The Methylation Doctor
I'm Dr Jean-Marc Sobczyk, a GMC-registered GP and naturopathic physician with a special interest in methylation and MTHFR. For more than 25 years I've worked on the symptoms that standard testing calls unremarkable: the fatigue, the fertility struggles, the gut and mood problems that never quite get explained. The answer is usually a mechanism nobody has looked for yet.
MD · ND
Dual-trained in conventional medicine (Université Paris VI) and naturopathic medicine (SCNM)
25+ years
Clinical practice across France, Switzerland, Beverly Hills and London
Genomic
Functional and genomic testing brought in where standard bloodwork stops
Mayfair
GMC 6148690. Seeing patients at Hooke, 86 Brook Street, London W1K 5AY, and online worldwide
Image · 16:7 full-width band — consulting room at Hooke, or Mayfair exterior
The Switch Sequence
Methylation protocols most often fail because they start at the end. Push methyl donors into an inflamed gut or a high toxic load and people feel worse, not better. This sequence runs the stages in the order the biochemistry actually requires.
01
Genomic panel alongside homocysteine, active B12, RBC folate, RBC magnesium and the wider methylation markers, so we are working from your biochemistry rather than from a variant on its own.
02
The gut barrier and microbiome come first. Folate and B12 absorption depend on a gut that works, and ongoing inflammation drives methylation demand upward faster than any supplement can meet it.
03
Toxic load. Mould and mycotoxins, metals and environmental exposures consume methylation capacity before anything else can use it, which is why they are dealt with before donors are introduced.
04
Cofactors. Riboflavin, B6, magnesium, zinc and choline are the inputs these enzymes need before methyl donors can be processed at all. Most of the intolerance people report traces back to this stage being skipped.
05
Methyl donors, introduced last and titrated to response, with homocysteine as the treatment endpoint rather than the variant you happen to carry.
Testing
A genotype tells you what is possible. These tell you what is happening. Which of them get run depends on your presentation, but this is the territory.
Homocysteine
The primary treatment endpoint, not the genotype
Active B12
Holotranscobalamin, rather than serum B12 alone
RBC Folate
Cellular status, not a snapshot of recent intake
RBC Magnesium
Targeted well above the bottom of the reference range
MTHFR C677T & A1298C
The two variants that actually alter enzyme efficiency
COMT
Catecholamine clearance, and tolerance of methyl donors
MTR & MTRR
The B12-dependent step that recycles homocysteine
Folate transport
How folate is carried into cells, not just how much there is
Stool & breath testing
Microbiome, dysbiosis and SIBO, assessed rather than assumed
Mycotoxins
Where a water-damaged building is in the picture
Inflammatory markers
The load that drives methylation demand upward
Cofactor status
Riboflavin, B6, zinc and choline, before any donor is introduced
Panel composition varies by presentation. Adjust this list to match what you actually run in clinic.
What I Treat
Different presentations, the same approach: find the mechanism, then treat it in sequence.
Genomic testing and treatment for MTHFR variants and methylation dysfunction, the biochemical thread running underneath several apparently unrelated complaints.
Fatigue unrelieved by sleep · low mood and anxiety · elevated homocysteine · poor tolerance of B vitamins · brain fog
A structured protocol for dysbiosis, SIBO and the downstream effects of a compromised gut barrier, including the absorption problems that undermine everything built on top of them.
Bloating and distension · IBS-type symptoms · SIBO · food reactivity · irregular bowel habit
The genomic and metabolic factors behind unexplained infertility and recurrent loss that a standard fertility workup is not designed to screen for.
Unexplained infertility · recurrent pregnancy loss · egg and sperm quality · failed cycles with no cause given
Chronic inflammatory response syndrome from water-damaged buildings and mould exposure, assessed and treated as an exposure problem rather than a psychological one.
Symptoms that ease away from home · chronic sinus congestion · air hunger · cognitive slowing · unusual sensitivity to smells
Proactive, biomarker-driven care aimed at healthspan rather than at the absence of a diagnosis, for people who are well and intend to stay that way.
Biological age testing · cardiometabolic risk · cognitive decline risk · healthspan planning
I don't treat conventional and functional medicine as opposing camps. I use conventional diagnostics where they are the right tool, and bring in functional and genomic testing where conventional testing runs out of answers.
Training & Practice
Medical degree from Université Paris VI and a naturopathic doctorate from the Southwest College of Naturopathic Medicine, followed by hospital medicine in France and Switzerland, integrative practice in Beverly Hills, residential care at the Kusnacht Practice, and now private practice at Hooke in Mayfair.
Where the evidence is still emerging, I say so and weigh it accordingly, case by case. That caveat is part of the method, not a disclaimer attached to the end of it.
More about meThe Community
For people working through this themselves, built on the same framework I use in clinic. Free membership includes the full Foundations archive.
Explore the HubCommon Questions
Do I need an MTHFR result before booking?
No. Most people arrive with symptoms and no genomic data at all. Testing is the first stage of the sequence for exactly that reason, and a result you already have is a starting point rather than a prerequisite.
I tried methylfolate and felt worse. Does that rule this out?
It usually means the opposite. Reacting badly to methyl donors is one of the more common reasons people are referred on, and it generally points to an earlier stage being skipped: unresolved gut inflammation, an unaddressed exposure, or missing cofactors. The sequence exists to prevent that.
Does a genetic variant amount to a diagnosis?
It does not, and I would be cautious of anyone who tells you otherwise. A variant describes a tendency, not a state. What it is doing in you is a question answered by your biochemistry, which is why homocysteine and the related markers, rather than the genotype, are what I treat to.
Will you work alongside my own doctor?
Yes, and I would prefer to. This is not a replacement for primary or secondary care, and where findings are clinically relevant to your ongoing care I will write to your primary care doctor or specialist.
What does treatment actually involve?
An initial consultation reviewing your history, symptoms and any results you already hold; testing where it will change the plan; then a protocol worked through in stages, with review points built around the markers rather than around a fixed calendar.
Consultations are held at Hooke, 86 Brook Street, Mayfair, London W1K 5AY, and online worldwide.
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