrineIncreased alertness, concentration
Carbohydrate (CHO)Grains, fruits, sugarsSerotoninIncreased calmness, relaxation
CaloriesAll foodsReduced blood flow to the brainExcess calories in a meal is associated with decreased alertness and concentration after the meal

(Illustration by GGS Information Services/Thomson Gale.)


Amino acids—These are the building blocks of protein

Carbohydrates—carbohydrates are a major source of energy. Carbohydrates in the diet are principally made up of starches, sugars and dietary fibre.

Fats—Fat is a concentrated source of energy. Foods that are high in fat provide a lot of energy and are good sources of vitamins, A, D, E, and K and provide essential fatty acids.

Minerals—These are elements which are essential for the body’s normal function including calcium, iron, phosphorous, magnesium, sodium, chloride, iodine, manganese, copper, and zinc

Proteins—These are large molecules which are made up of thousands of amino acids. The primary function of protein is grwth and repair of body tissues.

Serotonin—A neurotransmitter and a hormone. As a neurotransmitter is acts like a chemical in the brain which help transmit signals in the brain

Tryptophan—This is an amino acid which plays a role in the manufacture of serotonin

Vitamins—These are compounds required by the body in small amounts to assist in energy production and in cell growth and maintenance. They are essential for life and with the exception of vitamin D, cannotbe made in the body. They should ideally be consumed from food. However, individuals who struggle to eat can obtain their vitamin requirements from dietary supplements.

positive impact on reduction of antisocial behaviour (Gesch, 2002). However, further studies are necessary to replicate these findings amongst the general population.

Most people have a good understanding of the effects of nutrition on our physical health. The ongoing health-promotion messages both in the media and in health-care settings appear to have reached the general public. People now accept the effects that a diet high in saturated fat, salt and sugar plus a diet low in fibre, fresh fruit and vegetables can have on our long-term health. The public are aware that a unhealthy dietary intake increases the risk of Coronary Heart Disease (CHD), Type 2 Diabetes, Hypertension and some types of Cancer. Less awareness appears to be evident in terms of how the diet can impact on our emotional status and mental health. However, anyone who has ever drank alcohol, tea or coffee or eaten chocolate recognises how certain fluids or foods can influence our mood. Perhaps one of the reasons why we do not associate food with mood is due to the delay in seeing an immediate effect, for example, eating some foods which are raw or undercooked can cause people to become very ill and consequently develop an immediate association between a particular food and physical discomfort. However, the impact of what we eat on our mood is usually a slower less tangible process.

Arguably, the contribution of diet to mental health status is complex and affected by many other complex issues. Nonetheless, we do know that diet affects our physical health, which in turn can impact on our emotional status and wellbeing. A restrictive dietary intake, which is low in essential nutrients, is unlikely to meet the daily recommended nutritional requirements to help minimise the risk of development of nutrition-related illnesses, including, iron-deficiency anaemia, low energy levels and poor concentration. Similarly, dietary intakes high in fat or sugar, can frequently be low in essential vitamins and minerals despite meeting our energy or calorie requirements. Therefore, our brain like the heart or liver is sensitive to the foods we eat on a daily basis. To remain healthy the brain needs different amounts of the following nutrients; complex carbohydrates, EFA’s, amino acids, vitamins and minerals and water.


In order to understand the role individual nutrients play in the body it is important to briefly look at the structure of the brain and how it functions.

Structure of the Brain and Neurotransmitters

The brain contains billions of nerve cells, which allow the brain to communicate with itself and other parts of the body. These nerve cells are made up of fat primarily, which is derived from the diet. Chemicals, called neurotransmitters help the nerve cells communicate with each other and they are made from amino acids, which are often derived from the diet. Amino acids are the building blocks of Protein. The most widely known neurotransmitter is called Serotonin and is derived from an amino acid called Tryptophan. Other transmitters include Acetylcholine, Dopamine, Adrenaline, Noradrenaline and 4-aminobutyrate (GABA). A sufficient balance of these neurotransmitters is essential for good mental health and they play an important role in feelings of anxiety, memory and cognitive status. The frequent consumption of certain foods can hinder and decrease the effectiveness of these chemicals in the brain, for example, foods high in saturated and trans-fats. Conversely, certain foods can help nourish the brain by helping it to release an efficient balance of neurotransmitters. Similarly, foods, which are high in antioxidants, can help protect the cells in the brain from becoming damaged.

