Does your immune system age at a different rate than your heart?
Yes, your immune system and heart age at measurably different rates, and an ageing immune system is more strongly linked to a longer life than the heart is. These are associations, not causal evidence, but that is still a reason to take both seriously.
Organs do not age at the same pace in the same person. Studies using blood proteins from tens of thousands of people show that the immune system, heart, brain, and kidneys each have their own ageing rate that differs measurably from one another.
The immune system and the heart both illustrate what is at stake when they age faster than the rest of the body. In the Whitehall II study (more than 6,200 participants followed for twenty years), an ageing immune system was associated with a hazard ratio of 1.36 for developing multiple diseases at the same time across different organs. An ageing heart gave a hazard ratio of 1.52 for that same multi-disease burden, and for chronic heart failure the figure was 1.65. Both organs carry risk, but in different ways and with different outcomes.
The immune system also has something distinctive: together with the brain, it is the only organ that shows a clear link with a longer life. In a study of 44,498 participants from the UK Biobank, people with both a 'youthful' immune system and youthful brain had a 56% lower risk of death than average. Separately, a youthful immune system and youthful brain each gave a comparable halving of that risk (hazard ratio around 0.58 and 0.60 respectively). The heart did not stand out in that analysis.
Long-term low-grade inflammation may widen the ageing gap between organs. Using blood measurements from more than a thousand people, researchers developed an inflammation score with the help of artificial intelligence, which predicted both heart ageing and frailty. One substance produced by immune cells turned out to be the strongest driver of artery hardening. In experiments with cells and mice, damage to the artery wall was partly reversed by blocking that substance, but whether this also works in people has not yet been studied.
All of these associations are based on measured connections, not proven cause and effect. Men age faster than women in most organs, and lifestyle, diet, and medication are linked to the rate of ageing in each organ, though the effect varies by factor and by organ.
All claims are based on large studies that followed people over time and one smaller Spanish study. Whether these connections are actually caused by the factors identified has not been proven. The findings on heart-immune interaction are partly supported by studies in cells and animals.
Does your immune system weaken as you get older?
Your immune system demonstrably weakens with age, but eating healthily and exercising can reduce the smouldering inflammation that accompanies it. It is still too early to rely on drugs targeting senescent cells.
What does ageing of your immune system mean for your health?
Your immune system ages in measurable ways: it responds less effectively to new threats and maintains a smouldering inflammation that is associated with cardiovascular disease, dementia and cancer. An active lifestyle is the best-supported way to slow that process.
How does your immune system age and can a blood test measure that?
Your immune system ages in recognisable ways: exhausted immune cells and smouldering inflammation are clearly visible features. The markers on which a blood test would be based are already well described, though no such standardised test yet exists.
Can you slow down the ageing of your immune system?
There is concrete evidence that lifestyle changes, in particular a Mediterranean diet combined with more physical activity, can meaningfully reduce the number of aged immune cells; probiotics and vitamin D also show measurable effects, though it remains unclear whether this actually leads to falling ill less often.
Does exercise help your immune system as you get older?
Exercise helps older adults: it lowers mild inflammation in the blood and noticeably reduces the risk of physical frailty. How it works on the deeper ageing of the immune system remains an open question.
Does your immune system really weaken as you get older?
Your immune system demonstrably weakens with age, but vaccinations remain worthwhile and a good diet can limit further decline.