We know that what we eat impacts our health. But did you know that our food choices may impact our mental health?
Sadly, there is no one size fits all approach to dealing with our mental health. Multiple factors play into it including our individual history, psychological state, genetics, food consumption, culture, environment, and lifestyle (1).
Depression is one of the most prevalent disorders worldwide. Mental symptoms include low mood and low self-esteem. Physical symptoms include changes to sleep cycle and changes to appetite (2).
What Does This Have To Do With The Brain?
In the brain, the hippocampus is involved in mood regulation and memory. Mood regulation is influenced by different neurochemical connections in the brain. These different neurochemical connections involve nutrients from our food, in the production of neurotransmitters in the brain (3).
There are hormones that act as neurotransmitters. Serotonin is our ‘happy’ hormone that contributes to good mood. Dopamine is a reward and motivation hormone that produces feelings of pleasure. Y-aminobutyric acid (GABA) is a neurotransmitter that plays a role in calming and slowing down brain activity. Deficiencies in serotonin, dopamine, and GABA are often associated with depression (5).
The ‘inflammation theory of depression’ comes from the consistent relationship between inflammation and depression. This theory explores the involvement of inflammation contributing to severe depression symptoms. One cause of inflammation is a poor diet which is associated with high levels of inflammatory cytokines released by immune cells (15).
What foods should I be eating? 7 Food Groups To Become Aware Of
Developing evidence suggests that diets characterised by high consumption of fruit, vegetables, wholegrains, and fish are associated with lower risk of depression (4).
The UK Eatwell guide is evidence-based and provides a visual representation of a healthy balanced diet. Having regular meals, eating a good amount of unsaturated fat, choosing wholegrain options, including fruit and vegetables, varying protein sources, and staying hydrated whilst limiting caffeinated drinks and alcohol is all recommended for a healthy diet (7).
1. Fruit and Vegetables
These contain a range of antioxidants, vitamins, and minerals that have neuroprotective properties that are believed to protect against depression (8). Ones to consider include:
- Vitamin A (beta-carotene): Carrots, Mangos, Bell Peppers, and Sweet potato.
- Vitamin B: Dried fruits, Mushrooms, Tomatoes, Broccoli, and Oranges.
- Vitamin C: Citrus fruits, Berries, and New Potatoes.
- Vitamin E: Vegetable oils and Dark leafy greens.
- Vitamin K: Spinach, Cabbage, Peas, and Cauliflower.
2. Nuts and seeds
These are rich in a-linolenic acid (ALA) and polyphenols which produce phenolic acids that reduce inflammation and oxidation, helping protect our brains. They help improve how brain cells communicate and promote neurogenesis (9). Plus, they contain selenium, vitamin E, and magnesium which all contribute to brain health.
They can be great as a snack (one-two tablespoons are a portion), there is a huge variety of nut butter available, and seeded wholemeal bread is great (plus provides a fiber boost).
Sources include almonds, cashews, peanuts, chia, flaxseeds, hemp, sesame, and sunflower (remember to choose unroasted and unsalted).
3. Oily fish
Oily fish are a good source of omega-3 fatty acids (unsaturated fats). These must be obtained through our diet. They are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and lastly a-linolenic acid (ALA). These fats form part of the cell membranes in the brain, supports brain functions, enhanced dopamine and serotonin systems, and reduced inflammation in neurons (9).
A good way to remember which oily fish count is ‘SMASH’– Salmon, Mackerel, Anchovies, Sardines, and Herring.
If you do not consume fish, then an algae-based omega-3 supplement is recommended.
Protein sources include meat, poultry, fish, legumes, pulses, and dairy products. Protein is made up of amino acids, and a high-quality diet contains all the essential amino acids (6).
Neurotransmitters in the brain are made from some amino acids. Neurotransmitter Tryptophan is converted into serotonin in the brain (6). Neurotransmitters dopamine and norepinephrine are produced by the tyrosine amino acid. After a protein-rich meal, the levels of tyrosine rise which promotes the levels of dopamine and norepinephrine to rise, increasing alertness and mental awareness (10).
Carbohydrates are an important macronutrient as this is the body’s preferred source of energy (6).
Carbohydrate intake can be used to modify the uptake of tryptophan into the brain due to the release of insulin. When we consume a high carbohydrate diet, insulin is released. This allows tryptophan to have easier access to the transport molecule, increasing serotonin levels, leading to improved mood. (16).
Choose wholegrains where possible and eat a variety of beans, alliums, and legumes. This provides essential fiber to feed our gut microbiome. This is to support the ‘gut-brain axis’ which supports our immune system and brain health (18).
It is advised not to consume tryptophan supplements because of the potential to cause serotonin toxicity when combined with antidepressant drugs, and there are many side effects such as diarrhea, blurred vision, and nausea (17).
Water is essential for life. Hydration levels play a role in cognitive brain function. Studies suggest that dehydration can negatively impact cognitive abilities in humans and sustained dehydration is associated with poor health (12). Even mild dehydration is known to reduce concentration, alertness, short term memory loss and alter mood (13).
We need to aim for 2 litres a day, and more when it is hot. Using our urine is a good indicator of our hydration levels (we should be aiming for clear/pale).
Alcohol can have an impact on our serotonin levels. When we drink, serotonin may contribute to the rewarding and intoxicating effects because of the feel-good factor. However, alcohol intake hinders the body’s ability to use serotonin, with both short and long-term alcohol exposure. This is believed to impact the serotonin receptors that convert the chemical signals into functional changes in the brain, thus influencing our mood (14).
Cracking Some ‘SMILES’– The Mediterranean ‘’Modimed’’ style diet (11).
The ‘supporting the modification of lifestyle in lowered emotional states’ (SMILES) trial is a randomised control trial investigating dietary improvement and depressive symptoms. 67 individuals with clinical depression were recruited and randomly assigned to a dietary support group (received support from registered dietitian) or a social support group (met with research assistant- no dietary support) over a 12 week period.
Participants were only asked to adjust their diets. The dietary support group was supported in consuming Mediterranean style diet. This involved reducing intakes of crisps, sweets, desserts, fast foods, and packaged foods. Whilst increasing intakes of whole foods, whole grains, fruits and vegetables, fish, lean red meat, beans, legumes, olive oil, and nuts.
The diet was designed to be achievable, affordable and sustainable long term.
The researchers found that as people adhered to the dietary improvements, their moods improved alongside.
Overall, following a healthy diet is beneficial for our brain health and in turn our mood. Ensuring that the diet is sustainable and flexible with adequate calories and hydration that can be enjoyed is more important than following an inflexible diet.
This is not an extensive list and does not take away from registered health professionals’ advice. Please speak to a registered nutritionist or dietitian before making any changes to your diet.
Francesca Vuolo is a recent graduate with a accredited BSc in Nutrition, currently studying for her MSc in Nutrition and Behaviour. She has a keen interest in nutritional psychology, mental health, and health education.