The Balanced Body: How Your Immune System Keeps You Alive (and What Happens When You Push Too Hard)
By Dr Jenna Macciochi - Immunologist specialising in the intersection of nutrition, movement, mind-body practices and lifestyle with the immune system in health and disease.
Every second of every day, your body is negotiating with the world. A constant conversation between what’s inside and what’s outside of you. This conversation is your immune system: an exquisite network of cells, molecules, tissues, and organs working tirelessly to keep you alive.
Far from being just a defence mechanism, your immune system is an orchestra of balance. It’s the reason a small scratch heals, a cold eventually clears, and you can coexist with trillions of microbes without chaos. But in the modern world, where stress, sleep loss, nutrient gaps, and over-sanitising have become the norm, this system is being asked to do something it was never designed for: thrive in constant overdrive.
How Your Immune System Really Works
The immune system isn’t one thing, but rather a beautifully integrated system that connects to every aspect of your biology — your brain, hormones, metabolism, even your mood. It’s less a fortress and more a smart surveillance network, continuously sensing, communicating, and adapting.
At its simplest, there are two arms: innate immunity, your first line of rapid, non-specific defence; and adaptive immunity, the slower but more specialised response that builds memory and long-term protection.
The innate system includes barriers like your skin and gut lining, as well as cells that patrol for danger, clearing debris and sending out alarm signals. The adaptive arm, made up of B and T cells, learns, remembers, and fine-tunes its response each time you encounter a microbe.
But what often goes unrecognised is how intimately your immune system and nervous system are entwined. Together, they form part of the body’s ancient threat-detection network, constantly scanning for signs of danger, both physical (like viruses or wounds) and psychological (like social rejection or chronic stress).
This is the science of psychoneuroimmunology: the study of how your mind, brain, and immune system communicate. Your brain doesn’t distinguish between a virus and a work deadline; both activate similar pathways of vigilance. When your nervous system senses threat, it reallocates energy away from long-term processes like repair, digestion, and reproduction, and channels it towards short-term survival.
But here’s the beauty: the immune system isn’t just fighting. It’s regulating, repairing, and restoring balance every moment. You could say it’s not built for war, but for wisdom.
From an evolutionary perspective, this makes perfect sense. For most of human history, threats were acute, a predator, an injury, a famine. Short bursts of immune activation and stress hormones like cortisol were lifesaving. But in modern life, our threats are chronic and psychological, financial pressure, social comparison, constant notifications, keeping this ancient system switched on for too long.
Over time, this “energy triage” can leave us depleted, inflamed, and vulnerable. The immune system becomes stuck in low-grade activation, mistaking everyday stress for ongoing danger.
You could think of immunity as the body’s ultimate energy economist — constantly deciding where to spend, where to save, and when to repair. And like any economy, imbalance comes at a cost.
What Happens When You Catch a Virus
When you catch a cold or flu, your immune response follows a finely choreographed dance. First, the innate system detects viral particles and releases chemical messengers called cytokines. These recruit immune cells to the site of infection, raise your body temperature, and trigger symptoms like fatigue and fever, not signs of weakness, but evidence that your body is fighting smart.
Next, your adaptive immunity kicks in. Specialised T cells identify and destroy infected cells, while B cells produce antibodies, tiny molecular “wanted posters” that neutralise the invader. Once the infection clears, memory cells remain, allowing your body to respond faster if the same pathogen returns.
Recovery isn’t just about killing the virus; it’s about resolution. Your body has to actively switch off inflammation, repair tissue, and restore equilibrium. This “cool down” phase is where much of our modern imbalance begins to show.
Immunity and Energy
Feeling run-down or constantly fatigued isn’t just about sleep, it can be a sign your immune system is struggling to find balance. The immune and energy systems share many of the same molecular pathways. When immune cells are active, they demand fuel — glucose, amino acids, fatty acids, diverting energy away from things like focus or physical performance.
This is why when you’re ill, you feel tired: your body is re-prioritising. But when chronic stress or inflammation keeps your immune system on low-grade alert, it can drain energy reserves continuously. You’re not lazy, you’re depleted by biology.
