What causes chronic inflammation and 5 science-backed ways to tackle it

The impact of chronic inflammation on our bodies as we age (also known as 'inflammaging') is increasingly being talked about.

It's been linked to a range of illnesses including some of biggest killers both in the UK and globally - the World Health Organization (WHO) ranks chronic diseases as the greatest threat to human health, with 3 in 5 people dying of chronic inflammatory diseases worldwide.

But what do you need to know about it and do trendy 'anti-inflammatory diets' really minimise the risk? 

We asked inflammation experts including Professor Asif Iqbal, Professor Janet Lord and Professor Lettie Bishop about the science behind chronic inflammation, and what lifestyle changes you can make to help keep it at bay.

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What is chronic inflammation and why does it matter?

Inflammation isn't universally bad, it plays an important role in our bodies' natural healing process for acute injuries such as a sprain, insect bite or sunburn - typically causing swelling, redness and pain.

Asif Iqbal, professor of inflammation biology at the University of Birmingham, tells us: 'People often think of inflammation as a bad thing, but it's a host response that's critical to the normal function of the immune system. If you don't have inflammation, you're going to have major issues.'

However, the problems come when this system gets dysregulated, which can lead to chronic inflammation. This has increasingly been linked to a number of major diseases, from heart disease and diabetes to some cancers.

Acute inflammation typically lasts a matter of days or weeks. Chronic inflammation, on the other hand, can build up gradually over time - and you may be unaware of it.

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Symptoms are diverse and often non-specific, encompassing fatigue, joint and chest pain, frequent infections, poor wound healing, low mood and gastrointestinal issues.

Lettie Bishop, professor of exercise immunology at Loughborough University, says: 'By the time you are being investigated for the existence of symptoms that indicate chronic inflammation, this ''dripping tap'' will have been on for a period of months or even years.'

Why chronic inflammation is on the rise

As the population is living longer, this kind of 'inflammaging' is a significant contributor to the rise in inflammatory conditions and associated diseases, and lifestyle factors have an impact too.

‘Fat tissue, not being physically active enough and having an immune system that doesn’t remove [old] senescent cells are three of the big causes of inflammation as we age', says Prof Lord.

However, this isn’t the entire picture: inflammatory conditions are on the rise in younger people, too. Experts say changes in wider societal habits, such as reduced physical activity, poor diet and being overweight, are key drivers across all ages. 

‘Although baseline inflammation levels increase with age, there are situations where it can be accelerated’, says Prof Bishop. 'Levels of inflammation in a younger person with obesity are similar to someone much older who doesn’t have obesity, so what you’re effectively seeing is accelerated ageing.’

5 causes of chronic inflammation

A number of lifestyle factors can cause or contribute to chronic inflammation. These include:

Stress 

Chronic stress can cause sustained low-grade brain inflammation (neuroinflammation), which is linked to mood disorders, memory and cognitive dysfunction such as Alzheimer’s disease, as well as heart disease.

Obesity

Being overweight or obese can cause an increase in inflammatory immune cells linked to cardiovascular disease and can lead to chronic metabolic inflammation (metaflammation) that contributes to Type 2 diabetes.

Poor diet

A diet high in sugar, saturated fat and refined carbohydrates can produce inflammatory markers. Foods that disrupt the gut microbiome can lead to inflammation, too.  

Sleep deprivation 

Chronic insomnia, nightshift work and other sustained sleep and circadian rhythm disorders (SCRD) can raise inflammation levels. Aim for at least seven hours of sleep.

Smoking and air pollution

Smoking creates chronic inflammation of the vascular system. According to the WHO, exposure to air pollution such as dust, fumes or smoke leads to inflammation and oxidative stress.

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5 ways to help reduce chronic inflammation

Some inflammation is an inevitable part of ageing, but scientific evidence suggests there are ways to help slow some of it down. 

Many of the things considered beneficial for a healthy lifestyle will also help with inflammation. Here's what the experts told us can help:

Eat more anti-inflammatory foods

Opting for a Mediterranean-style diet may help to reduce chronic inflammation. So, aim to eat more oily fish, fruit and vegetables (including berries), wholegrains, nuts, seeds and legumes. 

Use olive oil or other oils/products rich in monounsaturated fats, and choose chicken or lean cuts if eating meat.

Processed meats and red meat should be avoided or eaten sparingly, and the same goes for processed and sugary food and drinks, refined carbohydrates and foods high in saturated fats. 