In addition, to feeding the brain with foods that will help regulate neurotransmitter activity and protect the brain from damage, mood can also be improved by ensuring that the diet contains adequate amounts of complex carbohydrates, essential fats, amino acids, vitamins and minerals and water.


FACTS ABOUT CARBOHYDRATES AND WEIGHT LOSS There is much confusion amongst the public about carbohydrates and their role as part of a healthy diet. Starchy carbohydrates have wrongly been at the receiving end of misleading messages in the media which suggest that ‘low-carb’ and ‘carb-free’ options are the way to go if you are trying to lose weight. There is little evidence to support these theories.

  • When energy intake equals energy expenditure, weight remains unchanged.
  • When energy intake exceeds expenditure, weight increases.
  • When energy intake is less than expenditure, weight will decrease.

Therefore, if someone hypothetically requires 3000 calories per day and they eat 3500 calories worth of carrots daily, they may still gain weight as their energy intake is greater than their expenditure, even though what they are eating is low in calories.

In summary, the message is; daily calorie intake should be made up of calories from carbohydrates, proteins, fats, vitamins and minerals, from a variety of foods. There should not be a need for people to completely exclude a major food group such as starchy carbohydrates to support weight loss and in fact this would not be recommended as part of a healthy diet.

CARBOHYDRATES AND THE BRAIN The brain runs on a fuel called glucose and it is the largest user of glucose within the body. Glucose is the breakdown product of carbohydrates. However, some carbohydrates are more preferable than others in terms of fuelling the brain, because they release the glucose at a slower and more efficient rate. These more efficient fuels for the brain are derived from starchy carbohydrates. However, please note that there are different types of carbohydrates, complex (also known as starchy), sugary and fiber-type foods.

COMPLEX CARBOHYDRATES Sometimes referred to as ‘starchy’ or ‘slow release’ carbohydrates. Foods from this group should be included at each mealtime because they are broken down slowly in the body and therefore give us a slow release of energy over a long period of time. These fuels help us to feel full for longer after we eat meals high in starchy carbohydrates. They therefore help prevent or reduce the need for snacking. Starchy foods which contain fiber enhance this effect further and therefore work even more efficiently. Starchy foods tend to be high in nutrients, for example, B vitamins. These foods are essential for maintaining and sustaining energy levels. Choosing foods that take longer to be broken down helps ensure that the brain receives a relatively constant source of fuel. These foods also play a vital role in helping to support an efficient metabolism. If the brain does not receive the correct fuels on a regular basis or energy intake is inadequate the metabolic rate may slow down, thereby making the body more prone to weight gain.

Sources of starchy carbohydrates: Breads, potatoes, pasta, rice, cereals, oats, cous cous, bulgar wheat, yams, sweet potatoes, green banana, plantain, noodles. Fibre-rich options include, brown rice, wholemeal pasta and wholemeal cereals.

Sources of sugary carbohydrates: Chocolate, cakes, sweets biscuits and alcohol.


EFA’S Despite current recommendations to watch our fat intake, fat is essential for life. From a physical health perspective fat provides us with essential fat-soluble vitamins A, D, E and K. From a mental health perspective, the brain is composed of a high percentage of fat and a high percentage of this fat comes from EFAs, omega-3 and omega-6. These are called ’essen-tial’ as they cannot be made in the body and need to be obtained from the diet. These EFAs are a vital part of the structure of the brain cells and for promoting communicating between the cells in the brain.

Much research has been conducted on omega-3 oils to date, which indicates that these fatty acids can have positive protective benefits in terms of heart disease. More recently researchers have become interested in the potential benefits of omega-3 in behaviour and positive mental health. However, there is wide variation in outcomes of studies with some researchers who have reviewed the evidence suggesting positive benefits on mood whilst other studies discount this. Interestingly, a study from 2003, suggested that the levels of depression amongst people lining in the Artic and Subartic regions was rising at the same time that traditional diets, which were high in EFAs were being replaced by more processed foods.

