Food and Mood
Our brain utilises 20-25% of our energy intake every single day. Considering our brain is responsible for our thoughts, feelings, ideas and motivation - we should aim to feed it properly! It doesn’t just require calories though - the brain uses vitamins and minerals for all cellular activity including production of neurotransmitters and action potentials. Previously, nutrition wasn’t considered in mental health research but lately there is some really convincing evidence that our diet impacts our brain in a variety of ways.
The SMILES Trial
One of the most promising studies is called the SMILES Trial which compared those on a clinically defined poor diet: which was low in fibre, fruit and vegetables and lean protein, high in sweets, salty foods and processed meats. Participants were either assigned to a nutritional intervention group or a befriending control group. Anxiety, depression and general mood were assessed at the beginning and end of the study along with various biochemical markers such as cholesterol levels and fasting blood glucose levels. The group who had dietary intervention had reduced severity of anxiety symptoms and were 4 times more likely to be in remission following therapy treatment.
This study led the way for research on the importance of diet for mental health and has been replicated several times, showing that, at least for some people, diet can contribute to depressive symptoms.
The dietary intervention which was used was based upon the Mediterranean diet which means a high intake of fruit and veg, legumes, wholegrains, nuts, seeds, oily fish and plant oils. You don’t need to follow a Mediterranean diet to have a healthy brain but we can definitely utilise some of the basic components of this way of eating to influence both our brain and general health.
Breaking Down the Meditterranean Diet
Oily fish such as sardines, salmon, fresh tuna and mackerel are the definition of brain food! Oily fish contains particular types of unsaturated fats called essential fatty acids - they are essential because your brain needs them for healthy function and the body cannot form them itself. Two types of essential fatty acids within the omega-3 family are called EPA and DHA which form cell membranes, support cell signalling and reduce inflammation.
All fruits and vegetables are incredible in their own right and a good variety of different fruits and vegetables should definitely be encouraged. But leafy vegetables have their own brain boosting benefits because they contain bio-active nutrients which are essential for the brain including beta carotene, folate, vitamin K, lutein, magnesium, potassium just to name a few!
Nuts and seeds contain a different sort of essential fatty acid called ALA which boosts brain health and also are good sources of polyphenols which are digested by the gut microbiomes and release phenolic acids that protect the brain by reducing inflammation and oxidation. They also contain vitamin E which have been linked to better memory function.
Caffeine, in those who can tolerate it, doesn’t present a brain health risk and instead boosts cognitive performance and even reduces the risk of dementia. Although, caffeine can impact our sleep and increase anxiety symptoms so experiment and find what works for you. Most people find they can tolerate 2-3 cups of coffee per day and that avoiding caffeinated drinks from 2pm tends to work well in terms of sleep quality and quantity. What we don’t want is the classic cycle of staying up too late because you can’t sleep due to caffeine intake and then spending the next day using caffeine as a crutch to get you through.
A Major Mechanism: The Gut-Brain Axis
One of the major ways food impacts our mood is via the Gut-Brain Axis. This is a constant two-way communication between the gastrointestinal tract and the brain. Although there is a lot more research needed, there is promising evidence that the gut microbiome i.e. the microbes in our gut, can influence this communication pathway.
Our gut microbiome is made up of a variety of bacteria, fungi and viruses which form a complex ecosystem. There is a link between gut microbiome disturbances and stress, anxiety and depression. Our microbiome is influenced by non-modifiable factors such as genetics but also modifiable factors such as diet. Ideally, we want as diverse of a gut microbiome as possible to balance blood sugar, reduce blood fats, regulate appetite, facilitate communication with the brain and protect us from disease.
To cultivate a healthy gut microbiome we need to boost our prebiotic intake. Prebiotics consist of fibre and resistant starch and are the ‘food’ for our microbiome. A wide variety of fibres are needed to cater to all of our different microbial species. Try swapping white bread, pasta or rice to their wholegrain or wholewheat variety.
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