How your diet affects your mental health – and what you can do about it

Nutritionist Kimberley Neve explains why our diet affects our emotional wellbeing, and how you can eat for better mental health.

It’s Blue Monday – claimed to be the most depressing day of any year. After all that 2020 brought and yet another national lockdown, it’s going to be extra tough this year.

In England alone, one in four people will experience a mental health problem of some kind, although that has appeared to increase as a result of the pandemic.

As a nutritionist, it’s clear that there’s a link between mental health and diet. Comfort eating is a common response to stress or feeling low, and eating disorders are very tightly intertwined with mental health issues. The question is: can it work the other way? Can what we eat impact how we feel in general?

Recent research says it can: a healthy diet has been shown to reduce symptoms of depression, and an unhealthy one is associated with a higher risk of depression. Scientists are still trying to answer the questions of why and how, so there’s a lot we don’t know, but read on to find out what they think is going on and how you can potentially shift your own mental health.

Note: this is not to say that changing your diet will cure depression. Depression, anxiety and related disorders need to be taken very seriously, and you should always seek help from a mental health professional if you’re struggling (I’ve added some links at the bottom that should help). Diet is just one factor of many that might help improve how you feel.

What links diet and the brain? 

It’s quite complicated, but two key links between what you eat and how you feel are inflammation and the gut microbiota.

1) Inflammation 

Inflammation is a normal response to fighting infection, but long-term, this can be harmful for the body.

Long-term inflammation, or chronic inflammation, has been associated with depressionInflammation has an effect on how our neurotransmitters work, such as dopamine and serotonin, which are known to be involved in our mood regulation. It can also affect how we respond to stressful situations.

One cause of chronic inflammation is a typical ‘Western’ diet– a diet containing a lot of foods that are high in fat and/or sugar (sweets, biscuits, crisps, chocolate, takeaways and fast food). 

At the same time, there are also foods that are associated with reduced inflammation and improved mental health. Foods that contain compounds called polyphenols, which are micronutrients found in plant-based foods, are anti-inflammatory and seem to be linked to reduced rates of depression, although the research in this area is limited.

Polyphenols are found in various fruits and vegetables, in particular berries and spinach, as well as nuts, beans and dark chocolate.

2) The gut microbiota 

This is the name for all the tiny microorganisms living in our gut. They’re responsible for many important functions in the body – not just digestion – including immune function and how we respond to stress.

Despite the physical distance and completely different functions, there is a connection between the gut and your brain called the gut-brain axis. It’s like a path that your gut microbiota uses to communicate directly with your brain using chemicals released into the blood.

It works both ways, so emotions from the brain can affect your gut, and the activity of the gut can affect mood and behaviour. It’s why you might need a pee before an exam because you feel nervous, or why you might feel bloated or have a stomach ache when you’re stressed.

It’s also the reason for feeling butterflies in your tummy when you first date that special someone!

Different gut bacteria have been shown to increase levels of certain neurotransmitters directly linked to our mood, such as dopamine and serotonin. Serotonin in particular is often referred to as the ‘happy hormone’ – more serotonin in your body means more happiness. As a result, having a diet that is gut-friendly has been associated with more positive mental health.

How can you eat for better mental health?

Some important studies have shown that a shift towards a healthier diet can reduce symptoms of depression. More research is needed to know exactly what it is in foods that can improve mental health, but in a meta-analysis of relevant studies that included 16 studies and a total of 45,826 participants, ‘healthy’ meant: 

  • Less ‘junk’ food- high in fat and/or sugar (pastries, white bread, many breakfast cereals, etc.)
  • More foods high in fibre, vitamins and minerals (fruit, vegetables, grains, nuts, seeds, legumes and beans).

Having a range of foods that are high in fibre makes your diet more gut-friendly, as the fibre feeds the gut bacteria and allows them to thrive.

Vitamins (e.g.,B vitamins), fatty acids (e.g.,omega 3 fatty acids)andminerals (e.g., zinc, magnesium) may also be protective from mental illness; however, more research is needed for individual nutrients.

The key takeaway here is, as is often the case with nutrition, a balanced diet that has more healthy foods than unhealthy ones. What I’d advise for potential mental health benefits is a focus on increasing fibre intake from a range of sources to help the gut microbiota thrive.

Do this slowly, as adding a lot more fibre too quickly can cause bloating and discomfort. Simple ways include adding lentils to a soup or beans to a slow-cooker dish, or keeping the skin on your vegetables where possible. 

For more help with improving your gut health, or other nutrition concerns, Kimberley offers Nutrition Check-Ins; one-off sessions to discuss your diet and a personalised plan for improving your nutritional health.

If you’re struggling with mental health, here are some links for help: