Inflammation and mental health: what it is, why it matters and how to reduce it

Inflammation has become widely discussed in the media and on social platforms. It’s often described as something harmful, something we should try to “reduce” or “fight.” But inflammation is not inherently bad. In fact, it’s a natural and essential part of how the body protects and repairs itself.

Problems arise when inflammation becomes persistent. This chronic, low-level inflammation has been linked to a range of physical health conditions, and growing research suggests it may also play a role in mental health, particularly depression.

But what does inflammation actually mean, and how does it affect our mental health? In this blog, we explore what inflammation is, how it affects mental health, and evidence-based ways to help reduce chronic inflammation to support mental wellbeing.

What is inflammation?

Inflammation is the body’s built-in defence system. It’s how your immune system responds to injury, infection or anything it sees as a threat. While often talked about as something to ‘avoid’, inflammation is vital – it protects the body and helps repair damage.

Problems arise when inflammation becomes long-term. Chronic inflammation has been linked to mental ill health, influencing mood, energy, motivation and even how the brain responds to treatment. It’s important to remember that it is just one factor; mental health is shaped by a mix of biological, psychological and social influences.
When something goes wrong, such as a cut, a virus, or damaged tissue, the immune system sends signals to increase blood flow and immune activity in that area. This helps fight infection, remove damaged cells, and start the healing process. Inflammation itself isn’t harmful – in fact, we couldn’t survive without it.

There are two main types of inflammation:

Acute inflammation, which is short-term and protective
Chronic inflammation, which is long-lasting and potentially harmful

Understanding the difference between the two is key to understanding how inflammation affects mental health.

Acute vs chronic inflammation: what’s the difference?

Acute inflammation

Acute inflammation is the body’s immediate, short-term response to a problem. It usually lasts hours or days and switches off once healing has begun.
Common examples include:

Swelling, redness or pain after an injury
A fever when fighting an infection
Feeling tired or run-down while unwell

This type of inflammation is necessary and allows the body to repair itself.

Chronic inflammation
Chronic inflammation occurs when the immune system stays activated for long periods of time, sometimes months or even years. Unlike acute inflammation, chronic inflammation is:

Low-level and ongoing
Often invisible, with no obvious symptoms
Able to affect multiple systems in the body, including the brain

Chronic inflammation can interfere with normal biological processes and affect healthy tissue. Chronic inflammation is influenced by long-term stress, poor sleep, unbalanced diet, gut health disruption, physical inactivity, chronic illness and environmental factors. This is the type of inflammation most strongly linked to depression and other mental health conditions.

How inflammation affects mental health

There is now substantial evidence linking chronic inflammation and depression. Associations have also been found with anxiety and bipolar disorder. Large population studies show that people living with chronic inflammatory conditions are significantly more likely to experience mental health difficulties. Importantly, this relationship works both ways:

Poor mental health can increase inflammation through prolonged stress responses
Chronic inflammation can alter brain function and worsen mental health symptoms

How inflammation affects the brain

Inflammatory signals, called cytokines, can influence brain function through communication between the immune system and the brain. Chronic inflammation can:

Influence neurotransmitters such as serotonin and dopamine, which play key roles in regulating mood, motivation, and pleasure.
Activate stress pathways, including cortisol, keeping the body in a heightened stress state that can worsen anxiety and low mood
Reduce brain plasticity, the brain’s ability to form new connections, which can make learning, memory, and emotional resilience more difficult.
Alter motivation and reward systems, making it harder to feel pleasure, pursue goals, or stay engaged in activities. This can contribute to fatigue, lack of interest in hobbies and social withdrawal – symptoms commonly seen in depression.

Together, these changes may contribute to symptoms such as:

Persistent low mood
Fatigue
Brain fog
Reduced motivation
Social withdrawal

The “sickness response” and depression

When you have the flu, you probably feel tired, withdrawn and less interested in food or socialising. This is called the “sickness response”. It is a temporary behavioural shift triggered by inflammation. It helps the body conserve energy and focus on recovery. However, if inflammation remains elevated long term, elements of this sickness response can stay activated. The result can look very similar to depression, including low energy, reduced pleasure and difficulty concentrating.

