Diet can seriously affect your brainpower.

If you eat poorly, you can lose concentration easier, become physically and mentally stressed; and you simply don't learn as well when you are studying.

The brain is fed by glucose, which is broken down from the food we eat. The types of food we eat, and when and how much we eat can affect mood, behaviour and brain function in a number of different ways, primarily by altering the chemistry and functioning of the brain. An obvious and often dramatic example is the affect of coffee on a person’s mental state. People often experience heightened energy, alertness and possibly agitation after drinking a cup of coffee. The effects of nutrition on mental health are not always instantly observable, and may occur over a matter of hours or years. For example, skipping a meal can result in a lack of energy supply to the brain a couple of hours later and may reduce a person’s motivation and problem-solving ability (among other things). In a longer term example, deficiencies in the B-vitamin Thiamin can lead to Wernicke-Korsacoff syndrome that can result in vision changes, confusion and impaired memory.

Eating regularly
To maintain a positive, stable mood, it is beneficial to eat regular meals. The brain requires energy to function, so if energy requirements are not met the body’s processes start to slow or shut down. When this happens mental functioning is affected, and can result in symptoms such as low energy levels and motivation, reduced cognitive functioning, irritability and a depressed mood state. Another aspect of eating regularly is to keep blood sugar levels balanced. As mentioned, when we eat food part of it is broken down into glucose that feeds the brain. As this gets used up between meals, the blood sugar levels drop. If the blood sugar levels drop too low, people may experience depressed mood, irritability, an inability to cope, anger or fatigue.

High blood sugar levels can also affect moods (not to mention a person’s overall health), for example eating foods with a high glycaemic index (GI - this will be discussed in further detail later in the chapter) that cause the blood sugar levels to spike can also affect mood and behaviour, potentially causing irrational behaviour, aggression, mood swings and fatigue. Some ways to prevent blood sugar level fluctuations include eating every four hours or so (this may include a small healthy snack between meals); eating at least three meals a day (including breakfast); and eating low GI foods that take longer to be absorbed so release glucose into the bloodstream at a slower rate.

Food and Neurotransmitters
Neurotransmitters are chemicals in the brain that allow for communication between neurons - nerve cells that make up the nervous system. Neurotransmitters play an important role in mental health, and contribute to a variety of mood states. For example, serotonin is associated with states of relaxation, calm and sometimes drowsiness. Stable serotonin levels are associated with positive moods and a greater sense of wellbeing. Dopamine and norepinephrine are associated with states of alertness and concentration. Dopamine is a natural energiser and is thought to reduce depression. Low levels of these neurotransmitters are implicated in a variety of mood disorders, such as depression, anxiety, bipolar and eating disorders.

Neurotransmitters need precursors (building materials) to reproduce, and these precursors are largely gained through the diet. Insufficient amounts of the precursors means the brain can not produce adequate amounts of neurotransmitters which can result in mental disorders or disruptions.

The precursor for serotonin is tryptophan – an amino acid. Amino acids are the building blocks of protein, so tryptophan is found in high protein food such as dairy products, meats and eggs. Eating sufficient amounts of these foods can keep the serotonin levels stable. Without adequate tryptophan in the diet, levels of serotonin in the brain can drop, affecting the person’s mental health. Serotonin levels can also be increased by the consumption of carbohydrates, as carbohydrates triggers the release of the hormone insulin, and an increased insulin level causes more tryptophan to enter the brain. Higher levels of tryptophan allows for higher levels of serotonin to be produced.

The precursor for dopamine is the amino acids phenylalanine and tyrosine, which can be found in foods such as eggs, almonds, meat, grains, avocado and bananas (amongst others). Like serotonin, without adequate levels of the amino acids, insufficient levels of dopamine are produced and may result in mood and other disorders.

So a diet that includes sufficient amounts of protein is important for mental health. Carbohydrates also play a role in mental health. As mentioned, carbohydrates help to increase serotonin levels however, it is important to note how different types of carbohydrates can produce a more positive or more negative effect.

Carbohydrates
Ultimately, carbohydrates are broken down into glucose that is absorbed into the bloodstream. Depending on the type of food, this can occur at a rapid rate or more slowly. Taking a closer look at sugar, the link between sugar and mental health is becoming more and more observed in the media, books, and research. Because the brain relies on a steady supply of glucose, the more unstable the supply of glucose to the brain, the more unstable the mood. Sugary and refined foods (such as white bread and cakes) are absorbed into the bloodstream quickly, and create a short burst of energy that quickly wears off and creates a feeling of tiredness and a low mood. It is not uncommon to hear people speak of manic, possibly aggressive states during a sugar peak, followed by a state of depression, and fatigue. Sugar further affects mental health by using up mood enhancing B vitamins during conversion to energy, depleting the levels of B vitamins.

Less processed carbohydrates such as whole grains, pulses, fruit and vegetables are broken down and absorbed more slowly, so provide a more consistent supply of energy over time, without the peaks and crashes of sugary and refined foods. So these types of food are a preferable source of glucose to keep levels more stable over time.

It was briefly mentioned previously about high and low GI foods. GI refers to Glycaemic Index, which provides an indication of how much the blood glucose level will rise when food is consumed. Sugary and refined foods that create a rapid surge of glucose in the bloodstream are classed as High GI, and foods that are broken down more slowly and absorbed over time such as whole grains, pulses, fruit and vegetables are classed as Low GI. For overall mental and physical health it is generally recommended to eat more low GI foods, and less high GI foods.

Fats
Healthy fats also play a role in mental health. Fats form part of our brain structure, including the myelin sheath, and is important in supporting communication within the brain. One fat that gains the most attention in the area of mental health is Omega-3 fatty acid. It has been suggested that there is a link between low levels of Omega-3 and depression. The most common dietary source of Omega-3 is from fish, particularly oily fish such as salmon, sardines, tuna and mackerel. You can also get Omega-3 from flaxseeds, nuts, and other plant-based sources.

Vitamins and Minerals
Vitamins and minerals also contribute to mental health, many of which cannot be produced by the body, so must be gained from dietary sources. Deficiencies in some vitamins and minerals can result in psychological disorders. For example, low levels of many of the B vitamins, vitamin C, magnesium, zinc, and others are associated with depression and other psychological disturbances. Care must be taken to eat a variety of nutritious foods to ensure vitamin and mineral requirements are met.