The foods to eat to reduce inflammation — and those to avoid

Times

20 hours ago

Inflammation has been linked to the development of a host of life-threatening health conditions including heart disease, cancer, obesity, type 2 diabetes and dementia, and it plays a causal role in autoimmune diseases such as type 1 diabetes and inflammatory bowel disease (IBD). Reduce it, and the threat of these diseases has been shown to decline.
But how many of us know what inflammation is, why too much is so damaging, or what we can do to protect ourselves from it?
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'Inflammation is a defence system,' says Dr James Kinross, a consultant surgeon and lecturer in colorectal surgery at Imperial College London. 'It is a process through which our body is able to detect harm and regenerate itself once it's sustained an injury.' Cut your finger or catch a cold, for example, and the damaged cells release chemicals that trigger a response to heal you. If all systems are in good order, the inflammation subsides once you are well. Inflammation becomes a risk, Kinross says, when that response isn't switched off again. It's designed to be acute, but not chronic or excessive.
'If it switches on for the wrong reasons or you lose that balance, it becomes problematic,' he says. 'The immune system will literally attack our body's cells and tissues.'
One of its biggest triggers is our modern environment and lifestyle, says the gastroenterologist Shilpa Ravella, the author of A Silent Fire: The Story of Inflammation, Diet and Disease. 'We've altered, among many things, our diet, physical activity, stress levels, sleep, social connections, the quality of the air we breathe, and our exposure to toxins from our household and other products,' she says.
We have never been exposed to so many factors that trigger inflammation in our bodies, and we know this owing to recent strides in molecular medicine. Danny Altmann, a professor of immunology at Imperial College London, says that doctors can now measure a range of biological markers, including cytokines, that increase with excessive inflammation and are signs of 'bad or unhealthy stuff going on'.
Age, for example, increases our susceptibility to inflammation, Altmann says. 'If you do all those biomarker measurements, they grow further and further off-kilter as you grow older, and contribute to poor health.'
In its early stages, persistent low-level inflammation can be silent and 'hidden, simmering quietly in the blood of ostensibly healthy people,' Ravella says. 'One thing to watch out for is belly fat, because it is a proxy for hidden 'visceral' fat that wraps around inner abdominal organs. And this type of fat is highly inflammatory, churning out inflammatory cytokines at all hours.'
She stresses that the risk is more closely related to lifestyle choices than how you look. Improving diet, reducing stress and exercising more frequently can reduce chronic, hidden inflammation 'even without a change in the amount of belly fat one has'. Similarly, you can look fit and slim but harbour silent inflammation if you don't have good lifestyle habits.
To make sense of this link, it helps to understand how the immune system works, says Kinross, who has written a book on the subject, Dark Matter: The New Science of the Microbiome.
Your immune system has two parts. Your innate immune system deals with day-to-day challenges and threats: if your body meets a pathogen, it mounts an immediate response. When your body meets the same pathogen again, the second part of the immune system, the adaptive part, learns how to make antibodies to fight it and creates a more precise strike.
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'This is where the microbiome is so important,' Kinross says. 'You need bugs to educate and set up and teach that system friend from foe. You also need the right balance of microbes because they can speak to that immune system and say, 'Hey guys, you need to ramp up'. But they can also put the brake on.' So healthy gut bugs and a diverse microbiome make for a more efficient immune system.
Kinross believes that the huge rise in conditions that share a common thread of inflammation can be attributed partly to failing to programme our immune systems effectively in early life. The overuse of antibiotics, a diet of nutrient-poor and ultra-processed foods and exposure to pollution all negatively affect the microbiome.
Antonio Vidal-Puig, a professor of molecular nutrition and metabolism at the University of Cambridge, heads a team researching the mechanisms that link obesity with metabolic complications including insulin resistance, diabetes, fatty liver and heart disease. 'Obesity is also associated with neurodegenerative diseases like Alzheimer's, and also with cancer — such as colon, breast, prostate or gynaecological — as well as IBD and many other common diseases,' he says.'Inflammation is a key component in the story everywhere.'
We already know that losing weight cuts obesity-related cancer risk, but a study presented at the European Congress of Obesity in May suggested that losing weight through taking GLP-1 medication (such as Ozempic or Mounjaro) resulted in a 41 per cent greater reduction in risk than if one were to lose the same weight through bariatric surgery.
Obesity can cause chronic inflammation through metabolically abnormal fatty tissues releasing hormones and proteins that reduce anti-inflammatory immune cells across the body, as well as through imbalances in insulin and glucose, says Dr Matthew Harris, a Cancer Research UK clinical research fellow and lead author of PADRAIC, a project at the University of Manchester researching anti-obesity interventions to prevent adult cancers. However, it's likely that there are some direct effects of GLP-1 drugs on the immune system too, he adds. 'There are GLP-1 receptors all over the body — predominantly in the gut, brain and pancreas, but also on immune cells called T-cells that respond to inflammation. While it's likely that the anti-inflammatory effects of GLP-1 drugs are mostly due to a reduction in 'sick fat', it's speculated that there may also be some direct effects on the receptors.'
