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What Your Surgeon Isn't Telling You · Series · Fertility · IVF

What Your Fertility Clinic
Isn't Telling You

A single IVF cycle costs upward of £5,000. The probability of success is substantially influenced by egg quality, sperm quality, uterine receptivity, and implantation capacity — all of which have documented nutritional dependencies. CoQ10, methylfolate, zinc, selenium, vitamin D, omega-3, and inositol are specific, measurable, correctable nutritional factors that influence IVF outcomes. No fertility clinic is assessing them before your cycle begins.

Stephen DuncanFDN-P MSc BSc · 37 years clinical practice
Reading time13 minutes
SeriesWhat Your Surgeon Isn't Telling You · Part 2
What Your Surgeon Isn't Telling You · Part 2

This series applies functional nutritional assessment to medical procedures where the biological outcome is substantially determined by nutritional status that nobody is measuring. Part 1 covered surgical and sports injury recovery. This post covers IVF and fertility. Subsequent posts will cover dental implants and oncology support.

I want to start with a number that should stop anyone in their tracks.

The live birth rate per IVF cycle in the UK for women under 35 is approximately 32%. For women aged 35–37 it drops to 25%. For women aged 38–39 it falls to 19%. For women aged 40–42, 11%. These are the Human Fertilisation and Embryology Authority (HFEA) figures — the most reliable dataset available.

These numbers mean that for the majority of women undergoing IVF, a single cycle will not result in a live birth. Many women go through multiple cycles — at £5,000 or more each — before achieving a pregnancy, or before deciding the emotional and financial cost is no longer sustainable.

The fertility industry knows these numbers. They are published, discussed, and disclosed. What is not disclosed — and not assessed — is the degree to which these probabilities are modified by individual nutritional status. Because the biological processes that determine IVF success — egg quality, follicular development, fertilisation, embryo development, implantation, early pregnancy maintenance — are all enzymatic processes requiring specific nutritional cofactors. And those cofactors vary enormously between individuals.

A woman going into an IVF cycle with optimal CoQ10 status, adequate methylfolate, replete zinc and selenium, optimal vitamin D, and sufficient omega-3 is not in the same biological position as a woman who is insufficient across all of these. The clinic treats them identically. The biology does not.

Egg quality — the primary determinant of IVF success

Egg quality is arguably the single most important factor in IVF success — more important than the stimulation protocol, more important than the laboratory conditions, and more important than most of the variables that fertility clinics spend time and money optimising.

What determines egg quality? The oocyte is the largest cell in the human body and one of the most metabolically demanding. It contains more mitochondria than any other cell type — because the energy requirements of meiosis (the cell division that produces the egg) and early embryonic development are extraordinary. The mitochondria in the egg must power the entire process of fertilisation and the first several days of embryonic development before the embryo's own genome activates.

Mitochondrial function is the key variable. And mitochondrial function is nutritionally dependent in specific and correctable ways.

CoQ10 (ubiquinol) is the rate-limiting cofactor for the mitochondrial electron transport chain — the process by which mitochondria produce ATP. Without adequate CoQ10, mitochondrial energy production is impaired. In the context of the oocyte, this means reduced ATP availability for meiosis, reduced energy for early embryonic development, and higher rates of chromosomal segregation errors — the primary cause of failed fertilisation, failed implantation, and early miscarriage.

CoQ10 levels in the body decline with age — which is one of the biochemical mechanisms underlying age-related decline in egg quality and IVF success rates. This is not simply an age story. It is a mitochondrial energy story — and CoQ10 is correctable.

Clinical evidence for CoQ10 supplementation in fertility is growing. A randomised controlled trial published in Fertility and Sterility (Bentov et al.) showed significant improvements in ovarian response, fertilisation rates, and embryo quality in women supplemented with CoQ10 compared to controls. The doses used were 600mg daily of ubiquinol — substantially higher than the 100–200mg found in most general supplements. Timing matters too: CoQ10 takes approximately 90 days to accumulate in ovarian tissue — the same timeframe as the follicular development cycle. Starting supplementation at least three months before a cycle is essential.

The nutrients that matter — and the evidence behind them

CoQ10 (Ubiquinol)
Mitochondrial energy · Egg quality
Rate-limiting cofactor for ATP production in the oocyte. Declines with age. Dose: 400–600mg daily of ubiquinol (not ubiquinone — ubiquinol is the reduced, active form and is significantly better absorbed). Start 3 months before cycle — follicular development takes 90 days and CoQ10 needs to accumulate in ovarian tissue.
RCT evidence: improved ovarian response, fertilisation rates, and embryo quality (Bentov et al., Fertility and Sterility)
Methylfolate (5-MTHF)
DNA methylation · Neural tube formation · Embryo development
Folate is essential for DNA synthesis and methylation — the epigenetic process that regulates gene expression in the developing embryo. Folic acid (the synthetic form in most supplements and now added to flour) requires conversion to active methylfolate via MTHFR. Approximately 40% of the population have MTHFR variants reducing this conversion. These individuals need pre-formed methylfolate (5-MTHF), not folic acid. Getting this wrong is not a minor issue — inadequate active folate increases miscarriage risk and embryonic developmental abnormality risk.
MTHFR testing available via blood spot — essential for anyone with recurrent miscarriage or failed implantation
Vitamin D
Uterine receptivity · Implantation · Immune tolerance
Vitamin D receptors are present in the uterine endometrium. Adequate vitamin D is required for endometrial receptivity — the window of implantation during which the embryo can successfully attach. Studies consistently show higher IVF success rates in vitamin D-sufficient women versus deficient women. Vitamin D also modulates the immune response to implantation — the body must tolerate a semi-foreign embryo, and vitamin D plays a specific role in this immune tolerance. Target: 100–150 nmol/L serum, not merely the NHS "adequate" threshold of 50 nmol/L.
Meta-analysis: vitamin D-sufficient women had 34% higher clinical pregnancy rates per IVF cycle (Łukaszuk et al.)
Selenium
Antioxidant protection · Thyroid function · Embryo development
Selenium is essential for glutathione peroxidase — the primary antioxidant enzyme in the follicular fluid that protects the developing oocyte from oxidative damage. Follicular fluid selenium concentration correlates with fertilisation rates. Selenium is also critical for thyroid function (via iodothyronine deiodinase), and thyroid status directly affects fertility. UK soils are severely selenium-depleted — UK dietary selenium intake is among the lowest in Europe. Standard blood serum selenium is an insensitive marker; functional assessment is more reliable.
Lower follicular fluid selenium associated with poorer embryo quality and lower fertilisation rates
Zinc
Oocyte maturation · Fertilisation · Embryo development
Zinc is essential at every stage of female fertility — follicle development, oocyte maturation (the "zinc spark" at fertilisation is a documented phenomenon — zinc is released in a flash at the moment of sperm-egg fusion), and early embryo development. Zinc deficiency impairs all three. In male fertility, zinc is essential for sperm production, sperm motility, and sperm DNA integrity. It is one of the most important fertility nutrients for both partners.
The zinc spark at fertilisation is one of the most visually dramatic demonstrations of nutrient biology in reproduction
Omega-3 (EPA and DHA)
Endometrial blood flow · Embryo development · Inflammation
DHA is a structural component of cell membranes — including those of the oocyte and developing embryo. Adequate DHA supports membrane fluidity and function during fertilisation and early development. Omega-3s also support endometrial blood flow (via prostaglandin E1 and prostacyclin pathways) and reduce the inflammatory burden that can impair implantation. Higher omega-3 status is associated with better IVF outcomes in multiple studies.
Higher omega-3 status associated with improved embryo morphology and higher live birth rates
Inositol (Myo and D-chiro)
Ovarian function · Insulin sensitivity · PCOS
Inositol is a carbocyclic sugar involved in insulin signalling and FSH receptor function in the ovary. Myo-inositol specifically improves ovarian response to FSH stimulation and oocyte quality — particularly relevant in women with PCOS or insulin resistance. The combination of myo-inositol (4g) and D-chiro-inositol (400mg) in a 40:1 ratio has emerging evidence for improving egg quality, reducing FSH requirements in stimulation cycles, and improving pregnancy rates.
Multiple RCTs showing improved oocyte quality and pregnancy rates, particularly in PCOS — the evidence base for inositol in fertility is among the strongest of any nutritional intervention
N-Acetylcysteine (NAC)
Antioxidant · Glutathione precursor · PCOS and endometriosis
NAC is the most bioavailable precursor to glutathione — the cell's primary antioxidant. Oxidative stress in follicular fluid is a significant driver of poor egg quality. NAC reduces follicular oxidative damage and has specific evidence in endometriosis (reducing the inflammatory burden that impairs fertility) and PCOS (improving insulin sensitivity and ovarian function). 600mg twice daily is a commonly used dose in fertility contexts.
RCT evidence in both PCOS and endometriosis for improved pregnancy rates

The methylation story — why MTHFR matters more than most people know

The MTHFR gene encodes methylenetetrahydrofolate reductase — the enzyme that converts dietary folate into the active form (5-methyltetrahydrofolate, or 5-MTHF) required for the methylation cycle. The methylation cycle is not a peripheral biochemical pathway. It is fundamental to DNA synthesis, DNA repair, gene expression, and the epigenetic programming of the developing embryo.

The two most common MTHFR variants — C677T and A1298C — are present in significant proportions of the population. C677T in its homozygous form reduces MTHFR enzyme activity by approximately 70%. Heterozygous C677T reduces activity by approximately 35%. These are not rare mutations. They are common polymorphisms with real consequences for anyone relying on folic acid supplementation to support fertility and early pregnancy.

