How Ultra-Processed Food Affects Mental Health: A Psychiatrist Explains the Link

By Dr James Woolley, Consultant Psychiatrist at Schoen Clinic Chelsea.

As a Consultant Psychiatrist, I often discuss the cornerstones of good mental health with my patients: therapy, medication where appropriate, exercise, and strong social connections. However, a growing and compelling area of research is shining a light on another powerful factor we may be overlooking: our diet.

Recent studies and headlines are increasingly pointing towards a significant link between ultra-processed food (UPFs) and mental health conditions such as depression, anxiety, and low mood. While the idea that food affects how we feel isn’t new, the emerging science is painting a much clearer picture.

We’ve all reached for a biscuit or a bag of crisps when feeling low, it’s often called ‘comfort eating’. But what if that short-term comfort is contributing to a longer-term problem?

What Are Ultra-Processed Foods?

While there’s no single, universal definition of ultra-processed foods, most experts agree they go far beyond basic food processing. UPFs are industrial formulations typically made with five or more ingredients, including additives you wouldn’t use at home, like preservatives, emulsifiers, sweeteners, and artificial colours or flavours.

These foods include:

• Fizzy drinks and sweetened juices

• Sugary breakfast cereals

• Many packaged breads

• Mass-produced ready meals

• Crisps, biscuits, and other packaged snacks

They're engineered to be hyper-palatable and convenient, but they often lack essential nutrients our brains need to thrive.

New Research Linking Food and Mental Health

In 2024, a large-scale review published in The BMJ analysed data from nearly 10 million people and found direct associations between high UPF consumption and an increased risk of mental health issues, including depression and anxiety disorders.

This adds to a growing body of research suggesting that what we eat has a profound impact on brain health, emotional regulation, and psychological resilience. While the evidence doesn’t yet prove causation, the strength of the link is becoming too significant to ignore.

3 Ways Diet Affects Mental Health

Researchers are exploring several key biological mechanisms through which diet may influence mental wellbeing:

1. The Gut-Brain Axis

Our gut is home to trillions of microbes, known collectively as the gut microbiome, that communicate directly with the brain. In fact, over 90% of serotonin, a neurotransmitter involved in mood regulation, is made in the gut.

Diets high in ultra-processed foods may disrupt this delicate microbial balance, which in turn could contribute to low mood, anxiety, or changes in emotional resilience.

2. Inflammation and Depression

UPFs are known to promote chronic low-grade inflammation throughout the body. This type of systemic inflammation has been increasingly linked to depressive symptoms and cognitive decline.

A poor diet may not only affect the body but may also create a pro-inflammatory environment in the brain.

3. Nutrient Deficiencies

UPFs are often low in essential nutrients such as omega-3 fatty acids, B vitamins, zinc, magnesium, and other micronutrients needed for healthy brain function. Over time, this can leave the brain under-fuelled, affecting everything from concentration to emotional regulation.

A Psychiatrist’s Advice: Small, Sustainable Changes

This article isn’t here to create fear around food or suggest a one-size-fits-all dietary overhaul. No food is inherently “bad”, and being overly restrictive can do more harm than good, especially for those with a history of disordered eating.

Instead, the goal is awareness. By making small, sustainable swaps, we can give our minds better fuel to function at their best.

Try asking yourself:

• Could I replace a sugary breakfast cereal with porridge and berries?

• Instead of a fizzy drink, would sparkling water with fresh lime hit the spot?

• Can I cook a simple homemade meal one more time this week?

These changes don’t need to be perfect. What matters is progress, not perfection.

Diet: A Key Pillar of Mental Health

Food is not a cure-all for mental illness. It should never replace professional support such as psychiatric care, therapy or medication. However, there is growing evidence that nutrition plays a central role in mental wellbeing, and it deserves more attention.

At Schoen Clinic Chelsea, our clinicians take a holistic, evidence-informed approach to mental health treatment. We encourage patients to consider how sleep, activity, relationships, and nutrition all interact to support recovery.

Caring for our minds means caring for our bodies, and what we put on our plates can be a good place to start.

Further Reading

• The BMJ – Ultra-processed food exposure and mental health outcomes: Read the study

• The Guardian – Ultra-processed foods linked to 32 health issues: Read article

• BBC Future – How gut bacteria affect your brain: Read more

• MIND Charity – Food and mood: Support resources

• NHS Eatwell Guide – Healthy eating basics

Need Support with Your Mental Health?

If you're struggling with low mood, anxiety, or want to explore holistic mental health support, our team at Schoen Clinic Chelsea includes experienced psychiatrists, therapists and dietitians who can help.

Explore our outpatient services or book an assessment today.

About the Author: Dr James Woolley is a Consultant Psychiatrist at Schoen Clinic Chelsea with a special interest in complex trauma, anxiety disorders and emerging treatments for treatment-resistant mental health conditions.