Normally, inflammation is important to our bodies mounting an immune defence when we get an infection or injury and shutting off when the threat passes.

With inflammageing, however, inflammation persists even when there is no infection to fight. (“The purpose of this inflammation is actually still unclear,” Dixit says.)

A major source of the smouldering, inflammatory signals seems to be stressed-out, damaged cells that release proteins indicating “something is not going well”, says Alan Cohen, an associate professor of environmental health sciences at Columbia University’s Mailman School of Public Health.

“As we age, our internal stressors increase. This is more or less inevitable. Something is not going well. In any species that ages, something is not functioning as well with age,” he says.

Inflammageing and health

Inflammageing has been strongly associated with several age-related health conditions, including atherosclerosis, cardiovascular diseases, diabetes, frailty, dementia and death.

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It may be the “predecessor” for many of these diseases, Vaccari says.

For example, Alzheimer’s disease – the most common type of dementia – is believed to start up to 20 years before cognitive changes become apparent, and there is growing evidence that an underlying inflammatory response is already present during this time, Vaccari says.

Known risk factors for inflammageing include increased visceral fat, which wraps around internal organs, and uncontrolled blood sugar levels, Vaccari says.

Inflammageing is “really strongly associated with a lot of bad outcomes, so we know, in general, that you’re probably better off if you don’t end up with a very high level of inflammation as you get older,” Cohen says.

Researchers are working on unravelling the specific mechanisms of inflammageing for earlier diagnosis and more targeted treatment.

Studies have found that specific cytokines – proteins secreted by cells that coordinate immune and inflammatory responses – such as IL-6 and IL-1β, are consistently implicated in inflammageing.

“Moving forward, what is really going to be exciting is for us to understand which one of these pathways are adaptive and which ones are maladaptive,” Dixit says.

Inflammageing (as we know it) is not universal

In a recent study, Cohen and his colleagues found that inflammageing – at least as it is commonly measured with cytokines – is not universal, and seems to correspond with an industrialised lifestyle.

Researchers compared immune marker data from people living in two industrialised countries, Italy and Singapore, with data from Indigenous people living in two non-industrialised regions, the Tsimane of the Bolivian Amazon and the Orang Asli of parts of Malaysia.

Among the Italians and Singaporeans, the inflammageing factors generally matched and were associated with age and chronic age-related diseases such as chronic kidney disease.

But when the researchers looked at the Tsimane and Orang Asli, neither population followed the inflammageing pattern as people from the industrialised countries as they got older. They also did not have the profile of chronic diseases that normally crops up with age in industrialised countries.

“It really became clear that they’re not doing anything like what the industrialised populations are doing,” said Cohen, who was the senior author of the study.

This wasn’t to say that the people from non-industrialised regions did not have inflammation. On the contrary, for the Tsimane in Bolivia, inflammation stayed high throughout their lives, probably because of common infections. About 66 per cent of Tsimane have at least one intestinal parasitic infection, while 70 per cent of Orang Asli have a prevalent infection, including respiratory and fungal, at any given time.

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And among Italians and Singaporeans, the inflammageing patterns weren’t exactly the same. The cytokine IL-6, which is often considered a key indicator of inflammageing, did not correlate with age in the Singaporean population.

There may be underlying commonalities to immune ageing, but how they manifest may depend on the context, says Cohen, who wrote a recent review.

“We should not think of inflammation as a problem in and of itself,” says Cohen, who likens it to a fire alarm.

The fire alarm may not be pleasant, but often it indicates that something isn’t going well in the building, he says. But “none of this means you don’t want the fire alarm system installed or that you want to deactivate it,” Cohen says.

How to manage inflammageing

A healthier lifestyle in your younger years will benefit you in your older years.

“Life is interesting in that sometimes it starts sending you a bill for the things you did 20 years earlier,” Vaccari says.

Older people who already have high inflammation could adopt more targeted approaches to address the root causes of inflammation, Cohen says.

Controlling blood pressure, reducing visceral fat and managing blood sugar levels “would go the longest way possible for a healthy lifestyle”, Vaccari says.

There is not enough evidence to recommend a particular diet, Dixit says, but managing caloric intake may be helpful because caloric restriction is linked to longevity and health. In a recent preprint study, which has not been peer-reviewed yet, Dixit and his colleagues report that reducing caloric intake by 14 per cent could reduce a key immune marker important to inflammation.

Stay nourished, but “it doesn’t hurt every now and then to feel hungry”, Vaccari says.

Don’t take sleep for granted because it “helps the brain get rid of toxins”, he adds.