Limit your alcohol intake, too. 

Move more - and more often

‘Sitting is the new smoking’ our experts said. Prolonged inactivity increases inflammatory markers, while exercise has an anti-inflammatory effect.

Janet Lord, emeritus professor of immune cell biology at the University of Birmingham, recommends using a sit/stand desk if you're working and aiming to get up and move about for around 10 minutes every hour. This can be as simple as getting up to make a drink, putting a load of washing on or going for a short walk.

Of course, for some people with reduced mobility or other health issues, this can be a challenge, but every little helps. Prof Bishop says to try and just 'move more, whether that's parking 10 minutes further away or simply getting up and moving around the house, you've got to start somewhere.' 

So start small with what's manageable for you. Regular movement throughout the day is what matters, it doesn't have to be intense exercise.

Look after your teeth and gums

Growing evidence links severe gum infection (periodontitis) to chronic inflammatory conditions, including Type 2 diabetes, cardiovascular disease and strokes. 

Inflammation from the infected oral cavity can travel in the bloodstream all around the body so regular brushing and flossing is a really important habit to stick to.

Need a helping hand? See our reviews of the best electric toothbrushes and air flossers, plus how to choose the best toothpaste.

Get warm (or cold, possibly)

Increasing your body temperature through ‘passive heating’, such as a sauna or hot bath, has been shown to help inflammation. Studies show it leads to an initial release of inflammatory markers followed by a longer-lasting anti-inflammatory response. 

What about the craze for ice baths and cold swimming? The science isn't quite so clear-cut on this one. A 2024 systematic review found that ice baths raised adrenaline, which can indirectly reduce inflammation, although further research is needed before it can be recommended to those with inflammatory disorders.

Keen on the sauna trend? See our guide to buying a home sauna for tips and advice, plus popular models and prices.

Try intermittent fasting

Intermittent fasting may help to reduce inflammatory markers and increase autophagy, a process where damaged cell parts are gobbled up for energy instead of causing inflammation. 

A small 2021 randomised controlled trial found that eating within an eight-hour window for 12 months (plus resistance training) significantly improved inflammatory markers.

However, more research is needed, and fasting isn’t suitable for everyone, so always check with your doctor if you're considering it.

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What about anti-inflammation supplements?

Only one nutrient has proven effectiveness as an anti-inflammatory, according to the UK Nutrition and Health Claims Register, and that’s vitamin D, where deficiency leads to higher levels of inflammatory biomarkers.

The anti-inflammatory properties of various alternative remedies, including some herbs and spices, have been the subject of much research, including a 2024 study looking at over-the-counter anti-inflammatory supplements for rheumatoid arthritis. 

But while some show potentially promising anti-inflammatory effects, there were concerns about consistency and quality, lack of standardised dosages and unclear interactions with conventional medications.

UK law forbids supplements from being called ‘anti-inflammatory’ or making claims about disease treatment or prevention, so packaging should never claim this.

Supplements you do and don't need - see our expert guide to what is really necessary and who for

Our inflammation research

For our investigation into inflammation, Which? researcher Martha Roberts interviewed leading experts for their insights, as well as reading scores of academic papers for evidence-based information. All our investigative articles are checked by a second senior researcher as part of our independent processes.

Martha is an award-winning senior health writer with 25 years of experience writing about health and wellbeing topics for national newspapers, magazines and websites, and for the charity sector. 

In her five years at Which? she has investigated popular subjects on health, food and parenting, including night-driving glasses, indigestion remedies and what you need to know about retinol, to help you cut through the hype and make buying decisions with confidence.

Inflammation experts Martha spoke to for this article included:

• Asif Iqbal, professor of inflammation biology at the University of Birmingham's department of cardiovascular sciences. Prof Iqbal has been studying the role of inflammation in cardiovascular diseases and other chronic inflammatory pathologies. 
• Janet Lord, emeritus professor of immune cell biology at the University of Birmingham research labs department of inflammation and ageing. Prof Lord's research has looked at how ageing affects immune function and inflammation resolution in older adults, as well as the link between chronic systemic inflammation and physical frailty in older people.
• Lettie Bishop, professor of exercise immunology at Loughborough University's school of sport, exercise and health sciences. Prof Bishop's research interests span the effects of immunity, inflammation and infection on both the general population and those with specific long-term conditions.