What we eat and drink can have both short-term and long-term effects on our mental health. Food plays an important contributing role in the development and management of disease. But it also helps in the prevention of specific mental health problems such as depression, schizophrenia, attention deficit hyperactivity disorder and Alzheimer’s disease.
A number of cross-country and population-based studies have linked the intake of certain nutrients and foods with depression. People with low intakes of the B-vitamin folate are significantly more likely to be diagnosed with depression than those with higher intakes. B vitamins work as essential co-factors with key enzymes to control the production and balance of our neurotransmitters such as serotonin. Disrupted levels have adverse effects on our brain chemistry.
Researchers are also examining the association between low levels of other B vitamins – B1, B2, B6 and B12 – and the incidence of depression. Studies suggest that as many as 50 per cent of people experienced greater relief of their symptoms when their standard treatments were supplemented with these micronutrients.
Depressant effect
Alcohol has a depressant effect on our mood and the brain. It is also toxic to the body, so we rapidly metabolise it. This process is costly and uses up thiamine or vitamin B1 and can deplete stores of zinc and other nutrients too. As a result, thiamine deficiencies are common in heavy drinkers and can cause low mood, irritability, aggressive behaviour and even longer-term mental health problems.
But our mental health doesn’t just hinge on one or two isolated nutrients. It’s essential to look at groups of foods and patterns of intakes. Strong correlations have been observed between low intakes of fish (by country) and high levels of depression.
A greater adherence to the traditional Mediterranean diet is also associated with a significant improvement in overall health and a significant reduction in the incidence of Parkinson's disease and Alzheimer's disease (BMJ systematic review 2008).
However, there is no one "miracle food" that can boost your brain power, although regularly adding certain foods may help you function at your best.
Brain foods
Wholegrains: Low Gi carbohydrates provide a steady supply of glucose or energy to the brain. The B vitamins found in wholegrains are also important for ensuring a healthy nervous system.
Oily fish: Preliminary studies suggest that people with bipolar disorder who take omega-3 fatty acids have a significantly longer period in which their mood is stable with no episodes of depression. Although more evidence is needed on this, we have plenty of other good reasons to eat oily fish.
Tomatoes: Japanese researchers found that those who reported eating tomatoes two-six times a week were 46 per cent less likely to report mild or severe symptoms of depression than those who ate tomatoes less than once a week. No such association was found for other vegetables.
Berries, especially blueberries: Oxidation can damage brain cells. This oxidative stress plays a role in many diseases associated with ageing such as dementia. Berries and many other fruits and vegetables contain powerful antioxidants pivotal for health.
Nuts: These snack foods contains vitamin E and vitamin B6, making them an excellent source of nourishment for your nervous system and brain.
Leafy green vegetables: Eat one folate-rich green veg a day. This B vitamin helps your brain's serotonin receptors work properly.
Small piece of dark chocolate: The cocoa liqueur contained in the bean is rich in antioxidant polyphenols. Studies suggest that cocoa polyphenols can ease the symptoms associated with anxiety or depression.
Fresh mackerel, sticky honey, soy, sesame and rice wine vinegar dressing
This is a Martin Shanahan omega-3-rich recipe.
Serves 4
4 fillets of fresh mackerel
50ml rapeseed oil
Sea salt
For the dressing
100ml light soy sauce
50ml toasted sesame oil
2 tbsp honey
½ clove garlic, finely chopped
50ml rice wine vinegar
To serve
1 tbsp toasted sesame seeds
To make the dressing: Place all the dressing ingredients in a small pot. Bring to the boil and reduce until the sauce thickens (it should coat the back of a spoon). This can be made while the mackerel is cooking.
To cook the mackerel: Heat a heavy based frying pan and add 50ml of rapeseed oil. Allow the oil to get very hot. Season the mackerel with sea salt, then place flesh side down in the pan. This will help achieve a nice crust on the outside and a moist texture on the inside. Cook for four minutes, then turn the mackerel and cook the other side for two minutes. Pat off the excess oil and place the mackerel on a platter. Spoon over the warm dressing and garnish with toasted sesame seeds.
Aubergine and coconut curry
An old favourite. It's a source of B vitamins, it's simple to prepare and freezes well.
Serves 4
1 tbsp olive oil
1 medium aubergine, cut into bite-sized (2cm) chunks
1 medium onion, chopped
1in piece ginger, peeled and coarsely grated
1 red chilli, chopped
1 heaped tbsp garam masala or mild curry paste
400g can chickpeas, drained and rinsed
1 large sweet potato, peeled and cut into chunks
400g can chopped tomatoes
400g can reduced-fat coconut milk
15g (handful) fresh coriander leaves
125g spinach leaves (baby or tender leaf)
Optional, to serve: 125g pot low-fat Greek-style natural yoghurt (not included in nutritional analysis).
Heat the oil in a large non-stick pan and toss the aubergine around until golden brown and beginning to soften. Lift out on to a plate with a spoon, then add another 1 tbsp olive oil to the pan and fry the onion over a medium heat for at least 10 minutes until softened.
Add the ginger, chilli and garam masala to the onion, stir for 2 min.
Add the aubergine, chickpeas, sweet potato, tomatoes and coconut milk to the pan. Bring to the boil, then simmer gently until the sweet potato is just tender – about 10-12 minutes.
Taste and add seasoning. Just before eating, tear the coriander into rough pieces and stir into the curry with the spinach leaves – they’ll wilt in the heat of the pan.
If you want to, top with Greek-style yoghurt.
Paula Mee is a dietitian and a member of the INDI. pmee@medfit.ie or tweet paulamarymee
