Right now, while you’re reading this, your immune system is quietly hard at work; scanning, defending, remembering, repairing. It’s been doing this every single day of your life. But just like your skin, your bones and your muscles, it doesn’t stay the same as the years go by. It ages too. Scientists call this process immunosenescence: the gradual, entirely natural decline and remodelling of the immune system that happens as we get older.
Here’s the surprising part: it’s easy to assume immune health only becomes something to think about later in life, but the truth is these changes start much earlier than most of us realise, often in our mid-twenties - long before we notice we’re catching more colds or taking a little longer to shake them off. The good news is that once you understand what’s happening beneath the surface, you’re in a much better position to support your immune system at every age, not just once it starts to show.
So let’s take a closer look: what immunosenescence actually is, when it begins, the impact it can have on your everyday health, and most importantly, the nutrients and lifestyle habits that can help you support your immune system, whatever age you’re at.
What is immunosenescence?
Think of immunosenescence as your immune system’s own ageing process the same kind of gradual change your skin or joints go through, just happening somewhere you can’t see. It’s the term researchers use to describe the natural deterioration and restructuring of the immune system that occurs with age, and it touches both sides of your immune defences: your innate immune system (the fast-acting, general first responders) and your adaptive immune system (the smarter, more specific defences built up from a lifetime of exposure to bugs and vaccines).
It isn’t one dramatic event, more a slow, quiet remodelling. Immune organs shrink a little, the balance of immune cells shifts, communication between cells becomes less efficient, and, in a strange twist, the immune system ends up both weaker in some ways and oddly more prone to unhelpful inflammation in others. Researchers call this a paradox: an immune system that under-reacts to genuine new threats while over-reacting with chronic, low-level inflammation.
When does immune ageing actually begin?
If you’re picturing immunosenescence as something that only creeps in during your seventies or eighties, it’s worth rethinking that. One of your immune system’s most important organs, the thymus (where T cells mature and learn to recognise threats), actually begins shrinking from birth, losing around 3% of its tissue every year until your mid-30s to mid-40s, before settling into a slower, steady decline for the rest of your life.
In other words, the groundwork for immunosenescence is often being laid in your twenties and thirties, even if you feel completely fine. The consequences, catching more bugs, taking longer to recover, a slightly less robust response to vaccines, tend to become noticeable later, usually from your fifties onwards. And if you’re navigating the hormonal shifts of perimenopause or menopause, which can influence immune and inflammatory activity too, immune health can start to feel like a much more pressing concern from your forties.
The real takeaway here is a reassuring one: immune ageing isn’t a switch that flips at 60. It’s a slow, gentle drift that starts decades earlier, which is exactly why it’s worth supporting your immune health early, rather than only thinking about it once cold and flu season hits.
What happens inside the body as the immune system ages
Thymic Involution and Fewer New Immune Cells
As your thymus gradually shrinks (known as thymic involution), it produces fewer new “naive” T cells, the cells whose job is to recognise threats your body hasn’t met before. With fewer new recruits joining the ranks, your immune system leans more heavily on its existing “memory” cells, which can narrow its ability to respond effectively to new viruses and infections.
A narrower range of immune responses
Alongside these T cell changes, the diversity of your antibody-producing B cells contracts a little with age too. Put together, these shifts mean your immune system’s overall repertoire, its ability to recognise and respond to a wide variety of pathogens, becomes narrower over time.
Inflammaging: chronic, low-grade inflammation
One of the most fascinating discoveries in immune ageing research has its own name: inflammaging. It describes a persistent, low-grade inflammatory state that builds with age, even when there’s no active infection to fight. It’s thought to be a major driver of many age-related health concerns, and it sits alongside immunosenescence as two sides of the same coin; one reflecting a weakened response to real threats, the other an immune system that struggles to switch off.
A slower innate response
Your innate immune system, your body’s rapid-response unit, also becomes a little less efficient with age, responding more slowly and less precisely to pathogens. In practice, that can mean infections take hold more easily and take longer to clear.