The gut–brain–immune connection

A large proportion of immune activity occurs in the gut, making gut health central to inflammation regulation.

The gut microbiome helps:

Support a balanced immune system
Reduce chronic low-level inflammation
Produce compounds that support brain health

Disruptions to the gut microbiome – caused by stress, illness, diet, or environmental factors – can increase inflammation and affect mental wellbeing.

What does new research tell us?

Scientists are continuing to investigate whether inflammation increases the risk of developing depression, or whether it mainly worsens symptoms once depression is present. Evidence suggests both may occur. Importantly:

Not everyone with depression has elevated inflammation
Those who do may experience more fatigue and physical symptoms
Inflammation may influence how well some people respond to antidepressants

Researchers are now exploring more personalised approaches to treatment, where inflammation levels may help guide decisions. This doesn’t mean depression is caused by inflammation alone. Our mental health is influenced by many interconnected factors.

What can increase chronic inflammation?

Chronic inflammation tends to build up over time, influenced by a mix of lifestyle habits, stress and environmental factors.

Chronic stress

Long-term stress repeatedly triggers the body’s fight-or-flight response. When we face a threat, our body releases stress hormones like cortisol to help us react quickly. In short bursts, this system is protective and helps keep inflammation under control. But when stress is constant, day after day, the body can become less responsive to cortisol’s regulatory effects. This makes it harder to switch off inflammation, which can slowly build up over time. Over the long term, this low-level, persistent inflammation may contribute to both physical health problems and mental health challenges, including depression.

Poor sleep

Sleep is essential for keeping your immune system balanced and functioning properly. A few nights of poor sleep can temporarily increase inflammation. Over time, chronic sleep disruption can keep the immune system in a heightened state of activation. Poor sleep and depression often reinforce each other, potentially through inflammatory pathways.

Diet high in ultra-processed foods

Highly processed foods that are high in refined sugars, emulsifiers, unhealthy fats and low in fibre and micronutrients can:

Disrupt blood sugar regulation
Promote oxidative stress (cellular “wear and tear”) that can trigger inflammation
Reduce beneficial gut bacteria
Increase inflammatory signalling

Low intake of omega-3 fatty acids, found in oily fish, nuts and seeds, may also reduce the body’s ability to regulate inflammation effectively. Dietary patterns matter more than individual foods, and a consistently unbalanced diet may contribute to long-term immune activation. These factors often interact, meaning that small changes in several areas can have a combined positive effect.

Physical inactivity

Regular movement is one of the most effective ways to help keep inflammation in check. When you exercise, your muscles release molecules called myokines, which have anti-inflammatory effects throughout the body. Physical activity also improves how your body processes sugar, supports a balanced immune system, and helps maintain healthy circulation.

Without consistent movement, these protective benefits are lost, leaving the body more prone to chronic low-level inflammation. Even moderate, regular activity, such as walking, cycling, or gentle strength exercises, can make a meaningful difference over time.

Social factors

Social factors such as financial stress, social isolation and early-life adversity can also influence inflammatory pathways.

Environmental exposures

Some research suggests that air pollution, cigarette smoke, and other environmental toxins can increase inflammatory activity in the body. Tiny particles and chemicals in polluted air or smoke can enter the lungs and bloodstream, triggering the immune system to respond. Over time, repeated exposure can keep the immune system in a heightened state, contributing to chronic low-level inflammation that may affect overall health, including mental wellbeing.

What helps reduce inflammation?

Managing inflammation works best through steady, sustainable lifestyle choices rather than extreme or temporary measures.