A Mediterranean-style diet enhances health because it contains fruit, leafy greens and other vegetables, whole grains, legumes, nuts, spices and herbs, all of which have high anti-inflammatory potential, Ravella says. 'These foods contain a host of substances essential for regulating the immune system, like polyphenols, carotenoids and other phytochemicals, as well as unsaturated fats like omega-3s.'
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Our most anti-inflammatory nutrient? Fibre from plant sources. We should be eating 30g of fibre daily, but at least 90 per cent of UK adults are deficient in it. 'Fibre can manipulate all arms of the immune system,' Ravella says.
Ultra-processed foods full of additives, foods that contain an excess of sugar and salt, plus refined carbs and unhealthy animal foods including processed meats can all activate the immune system, stressing cells in the body and triggering inflammation, she says. Alcohol, too, is inflammatory, says Dr Federica Amati, a medical scientist and nutrition lead at Imperial College London.
Colourful fruit and veg and leafy greens 'Fruits and vegetables that are high in antioxidant polyphenols combat oxidative stress and lower inflammatory markers,' says Amati, who is also head nutritionist at the science and nutrition company Zoe and the author of Every Body Should Know This: The Science of Eating for a Lifetime of Health. Colourful fruits are particularly beneficial. Pomegranates, for example, contain specific polyphenols associated with reducing heart disease, she says. Beetroot is another deeply coloured antioxidant-rich plant that helps to reduce inflammation. And yellow-toned plants — papayas, oranges, mangos, apples, carrots and celery — contain the polyphenol apigenin, which has anti-inflammatory effects.
Fruits and vegetables are also high in fibre, which helps to maintain a healthy gut microbiome, and can create short-chain fatty acids, which are good for maintaining the integrity of the gut lining. Cruciferous vegetables such as cauliflower, broccoli and Brussels sprouts, and leafy greens including spinach, Swiss chard and cavolo nero, are particularly beneficial.
Legumes Black beans, chickpeas, lentils and edamame are high in fibre and polyphenols. 'Lentils contain plenty of fibre and plant protein, as well as micronutrients like iron. They are a nutritional powerhouse,' Amati says.
MushroomsMushrooms provide fibre, plant protein and polyphenols that are special to fungi, Amati says. 'Increasing your intake of mushrooms is associated with lower inflammation and if you sunbathe them on your windowsill, they will also contain vitamin D, which is great for immune health.'
Omega-3 fatty acids found in fishSalmon, sardines, anchovies, and mackerel are rich sources of omega-3 fatty acids, but so are flaxseeds, chia seeds and walnuts. Studies have found that they help cells to make more omega-3-derived metabolites which turn off the inflammatory response and work to improve the gut microbiome.
'They're known to have anti-inflammatory properties and are metabolised by the gut microbiome — our gut microbes love omega-3,' Amati says. 'They have properties that are important for reducing inflammation in the liver.'
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Wholegrains such as oats and speltSteel-cut oats, barley, quinoa, buckwheat and spelt contain a fibre called beta-glucan, which has anti-inflammatory properties, reduces cholesterol and helps with heart health.
Nuts and seeds As well as the omega-3 in flaxseeds, chia seeds and walnuts, other seeds and nuts, such as almonds and pumpkin seeds, contain healthy poly and monounsaturated fats. 'They also provide polyphenols of their own that help to lower inflammation,' Amati says.
Extra virgin olive oilThis is in a category of its own. 'It has a clear role in the Mediterranean diet, but as an ingredient itself, its particular polyphenols and fats have very strong anti-inflammatory effects that have been likened to the anti-inflammatory effects of ibuprofen,' Amati says.
Herbs, spices and fermented foodTurmeric, ginger and garlic have potent anti-inflammatory effects thanks to the specific polyphenols found in them, such as curcumin in turmeric and allicin in garlic.
Amati notes that a recent trial by scientists at Stanford University investigated how the gut microbiome and inflammatory modulation changed between a fibre-rich diet and a fermented food-rich diet. 'The high-fibre diet helped to improve immune system function, so it was better able to react appropriately to pathogens. The high fermented-food diet, containing yoghurt, kefir, sauerkraut and kimchi, helped to reduce systemic inflammation, specifically helping to modulate unnecessary inflammatory response.'
Bacon and processed meatsThese are high in salt and saturated fat, both of which cause inflammatory responses in the body and are linked to an increased risk of bowel cancer. 'We think this is due to a combination of the saturated fat and the way they are processed, along with the additives like nitrates and salt,' Amati says. 'They are also not good for the gut microbiome, which makes it easier for the inflammation to go up.'
Sweets and fizzy drinks Foods that are high in sugar will raise your blood sugar level rapidly, also increasing insulin levels, which promotes an inflammatory state in the body. 'Sugar is also absorbed quickly into the liver and the liver doesn't like that,' Amati says.
Factory-made pastries and cakesThese tend to be high in saturated fats and refined carbohydrates, as well as sugar. 'Research has shown that people who have a higher intake of refined carbs have higher inflammatory markers,' Amati says. 'Refined carbs are stripped of fibre, antioxidants and micronutrients during processing, which removes the naturally anti-inflammatory compounds. When sugar reacts with proteins or fats in the body, it forms AGEs [advanced glycation end-products], which accumulate in tissues and trigger immune cells to release inflammatory cytokines.'