Shifts in gut health
A significant proportion of your immune tissue actually lives in your gut, so it makes sense that your gut microbiome shifts with age too, with a natural decline in the diversity of beneficial bacteria. Because gut and immune health are so closely linked, this shift can compound the other changes happening across your immune system.
The real-world impact of immunosenescence
More frequent, longer-lasting infections
With a narrower range of immune responses and a slower innate reaction, it’s more common to pick up seasonal bugs, and to find they linger a little longer or hit a little harder than they used to.
Slower recovery and healing
Immune cells play a central role in tissue repair, so as their number and efficiency decline, wounds, infections and general recovery from illness or exertion can all take a bit longer than they once did.
Reduced vaccine response
With fewer naive T and B cells available to mount a strong response to new antigens, vaccines can become somewhat less effective at generating robust, long-lasting protection as we age, one of the reasons booster and higher-dose vaccines are often recommended for older age groups.
Greater susceptibility to age-related conditions
Chronic inflammaging is thought to contribute to many of the health concerns associated with getting older, which is exactly why keeping inflammation in check is such a central theme in longevity research.
A knock-on effect for skin
Here’s something you might not expect: immune ageing and skin ageing are more connected than they first appear. Inflammaging can speed up the breakdown of collagen and elastin in the skin, contributing to the fine lines, sagging and dullness we associate with visible ageing. It’s a lovely reminder that supporting your immune system isn’t just about fighting off colds, it’s part of the very same inside-out picture as supporting your skin’s structure, which is exactly why so many of us reach for both immune support and a daily collagen supplement like Collagen Shots as we get older.
Can you support your immune system as it ages?
Here’s the empowering part: while immunosenescence is completely natural and universal, research shows that lifestyle plays a real role in how gracefully your immune system ages. A few of the most evidence-backed habits worth building into your routine:
- Prioritise consistent, good-quality sleep, this is when your immune system does much of its regulating and repairing
- Keep moving; regular, moderate exercise is linked to better immune surveillance and lower chronic inflammation
- Look after your stress levels, as chronically high cortisol can suppress healthy immune function
- Eat a varied, plant-rich diet to supply the vitamins, minerals and antioxidants your immune system relies on
- Support your gut with fibre and fermented foods, given how closely gut and immune health are linked
- Go easy on alcohol and steer clear of smoking, both of which place extra strain on immune function
Nutrients that help support immune function Alongside these everyday habits, certain nutrients have a well-established role in supporting the immune system, which is exactly why we formulated Immune Complex around a targeted blend of vitamins, minerals and plant extracts:
- Vitamin C - A water-soluble vitamin well known for its role in supporting a healthy immune system. Vitamin C, selenium and zinc all contribute to the normal function of the immune system and to the protection of cells from oxidative stress.
- Vitamin D - Plays a key role in supporting the immune system, with research showing it helps activate T cells. Vitamin D also contributes to the normal function of the immune system and the maintenance of normal muscle function.
- Zinc - Essential for the immune system, influencing how cells respond to infection, helping keep inflammation in check, and increasing the activation of infection-fighting cells. Zinc also plays a role in the process of cell division.
- Selenium - An essential mineral that plays an important role in supporting healthy immune function.
- Beta Glucans (Beta 1,3 and Beta 1,6) - Healthy fibres derived from the cell walls of baker’s yeast. They’re absorbed into tissue in the small intestine, where they bind to neutrophils, the most abundant immune cells in the body.
- Açaí Berry - Rich in vitamins, polyphenols, polysaccharides and amino acid proteins, providing key building blocks for the immune system.
- Elderberry Extract - Packed with antioxidants and vitamins that help support the body’s natural immune response.
- Turmeric – Traditionally recognised for its anti-inflammatory properties. Its active compound, curcumin, has been studied for its potential to modulate the activity of T cells, B cells, macrophages, neutrophils, natural killer cells and dendritic cells.