Other mental health problems have been researched to investigate if there is a relationship between diet and Alzheimer’s disease and Schizophrenia. Much research is still required in these areas before any definitive associations can be made. Nonetheless, as at 2007, many studies have indicated that there is a relationship between higher intakes of fat with increased incidence of Alzheimer’s disease. Other research suggests a link between lower levels of poly-unsaturated fatty acids (PUFAs) and Schizophrenia (Peet et al., 1995).

Sources of omega-3 include oily fish, for example, mackerel, pilchards, sardines, fresh tuna, salmon, herring, anchovies, kippers, whitebait and trout. Vegetable oils including linseed, flaxseed, rapeseed and walnut also contain omega 3.

Amino Acids

Amino acids are the building blocks of protein and neurotransmitters are made from amino acids. Some amino acids are ‘essential’, meaning we need to obtain them from our diet, whilst the body itself can make ‘non-essential’ amino acids. Therefore, inadequate intake of certain amino acids may contribute to insufficient levels of neurotransmitters in the brain.

The most widely researched amino acid is trypto-phan and its relationship with the neurotransmitter serotonin. Serotonin can play a role in mood, eating and sleep patterns. One of the features of depression is a reduction in the amount of serotonin in the brain. As Tryptophan is a precursor to serotonin it has recently been the focus of much research attention. Tryptophan is found in many foods including eggs, lean meat and beans. However, to produce serotonin, the body also requires the availability of other enzymes, vitamins and minerals. Absence of any of these essential components may impact on the ability of the body to manufacture serotonin.


A number of different B vitamins play a role in positive mental health, for example, a deficiency of the B vitamin (niacin) can lead to sleeplessness, fatigue, depression and memory loss whilst a deficiency of riboflavin can lead to insomnia and weakness. Numerous physical signs and symptoms are also associated with B vitamin deficiency. Some studies suggest that there may be a correlation between folate or folic acid and Depression and that those with low intakes were more likely to be diagnosed with Depression than those with higher intakes.

Sources of B vitamins include some meats and offal, fortified cereals, eggs, milk and some vegetables.


SELENIUM Selenium plays an important role in our immune system functioning, reproduction and thyroid hormone metabolism. There are some research studies, which suggests that selenium plays a positive role in mood and energy levels and that people with a low selenium intake are more likely to be anxious, depressed and tired. Sources include; walnuts and brazil nuts, seafood, chicken, beef, bran, broccoli, mushrooms, onions, wheat germ and whole-grain products.


Studies into the causes of Schizophrenia suggest lower levels of antioxidant enzymes in the brains of people with Schizophrenia thus indicating that their brain cells may be more vulnerable to oxidation. However, further research is required in this area before any conclusive correlations can be made. Similar research into the role of antioxidants in the prevention of Alzheimers Disease is also ongoing.


Water makes up more than three-quarters of the brain and is therefore an essential element in ensuring the chemical processes in our bodies work efficiently. We lose water daily through waste, sweat and bodily fluids. When we sweat excessively through exercise or in warm temperatures we lose large volumes of fluid. It is essential that we replace these fluids. Average fluid requirements for adults are approximately 35ml/kg/ day. Signs of dehydration include tiredness, restlessness, irritable behaviour, weakness, constipation, loss of concentration and headaches. More severe symptoms, can include low blood pressure, fainting and on occasions heart failure.

Sources of fluids: water is one of the best sources of fluid for the body. Other fluids including squash, fruit juice and milk. Tea and coffee can also contribute to your daily fluid intake, however, non-caffeinated drinks are preferable as caffeine (and alcohol) can have a diuretic effect and exacerbate dehydration.

HOW MUCH FLUID DO I NEED PER DAY? An average adult should aim for 35 mls of fluid per kilogram of body weight. Therefore, a 70 kg individual requiring 35 mls per kg per day would in total need;

  • 70kg x 35 mls = 2450 mls per day
  • Weight x 35 mls = minimum fluid requirements for the day


Whilst the above information provides some details in relation to the role of nutrition and mental health they are by no means a sole cure for depressive symptoms for the majority of individuals. Some foods can help lift your mood, but if there is an underlying medical cause for the symptoms it is important that this is dealt with properly. Medical advice should be sought when individuals experience signs and symptoms of Depression before starting any new dietary regime. If unsure please request a referral via your GP to a Registered Dietitian


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Annette Laura Dunne, BSc (Hons) MSc RD