The link between food and mood is a highly discussed topic. From a scientific perspective, strong evidence sits behind the negative moods associated with high fat & high sugar foods.
Furthermore, deficiencies of specific minerals and vitamins can affect tiredness levels and contribute to low moods. The vigorous evidence that is required to clinically recommend specific foods to support good mood is still underway, but significant studies have already been published, one of which is the well-known SMILES study. Although science is the backbone of public health messaging, perhaps on occasion concrete scientific evidence is not required to support the well-known feeling that some foods make us feel good and others don’t! Let’s take a closer look at both the science and general knowledge around food and mood.
Gut-brain axis
Our bodies have a large nervous system, one branch of which is known as the enteric nervous system which resides in our gut. Therefore, whatever effects our gut also affect our brain and may affect our mood. Furthermore, the microbes (bacteria, fungi + yeast) that live in our guts help produce hormones, chemical messengers in the body, which directly control our emotions. In fact, 90% of the ‘happy hormone’ serotonin is produced by gut bacteria! Therefore, the gut is often referred to as our second brain.
To support our gut microbes, it is important to eat plenty of high fibre foods like vegetables and wholegrain bread and other specific foods like yoghurt and avocados. See our blog on The Gut Microbiome to learn more!
Key Micronutrients & their Functions
Some Population Groups need to take Supplements
| Who | Nutrient | Reason |
| Vegans | B12 | B12 comes from only animal-derived sources |
| Pregnant women | Folic acid | Insufficiency may result in spine defect in babies |
| UK population October-April & post-menopausal women | Vitamin D | Vitamin D is primarily synthesized using UV from the sun which is not potent enough in this timeframe |
| Anaemia diagnosis | Iron | Anaemia is an iron deficiency |
The Mediterranean diet & The SMILES TRIAL (Supporting the Modification of lifestyle In Lowered Emotional States)
A famous study done in 2017 is the SMILES trial that examined the link between depression and treatment styles, including dietary changes. Participants who were struggling with diagnosed depression all took part in implementing more healthy choices with their diet – typically following the principles of the Mediterranean diet, as discussed above. To quote the paper ‘these results provide preliminary … evidence for dietary improvement as an efficacious treatment strategy for treating major depressive episodes.’ More robust studies are required to back this hypothesis with further evidence. However, several studies with valid variables and weight have shown that consuming a Mediterranean style diet over the course of life reduces both mortality and morbidity. On the other hand, some studies show that consuming a Western diet – a diet higher in processed foods and a lack of fruit, vegetables and fibre is one of the main causes of the current Western obesity epidemic.
What specific foods should I include in the diet to support my mental wellbeing?
No. 1 Rule – consume a variety of fruit and veggies, to help ensure plenty of minerals and vitamins are obtained.
Foods essential for mental wellbeing
| Food | Amount | Reason |
| Fish | 1 oily fish, 1 other fish / week | Omegas – Brain health |
| Nuts & Seeds | Handful / day | Microbiome + fibre |
| Extra Virgin Olive Oil | 60ml / day | Omegas – Brain health |
| Berries | Handful / day | Polyphenols |
| Wholegrains | 3 palmfuls / day | Ideal energy source + fibre |
| Green Leafy Veg | >1 Handful / day | Polyphenols |
Fun fact: the body stores two years worth of Vitamin B12 – thus if you are newly vegan and have consumed sufficient animal-derived foods such as meat and dairy in the past it is likely that B12 supplementation is not strictly necessary until two years have passed.
Low mood & the Glycemic Index
The Glycemic index refers to the value of food which correlates to how quickly or slowly it alters blood sugar levels. High sugar foods are known as quick release foods as they spike the blood sugar quickly before dramatically dropping, whereas lower sugar (and likely higher fibre + protein) foods are known as slow-release foods as they lead to a more steady incline, followed by a slower decline in blood sugar levels.
For example, if you ate a piece of chocolate cake it would lead to a spike in blood sugar levels. As a result, not long after eating this type of food, it is likely that your blood sugar levels would drop sharply resulting in a slump. In fact, the crash in energy after a ‘quick release’ food is part of their addictive qualities – you may then reach for another slice of cake. If, however, you consume slow-release energy foods such as starchy carbs like wholegrain rice or pasta and combine these with protein containing foods, blood sugar levels would be less varied and prevent a crash in energy.
High-sugar high-fat foods also lead to the release of the happy hormone serotonin. However, this is short-lived and the long-term consequence of a diet containing a high quantity of these types of food is likely to be quite the opposite, resulting in a low mood, irritability as well as weight gain.
Balance
Much like many things in life what we eat is all about balance. Sometimes it’s more than just food, it is a celebration, a meaningful moment with food at the centre – perhaps the end of Ramadan, Christmas day or a Birthday. On occasions such as these, simply be present and enjoy the food as part of the sensory experience.
If you enjoyed this blog or learnt something new, please do share it on your social media of choice or perhaps send it to a specific friend via email.
Get in touch for a consultation with one of our Registered Dietitians if you would like personalised advice on how to increase your mental wellbeing state.
By Grace Arrowsmith, dietetic student. Reviewed by Reema Patel, Registered Dietitian, MSc
References
SMILES Trial – 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
Diet Pyramid – Merra G, Noce A, Marrone G, Cintoni M, Tarsitano MG, Capacci A, De Lorenzo A. Influence of Mediterranean Diet on Human Gut Microbiota. Nutrients. 2021; 13(1):7. https://doi.org/10.3390/nu13010007
