ABOUT FLEUR BORRELLI
Where your nervous system, your history, and your health, finally connect.
I work at the intersection of neuroscience, immunology, endocrinology, and nutritional medicine, tracing the original mechanism behind your symptoms rather than managing them in isolation.
BSc Nutritional Medicine · MSc Clinical Psychoneuroimmunology · 20+ years clinical experience · London
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The clinical background
I hold a BSc in Nutritional Medicine and an MSc in Clinical Psychoneuroimmunology from the Pruimboom Institute. I am one of a small number of clinical psychoneuroimmunologists in the UK, a discipline that sits at the intersection of neuroscience, immunology, endocrinology, and nutritional medicine.
I have over 20 years of clinical experience working with people dealing with complex, chronic, and unresolved health conditions. I have co-authored The In-Sync Diet with actress Glynis Barber; an evolutionary approach to fat burn, hormonal balance, and long-term wellbeing. I also help deliver Intermittent Living immersive experiences through the Pruimboom Institute in Spain.
Most people who come to me have already been through the system. They have had the tests, tried the protocols, and been given supplements that helped only partially or not at all. What they have not had is someone who looks at the whole picture.
The personal part
My path into this work was not accidental.
A discovery about my father's wartime trauma, and the way it had silently shaped our family's health, set me on a course that has defined my clinical thinking ever since.
What happens to us, and how we adapt to it, shows up in the body long after the event has passed. The nervous system holds our story. Our immune system reflects the adaptation and the symptoms that appear years or decades later are not random. They are the biological record of everything we have lived through.
My work is to join those dots and find the original mechanism that changed your biology, to help you understand your body in a way that finally makes sense.
WHAT MAKES MY WORK DIFFERENT
The human body is not a network of separate systems; everything is connected all of the time.
Clinical psychoneuroimmunology is not an add-on to standard nutritional therapy. It is a fundamentally different framework and it changes the way you look at health entirely.
Your nervous system talks to your immune system. Your immune system talks to your metabolism. Your metabolism talks to your brain. Your brain talks to your hormones. And all of them are listening to your history, your environment, your social context, and your internal experience simultaneously.
This is anatomy and physiology and yet it is not the framework most practitioners are trained to use.
Rather than managing symptoms in isolation, I work to identify the original mechanism, which is the point at which your physiology changed, and address that directly. The goal is not symptom suppression. It is genuine physiological resolution.
And you will not be asked to buy lots of expensive supplements.
THE FRAMEWORK
The nervous system and the stress connection.
One of the most consistent threads I see in people who come to me is a nervous system that has been under pressure for a long time, often since long before the symptoms appeared.
Stress is not just a feeling. It is a whole-body physiological event. When the nervous system perceives threat, it activates the stress axis, triggering a coordinated response across our whole body. In the short term this is adaptive and intelligent, the body doing exactly what it is designed to do.
The problem begins when the original threat is never resolved. When the nervous system never receives the signal that it is safe to stand down, the stress axis stays activated and over time, chronic activation of that axis begins to dysregulate the very systems it was designed to protect.
What chronic stress does
Cortisol resistance develops. Insulin resistance follows. Leptin resistance disrupts appetite and energy regulation. The immune system shifts from acute and responsive to low-grade and chronic. Gut barrier integrity is compromised. Hormonal balance is lost.
Why symptoms are messages
These are not separate conditions. They are expressions of the same unresolved adaptive programme — a nervous system still running a survival response to a threat that may have begun decades ago. In the cPNI framework, symptoms are biological commands. The question is not how to suppress them. It is what they are signalling, and why the body has not been able to resolve it.
HOW I WORK
The core disciplines.
Every programme is built around your specific clinical picture , there is no standard protocol. What I use depends entirely on the original mechanism driving your condition, the systems implicated, and the history behind it.
01
Functional Nutrition & Food as Medicine
Food is not just fuel. Every meal sends a signal to your immune system, your nervous system, your gut microbiome, and your hormonal axis. Functional nutrition uses food precisely and therapeutically as a clinical intervention targeted at the specific biological mechanisms driving your condition.
02
Intermittent Living Strategies
Humans were not designed for monotonous living. We evolved in an environment of constant change with periods of activity and rest, feast and fast, challenge and recovery. Intermittent living strategies restore that variation deliberately and precisely, giving the body the inputs it was made for.
Read the science behind Intermittent Living →
03
Exercise as Medicine
Movement is one of the most powerful anti-inflammatory and neuroregulatory tools available. Exercise works at the level of immune modulation, mitochondrial function, neuroplasticity, and metabolic flexibility , not just fitness.
04
Immune System Modulation
In chronic conditions the immune system is rarely simply overactive or underactive; it is dysregulated and has learned a pattern of response that no longer benefits us. Immune modulation uses targeted nutritional, lifestyle, and neurobiological interventions to recalibrate that response.
05
Gut Barrier Restoration
The gut barrier is one of the most immunologically active surfaces in the body. When its integrity is compromised, through stress, diet, infection, or nervous system dysregulation, the immune and neurological consequences extend far beyond the gut itself.
06
Solution Focused Strategies & Deep Learning
Solution focused strategies work with the neurobiology of change. Understanding your own biology is physiologically transformative; new pathways form and behaviour shifts. These strategies actively work with the brain's reward and motivation systems to support physiological as well as behavioural change.
WHO I WORK WITH
Conditions and presentations.
I work with people dealing with a wide range of chronic, complex, and unresolved conditions as well as those who feel mainly well but want a clearer picture of their metabolic and immunological health.
AUTOIMMUNE
Hashimoto's thyroiditis
Rheumatoid arthritis
Lupus
Psoriasis
Multiple sclerosis
Inflammatory bowel disease
Coeliac disease
METABOLIC & HORMONAL
Metabolic syndrome
Insulin resistance
Type 2 diabetes
Weight management
Thyroid dysfunction
Adrenal dysregulation
PCOS
Perimenopause & menopause
Premenstrual syndrome
Erectile dysfunction
GUT & DIGESTIVE
Irritable bowel syndrome
Small intestinal bacterial overgrowth
Leaky gut
Crohn's disease
Ulcerative colitis
Bloating
Constipation
Reflux
NEUROLOGICAL & MOOD
Anxiety
Depression
Brain fog
Burnout
Chronic stress
Post-traumatic stress
Insomnia
Poor sleep quality
Migraines and headaches
Alzheimer's disease
Parkinson's disease
Mild cognitive impairment
Age-related cognitive decline
SKIN
Eczema
Psoriasis
Acne
Rosacea
Urticaria
ENERGY & IMMUNE
Chronic fatigue syndrome
Long Covid
Fibromyalgia
Frequent infections
Poor immune resilience
Chronic pain
Inflammation
ADVANCED TESTING
Where clinically indicated.
Testing is never used as a starting point, rather it is used to confirm and deepen what the clinical picture is already telling us. Where indicated, I may use advanced functional medicine testing to build a more precise picture of what is happening in your body.
FUNCTIONALDX: Advanced functional medicine blood chemistry analysis
MICROBA: Advanced gut health analysis
DUTCH: Advanced hormone testing
READY TO BEGIN
Find the original mechanism behind your symptoms.
A 60–90 minute Initial Consultation with Fleur personally. Your full history heard, your systems assessed, your path forward mapped.
£150 · credited toward your programme if you continue
Book your initial consultation