The dangers of chronic inflammation – and the worst things for it

Telegraph

08-04-2025

Imagine a glowing couple in their 20s, working and partying hard, getting precious little sleep, says gastroenterologist Shilpa Ravella. Then fast-forward 30 years and the couple may have serious health issues such as Type 2 diabetes or heart disease.
'Late nights, drinking and stress, all these things trigger low-level inflammation which can damage our tissues and then one day it turns into heart disease or cancer,' adds Ravella. 'Yes, younger bodies tend to process things more favourably. But the processed food has got worse, and young onset colon cancer is skyrocketing.'
Being slim isn't a protection, adds Ravella. 'You can be at the gym lifting weights, have big muscles and a flat tummy, but still be highly inflamed. More importantly, you could have a higher risk of disease down the line, without having a clue.'
Hidden, chronic, low-grade, systemic inflammation is a 'hot topic' in health and wellness because it's increasingly recognised as a major driver of heart disease, cancer and Alzheimer's, as well as autoimmune conditions such as inflammatory bowel disease (IBD) and rheumatoid arthritis (where the immune system starts to attack the healthy cells of organs and tissues). And scientists now believe 'inflammaging' is one of several essential factors that drive ageing in humans.
'As we age, just naturally through a combination of genetics and the sum total of our environmental exposures, our immune systems develop a natural propensity for wanting to engage in chronic inflammation,' explains Dr Nathan Curran, a functional Medicine Practitioner at London's The Galen Clinic.
'If we're trying to prevent chronic disease, it needs to go beyond just screening for the disease,' he adds. 'We need to be screening for the actual triggers of the disease before they emerge.'
What is inflammation?
Inflammation isn't bad per se. It's the immune system's response to any traumatic event in the body tissues – for example, a scraped knee or finger cut. In case of 'acute' inflammation, our immune system releases inflammatory cells and cytokines (small proteins that stimulate more inflammatory cells) to neutralise the invading virus or start healing injured tissue. You will experience redness, warmth and swelling, but it will be over in a matter of days. 'Acute inflammation serves a very important role in keeping us alive,' s ays Dr Curran.
In our evolutionary history, in order to protect our bodies from pathogens and poisons, we developed a hyperactive immune system, explains Ravella, author of A Silent Fire: The Story of Inflammation, Diet and Disease.
The problem is inflammation is not always harmless.
'Chronic' inflammation happens when this response is switched on all the time, leaving your body in a constant state of alert. The body continues to send white blood cells on the attack in the absence of any threat. This disrupts normal bodily functions and can result in healthy tissues and organs being attacked. Plus your body never gets a chance to recuperate.
Inflammation and cholesterol
The whole topic of inflammation became a bit more 'personal' last October when I learnt I have 'a propensity for excessive inflammation on a genetic level' when I did a DNA test at Dr Curran's clinic.
The clues were there already: I had high cholesterol and was a point from being pre-diabetic. I sneezed incessantly (and very loudly) after too much fizz or sugar, both of which raise inflammation.
'You have an 'eager/active' variant of the gene,' Dr Curran tells me. 'This means a relatively mild trigger has the potential to trigger a disproportionately large/sustained release of TNF-alpha (a pro-inflammatory protein), unless we moderate the impact of this genetic variation through an anti-inflammatory lifestyle, omega-3 s, Vitamin D and so on.'
I immediately Google TNF-alpha and find that, worryingly, this cytokine is implicated in acute and chronic inflammatory conditions including, sepsis, rheumatoid arthritis and dementia.
'Just because you have the genetic propensity doesn't mean it will be translated into excessive inflammation,' he adds, 'but you need to be mindful of your lifestyle and dietary exposures.'
But there's my family's history of heart disease to consider, too. 'When cholesterol accumulates in the arteries, it creates inflammation because it gets modified and oxidised,' explains British Heart Foundation Professor of Cardiovascular Medicine at the University of Cambridge, Ziad Mallat. 'And then the body recognises it as a stranger. This inflammation initially serves to clear the oxidised cholesterol from the arteries. But when the body is exposed continuously to this aggression, the clearance capacities become overwhelmed and the inflammation becomes chronic. This causes more build-up of fatty material in the arteries and later may create clots in the arteries, and cause heart attack and stroke. The same thing happens when you have high glucose in diabetes, or if you smoke; it causes injury to the arteries and that creates chronic inflammation.'
The shock motivated me to change my diet (I gave up free sugar, brought my cholesterol down naturally for this paper). Then in March I asked my GP for a CRP (C-reactive protein) blood test (CRP is produced by the liver and if there's a higher concentration of CRP than usual, it's a sign of inflammation) and, phew, it's normal at the moment. The sneezing has stopped.
'You were really lucky, because your sneezing was so obvious and not everybody has that,' says Thaddeus Stappenbeck, MD, PhD chair of Inflammation and Immunity at Cleveland Clinic. 'Most people have more vague symptoms, like they don't have the energy they used to, or they're not sleeping well.'
At Cleveland Clinic, Dr Thaddeus's research programme focuses on determining the root causes of inflammatory diseases with the goal of developing new therapies. 'With certain types of inflammatory conditions, they can programme parts of your immune system so they simply malfunction which further fuels inflammation later. A really good example is sepsis. Patients who have had bloodstream infections and spent time in intensive care, if they survive and are able to leave the hospital, what's well recognised is that parts of their immune system are no longer functional. So they're at risk for repeat infections with worse overall inflammation.'
The role of diet and the gut microbiome in inflammation
The function of the immune system is to protect us from invaders—and to be able to tell apart the cells of our own body from other cells that don't belong to us. And scientists have estimated that about 70 per cent of the immune system lives in the gut microbiome. Chronic inflammation in the gut may be due to inflammatory bowel disease, such as Crohn's disease or ulcerative colitis. But a modern Western diet high in ultra-processed foods can literally cause our whole body to be on fire, too. The poorer the quality of a meal, the higher the inflammatory response. Our microbiome (and the trillions of bugs in our intestines crucial to human health) is worryingly damaged, in contrast to our ancestors who had better gut health.
This sort of inflammation contributes to most of our '21st-century' diseases, says Dr Stappenbeck. 'The link between what's going on in your gut microbiome, and diseases such as Alzheimer's, Parkinson's or sleep disorders or depression is really amazing. We're learning, for example, that Parkinson's disease probably starts in many of these patients in the colon and becomes more evident once brain lesions have developed. A lot of patients with Parkinson's have very severe constipation because the neurons in their colon are damaged and don't function properly. They could have been experiencing that for years without realising. So could we diagnose Parkinson's earlier before the cells of the brain are damaged?'