Low-Grade Inflammation: The Silent Disruptor
Inflammation is vital, it’s how we heal. But when it’s switched on and never turned off, it becomes the quiet saboteur of wellbeing. Chronic, low-grade inflammation is linked to everything from fatigue and poor mood to metabolic and cardiovascular disease.
Its triggers are diverse: psychological stress, poor sleep, ultra-processed diets, sedentary lifestyles, environmental toxins, even loneliness. Each sends subtle “danger” signals that keep the immune system slightly on edge.
The symptoms can be equally subtle, brain fog, energy dips, aches, digestive changes, skin flare-ups, easily dismissed as “just life”. But they’re signs your immune system is overworking, not underperforming.
The Overprotected Body
We’ve become a society obsessed with cleanliness — antibacterial everything, constant hand-sanitising, germ-free environments. While hygiene is essential in preventing infection, excessive sterilisation can starve the immune system of the training it needs.
Our immune cells learn through exposure, especially in early life. The microbes we encounter on food, soil, and in natural environments act like tutors, teaching our defences to tell friend from foe. Too little microbial diversity can leave the system under-educated — more likely to overreact to harmless triggers, increasing allergies, asthma, and autoimmune tendencies.
Rewilding our health isn’t about being careless, but about balance: spending time outdoors, eating a variety of whole foods, embracing some healthy messiness. Your immune system thrives on information, not isolation.
The Immune System’s Memory
Every encounter your immune system has leaves an imprint. Some are fleeting, like seasonal colds, others lifelong, such as measles or chickenpox. But this memory isn’t just about microbes, it also records lifestyle.
Chronic stress, poor nutrition, or repeated infections can “reprogram” immune cells, altering how they respond to future challenges. Conversely, good sleep, regular movement, social connection, and balanced nutrition can create a more adaptable, tolerant immune system.
Think of immune memory not just as remembering enemies, but as remembering patterns, what balance feels like, and what imbalance feels like too.
Nutrients That Truly Nourish Immunity — Beyond Vitamin C
Despite popular belief, there’s no single supplement that can “boost” your immune system. What it needs is nourishment, not stimulation. Nutrients work synergistically, each playing a unique role in building the structural and functional resilience of immune cells. We could say that a deficiency in any key nutrient would have a negative impact on the immune system. But there are a few key players.
Protein provides amino acids essential for antibody production and tissue repair.
Vitamin D modulates immune tolerance and inflammatory balance.
Zinc and selenium support antioxidant defences and the integrity of mucosal barriers. These can be useful as supplements upon onset of symptoms but otherwise should be prioritised in a healthy balanced diet.
Omega-3 fatty acids help resolve inflammation, turning off the immune response once the threat has passed. In the UK, the average intake of oily fish suggests that we are not getting enough.
Phytonuteitns like polyphenols in colourful fruits, vegetables, teas, and herbs act as gentle molecular signals, supporting microbiome diversity and cellular resilience. These are longevity nutrients, important for long term immune health.
Food synergy matters more than high-dose heroics from supplements. A plate that’s diverse in colour, texture, and plant variety is one of the simplest ways to feed your immunity well. Supplements can then be a targetted tool to support, and shouldn’t be seen as a quick fix or replacement for a food first approach.
Supporting Balance
Immune health isn’t a project to optimise, but a relationship to nurture. The goal is harmony, not hypervigilance.
Here are small, practical ways to stay in dialogue with your body’s defences:
Respect rest. Sleep is when your immune system learns, consolidating memory, clearing inflammation, and resetting its rhythm.
Manage modern stress. Breathwork, time in nature, and meaningful connection are powerful immune regulators. Chronic stress is the most proven factor that weakens immunity over time.
Move often, gently. Moderate exercise enhances immune surveillance, while overtraining suppresses it.
Feed your microbes. A fibre-rich, minimally processed diet fuels the gut microbiome, home to 70 per cent of your immune cells.
Allow imperfection. Occasional exposure to dirt, germs, and discomfort is part of building resilience.
In the End, It’s About Dialogue, Not Defence
Your immune system isn’t your enemy to tame or your armour to polish, it’s your lifelong companion, constantly adapting to help you meet the world.
When you learn to live in dialogue with it, listening to fatigue as a signal, responding to stress with care, embracing nourishment over punishment, you rediscover what immunity truly means: the art of staying in balance.
Love from Fallon, with intention xox
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