- Astragalus Root (Astragalus membranaceus) – A traditional Chinese herb long used to help stimulate and regulate immune activity.
- Cordyceps – A rare wild mushroom found across the Himalayas, Tibet and China, valued for its prebiotic properties and traditionally used to support the respiratory system.
- Lactobacillus – A beneficial bacteria strain that supports healthy digestion and absorption and promotes a balanced gut, which, as we’ve seen, is closely tied to immune resilience. Note: traditional herbal uses reflect historical and cultural use rather than clinically established outcomes; food supplements are not intended to diagnose, treat, cure or prevent any disease.
Immune Complex: targeted, everyday immune support Immune Complex brings all of the above together in one simple daily capsule, designed to become part of your everyday routine, not just something you reach for once you’re already feeling run down.
How to take it: One capsule a day, increasing up to three if you’re fighting a cold or infection.
Who shouldn’t take it: Don’t take this product if you’re pregnant or breastfeeding. If you’re taking any medication or have health concerns, please check with your doctor before use. Don’t exceed the daily dosage, and keep out of reach of children.
Immunity is part of the bigger longevity picture
At Rejuvenated, we see ageing as a whole-body story, which is why immune support sits alongside our collagen and longevity ranges rather than apart from them. Just as your immune system remodels itself with age, so does your skin’s connective tissue, which is why our best-selling Collagen Shots exist to support skin firmness and elasticity from within, while our longevity-focused formulas help support your body’s natural repair processes more broadly. Immune health, skin health and cellular health are all threads of the same story: supporting your body from the inside, as it changes with time.
FAQs about immunosenescence
What is immunosenescence in simple terms?
Immunosenescence is the natural, gradual weakening and restructuring of your immune system that happens as you age. It affects how well your body recognises and responds to infections, and how quickly you recover afterwards.
At what age does the immune system start to decline?
Your thymus, a key immune organ, begins shrinking from birth and continues at a faster rate until your mid-30s to mid-40s. This means the underlying changes of immunosenescence begin far earlier than most people expect, even though the effects usually become more noticeable from your fifties onwards.
What’s the difference between
immunosenescence and inflammaging? Immunosenescence refers to your immune system becoming less effective at responding to new threats. Inflammaging refers to the chronic, low-grade inflammation that tends to develop alongside it. Researchers consider them two connected sides of the same age-related process.
Can immunosenescence be reversed?
Immunosenescence can’t be stopped or reversed entirely, as it’s a natural part of ageing, but research suggests that lifestyle factors such as sleep, exercise, stress management, gut health and targeted nutrition can help support immune resilience as your body ages.
What nutrients support an ageing immune system?
Vitamin C, vitamin D, zinc and selenium all have an established role in supporting normal immune function, alongside ingredients such as beta glucans, elderberry, astragalus and cordyceps, which have traditional or emerging research support.
Is Immune Complex suitable for everyone?
Immune Complex is designed for adults looking to support everyday immune function. It shouldn’t be taken if you’re pregnant or breastfeeding, and anyone on medication or with existing health concerns should check with a doctor before use.
How does immune ageing affect the skin?
Immune ageing and skin ageing are linked through inflammaging, which can speed up the breakdown of collagen and elastin. Supporting both your immune system and your skin’s collagen levels, with a daily supplement like Collagen Shots, is a lovely, complementary, inside-out approach to visible ageing.
To summarise
Immunosenescence is a natural, universal part of getting older, and one that begins far earlier than most of us realise. While it can’t be stopped, understanding it puts you in a much stronger position to support your immune system proactively, through sleep, movement, stress management, gut health and targeted nutrition, rather than only reaching for support once you’re already feeling the effects. Ready to give your immune system a little extra support?
Discover Immune Complex and explore our full Immunity range. This article is for general information purposes and does not constitute medical advice. If you have a health condition or are taking medication, please speak to your doctor before starting any new supplement.
