It’s not an accident that we turn to food when we want to celebrate an event or when we feel we need for a little “pick-me-up”. Pleasurable food triggers the secretion of a powerful chemical called dopamine, which has a direct and instant effect on our mood. But we all know that this effect is short lived – so chocolate cake is possibly not the wisest tool to help us with our mental health… Let’s see what other aspects of our diet could have more lasting & powerful effects.
Can our diet have a sustainable impact on our mental health?
A recent study called the SMILES trial suggests that dietary changes could be a useful addition to other treatments such as drugs or therapy. In this small randomised control trial, they studied how a diet intervention could help people with moderate to severe depression (sample size = 67). Their results were promising: the group that received the dietary support showed greater improvement in their depression score, and reduced anxiety, compared to the control group.
But what sort of food has a positive impact your mental health? Well, as so often in nutrition science, there isn’t any definite and strong answer. But fortunately, we have some good evidence that a diet:
rich in plant food;
that includes enough of key nutrients (specific vitamins, minerals and omega 3);
that is supported by other lifestyle aspects such as regular exercise and good sleep;
is associated with better mental health.
Eat plenty of plant-based food for a happy gut
Did you know that our large intestine is home to trillions of micro-organisms called our ‘gut microbiota’? We are the host of more than a kilo of microbes, mainly bacteria, and these play an important role on our overall health, physical and mental. We need to take care of them by feeding them what they like the most: dietary fibre and polyphenols, both found in plant-based foods. And they like variety! Therefore, the trick is to eat a wide range of veg, fruit, wholegrains, pulses, nuts and seeds. A good rule of thumbs is to aim at 30 different sources of plant-based foods a week.
Keep key minerals and vitamins topped up
There is no need to go overboard with minerals and vitamins, but it is worth making sure that we get enough, as low levels have been linked to lower energy, lower mood, anxiety and depression.
Vitamins of the B complex (in particular B1, B3, B12 and Folate) have been associated with fatigue and feeling depressed.
Vitamins B1 is found in wholegrains and fortified cereals.
Vitamin B3 is found in meat, seafood, poultry, peanut butter, beans and tofu.
Vitamin B12 is found in animal-based products (meat, fish, poultry, dairy product). If you are vegan, you might want to consider supplementing.
Folate is found in dark green vegetables, legumes (beans and peas), seeds.
Almost a quarter of the UK population is presenting low levels of vitamin D, and depression has been linked to vitamin D insufficiency. Although we find a bit of vitamin D in some fortified milk and fatty fish, it is hard to get enough through our diet. It is mainly synthesised by our body through exposure to the sun and during the UK winter months (from October to April) we simply don’t get enough. This is why Public Health England recommends everyone to take a supplement of vitamin D3 of at least 400 IU.
While lack of Zinc and Selenium have been linked to depression and negative mood, low Magnesium has been associated with anxiety and low iron with fatigue. Make sure that good sources of these are included in your diet.
Zinc is found in animal-based foods (meat, seafood, dairy) and nuts
Selenium is found in meat, fish, eggs and brazil nuts
Magnesium is found in nuts, legumes, soy, oats, dark green vegetables
Iron is found in meat, poultry, seafood, eggs, dried apricots, legumes, tofu.
Add some oily fish to your weekly meal plan
Omega 3 fatty acids, found mainly in oily fish (salmon, trout, sardines, tuna, mackerel) have been shown to play a role in our cognitive function and to help with depression symptoms – as well as lowering the risk of depression. We should aim at eating 2 portions of fish a week, one of which should be an oily fish. For vegans, supplementation should be considered.
And remember that diet is one lifestyle element among others
Let’s not forget that other lifestyle aspects, in addition to diet, can help. Regular exercise and good sleep hygiene will also have an important impact on our mental health.
In a nutshell, although many aspects of our mental health aren’t in our control, looking after our diet, alongside some exercise and good sleep, could give a little help to our mental health. By increasing our intake of fruit and veg, legumes, wholegrains, by adding some fish, and by focusing on a broad and varied diet, we are supporting our overall wellbeing.
 Jacka, F.N., O’Neil, A., Opie, R. et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med 15, 23 (2017). https://doi.org/10.1186/s12916-017-0791-y  Lai, J. S., Hiles, S., Bisquera, A., Hure, A. J., McEvoy, M., & Attia, J. (2014). A systematic review and meta-analysis of dietary patterns and depression in community-dwelling adults. The American journal of clinical nutrition, 99(1), 181–197. https://doi.org/10.3945/ajcn.113.069880  Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota's effect on mental health: The gut-brain axis. Clinics and practice, 7(4), 987. https://doi.org/10.4081/cp.2017.987  https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/