Food and nutrition

Eat a wide variety of plant foods (beans, lentils, nuts, seeds, fruits, vegetables): Aim for 30 or more different plant foods each week – such as beans, lentils, nuts, seeds, fruits and vegetables. These foods contain vitamins, minerals and antioxidants that help calm your immune system and reduce inflammation. The fibre also feeds beneficial gut bacteria, which produce compounds that help regulate inflammation.
Include oily fish or other sources of omega-3 fats: Oily fish, such as mackerel and salmon, provide omega-3 fats (EPA and DHA), which are associated with anti-inflammatory effects. Plant sources such as flaxseed and chia provide ALA, another form of omega-3. These can support gut and overall health as part of a varied, fibre-rich diet that helps support lower chronic inflammation.
Add fermented foods where possible: Some fermented foods, such as live yogurt, kefir, sauerkraut and kimchi, can contain beneficial bacteria that support gut health. A balanced gut microbiome supports the immune system in responding appropriately, reducing unnecessary inflammatory responses.
Focus on dietary diversity: Eating a wide variety of whole, nutrient-rich foods maintains a diverse gut microbiome, which supports balanced immune responses and helps reduce inflammation.
Reduce intake of ultra-processed foods: Foods high in refined sugar, trans fats, and additives can activate the immune system and increase inflammation. They may also disrupt the gut lining, increasing gut wall permeability (sometimes referred to as “leaky gut” in popular discussions), allowing food and bacterial components to enter the bloodstream and trigger immune activation. Reducing consumption of ultra-processed foods can lower unnecessary inflammatory signals and support overall gut and immune health.

Movement

Regular physical activity: Regular physical activity helps regulate inflammation partly by improving how the body responds to stress hormones such as cortisol, and by promoting the release of anti-inflammatory molecules called myokines. Even moderate, consistent activity can reduce chronic low-level inflammation.
Consistency over intensity: Long-term, sustainable movement is more beneficial than sporadic high-intensity workouts, which can temporarily increase inflammation if overdone.

Stress and rest

Chronic stress management: Ongoing psychological stress activates the immune system and raises levels of pro-inflammatory molecules. Stress-reduction techniques like mindfulness, meditation, and deep breathing can lower inflammation by calming the stress response.
Good sleep and regular rest: Sleep helps regulate the release of hormones such as cortisol and melatonin, both of which influence inflammation. Adequate rest allows the body to repair tissue and reset immune function.

You don’t need to change everything at once. Small, consistent changes can make a meaningful difference over time.

Conclusion

Inflammation is a normal and essential bodily process. Problems arise when inflammation becomes chronic.

Mental health is closely linked to immune, gut, and physical health, so supporting the body as a whole can also support wellbeing. While inflammation is only one piece of the puzzle, consistent lifestyle habits, such as balanced nutrition, regular movement, good sleep, and stress management, can make a meaningful difference.

Small, manageable changes over time can help keep inflammation in check and support both body and mind.

Where to get help

If you need further advice on supporting yourself or a young person with their mental health, take a look at the services below that can help.

Papyrus

Offers confidential advice and support for young people struggling with suicidal thoughts, as well as family and friends; and information about how to make a safety plan.

Its helpline service – HOPELINE247 – is available to anybody under the age of 35 experiencing suicidal thoughts, or anybody concerned that a young person could be thinking of suicide.

Opening times:24/7 every day of the year
0800 068 4141
Text: 88247

Inflammation and mental health: what it is, why it matters and how to reduce it

What is inflammation?

Acute vs chronic inflammation: what’s the difference?

How inflammation affects mental health

What does new research tell us?

What can increase chronic inflammation?

What helps reduce inflammation?

Conclusion

Where to get help

Papyrus

Samaritans

Parenting Mental Health

Explore Our Publications

More from YPMH

About us

Donate

Fundraise

Collaborate with us

The need

Inflammation and mental health: what it is, why it matters and how to reduce it​

What is inflammation?

Acute vs chronic inflammation: what’s the difference?

How inflammation affects mental health

What does new research tell us?

What can increase chronic inflammation?

What helps reduce inflammation?

Conclusion

Where to get help

More from YPMH

Inflammation and mental health: what it is, why it matters and how to reduce it