The Link Between your Belly and Brain

How Diet can affect your Mood

Originally published on: September 21st, 2021.

How your Diet can affect Anxiety and Depression

The gut has long been called ‘the second brain’ so it stands to reason that there is a relationship between what you eat and your mental health. Nutritional psychiatry has been a growing area of research in recent years, with most studies focusing on the effects of different foods on the brain and whether certain diets can help improve our mental wellbeing.

A recent study undertaken by Joseph Firth, a research fellow at Manchester University suggests that “poor nutrition may be a causal factor in the experience of low mood and that improving diet may help to protect not only the physical health but also the mental health of the population₁.” 

The study examines a Western diet (associated with being high in processed foods and sugar) versus a Mediterranean diet and how these affect our glycaemia, immune system and levels of inflammation within our body and the link between our mental health.

It has been observed that eating a Mediterranean diet that is high in fruits, vegetables, legumes, with a moderate amount of poultry, eggs and dairy and low consumption of red meat is associated with a reduced risk of depression₂.

Belly and Brain - Bladder & Bowel Community
Eating a Mediterranean diet is associated with a reduced risk of depression

The link between Inflammation and our Mental Wellbeing

One thought process for this is that a Western diet high in refined sugars and calories can stimulate immune activation and high inflammatory markers and this immune response can have a detrimental effect on our brain health, including our cognition, and our hippocampus (an area of the brain responsible for our mood and cognition). By following a Mediterranean diet that is lower in saturated fats and refined sugars and processed foods, we can lower inflammation in the body and possibly reduce the risk of clinical depression₁.

It’s important to note that more research is needed to firmly link the reduction of inflammation in the body to our mental health but it is certainly a consideration.

How our Gut can Increase Serotonin Levels

What we eat can affect the function of our brain. Our gut microbiome (the trillions of bacteria  that naturally live within our gut) helps to determine how well we absorb nutrients from our food, activate neural pathways between our gut and our brain and regulate how much serotonin we produce₃. Serotonin is a key hormone in our body that helps us to regulate our sleep and balance our mood, but has also been linked with irritable bowel syndrome. Serotonin is found in both our brain and our gut and low levels of this hormone can lead to anxiety and depression.

Eating foods that nourish our gut microbiome can help to regulate our serotonin and therefore regulate our mood. Foods that are rich in fibre such as wholegrains, beans, legumes, fruits and vegetables are good for our gut bacteria. Foods high in sugar, additives and preservatives can disrupt our gut microbiome and the levels of serotonin in our body.

What should we eat to regulate our mood?

  • Eat regular meals – eating small and regular meals can help provide our brains with a steady stream of glucose, which provides fuel to our brains
  • Increase whole grains, fruits and vegetable – these foods are high in B vitamins and folate which can help to manage depression
  • Include oily fish as part of your diet – some research has shown that omega-3 oils can help with depression. Oily fish includes salmon, mackerel, sardines, pilchards and trout
  • Stay well hydrated – aim to drink around 2 litres of water a day. Dehydration can lead to headaches and cause irritability 
  • Limit your alcohol intake – alcohol can cause dehydration and can strip you of vital vitamins. Alcohol itself is a depressant and can make depression and anxiety worse.

What is a Mediterranean diet?

As mentioned studies are showing that following a healthy Mediterranean diet is associated with a reduced risk of depression. Food groups include

  • Starchy foods such as bread and pasta
  • Lots of fruit, vegetables, legumes and beans
  • Moderate amount of poultry, eggs and dairy products
  • Limited amount of red meat

To summarise, we are in early research as to whether there is a link between what we eat and how we feel but there is certainly information to suggest that a healthy diet and a well hydrated body can help to regulate our mood.


₁BMJ 2020;369:m2382

Lassale C, Batty GD, Baghdadli A, et al. Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Mol Psychiatry2019;24:965-86. doi:10.1038/s41380-018-0237-8 pmid:30254236