The problem is that the standard advice — "take 400µg of folic acid before and during pregnancy" — assumes normal MTHFR function. For the 40% of people with reduced MTHFR activity, folic acid is poorly converted and may actually accumulate as unmetabolised folic acid — which has its own concerns including potential interference with folate receptor function and with the immune response to implantation.

The correct supplementation for MTHFR variants is methylfolate (5-MTHF) — the pre-activated form that bypasses the MTHFR step entirely. This is not an alternative medicine position. It is biochemistry. And yet most fertility clinics — and most GPs advising on pre-conception supplementation — are still recommending standard folic acid without asking whether the patient can actually convert it.

Homocysteine is the metabolic marker most relevant here. Elevated homocysteine is a downstream consequence of impaired methylation — and is independently associated with increased miscarriage risk, implantation failure, and adverse pregnancy outcomes. It is testable from a standard blood draw. It is not routinely checked in fertility workups.

The thyroid connection

Thyroid function is directly relevant to fertility — and is consistently under-investigated in both NHS and private fertility workups.

TSH above 2.5 mIU/L is associated with reduced IVF success rates, increased miscarriage risk, and impaired embryo development. The British Thyroid Association guidelines recommend TSH below 2.5 in women trying to conceive. Many NHS fertility clinics use the standard laboratory upper limit of 4.0 as their threshold — which means a woman with TSH of 3.8 may be told her thyroid is fine while carrying a meaningful fertility risk.

More importantly, thyroid antibodies — TPO and TgAb — are not routinely checked in fertility workups. Women with elevated thyroid antibodies (Hashimoto's) have significantly higher miscarriage rates and lower IVF success rates even when TSH is normal, because the autoimmune inflammation affects the uterine immune environment and endometrial function. Treating the antibody picture — with selenium, vitamin D, and where appropriate thyroid hormone support — improves outcomes. But you have to know the antibodies are elevated first.

Male fertility — the forgotten half of the equation

Approximately 40–50% of fertility challenges involve a male factor. And yet the nutritional support conversation in fertility is almost entirely female-focused.

Male Fertility — Key Nutritional Factors

Sperm take approximately 74 days to develop. The nutritional environment during sperm production determines sperm count, motility, morphology, and DNA fragmentation. Sperm DNA integrity is increasingly recognised as a critical factor in IVF success and early pregnancy loss — and is substantially influenced by oxidative stress, which is nutritionally modifiable.

Zinc
Essential for testosterone production, sperm production, sperm motility, and sperm DNA packaging. Seminal plasma contains the highest zinc concentration of any body fluid. Zinc deficiency is a primary driver of poor sperm parameters.
CoQ10
Sperm mitochondria — which power the flagellar movement that drives motility — are CoQ10-dependent. Low CoQ10 is associated with reduced sperm motility. RCT evidence shows improved motility and count with 200–400mg ubiquinol daily.
Selenium
Essential for spermatogenesis and the structural integrity of the sperm flagellum. Selenoprotein P in seminal plasma protects sperm from oxidative damage. UK selenium insufficiency directly impairs male fertility.
Vitamin C and E
Primary antioxidants in seminal plasma protecting sperm DNA from oxidative fragmentation. Sperm DNA fragmentation above 25% significantly reduces IVF success rates. Antioxidant supplementation reduces fragmentation — measurable on sperm DNA fragmentation testing.
L-Carnitine
Essential for transporting fatty acids into sperm mitochondria for energy production. Epididymal carnitine concentrations are among the highest in the body. L-carnitine supplementation improves sperm motility in multiple RCTs.
Omega-3 (DHA)
DHA is a structural component of the sperm head membrane. Low sperm DHA is associated with poor morphology and reduced fertility. Fish oil supplementation improves sperm DHA content and several sperm parameters.

The inflammatory load — and why gut health matters for fertility

Systemic inflammation is an underappreciated driver of fertility challenges — both male and female.

Elevated inflammatory cytokines impair follicular development, reduce endometrial receptivity, and create a uterine immune environment less tolerant of implantation. The immune tolerance of implantation is a finely regulated process — the maternal immune system must accept a semi-foreign embryo without rejecting it. Chronic systemic inflammation dysregulates this process.

The gut microbiome is directly relevant here. The uterine microbiome — yes, the uterus has its own microbiome — is influenced by the gut microbiome, and its composition affects implantation success. A uterine microbiome dominated by Lactobacillus species is associated with higher IVF success rates. Dysbiotic uterine microbiomes are associated with implantation failure and recurrent miscarriage. The gut-uterine connection is real and clinically actionable.

Endometriosis — present in approximately 10% of women of reproductive age and significantly overrepresented in women with fertility challenges — is fundamentally an inflammatory condition. The inflammatory burden of endometriosis creates a hostile uterine environment for implantation and impairs egg quality via oxidative stress in follicular fluid. Nutritional anti-inflammatory support — omega-3, NAC, curcumin, vitamin D — is not a substitute for surgical management of endometriosis where indicated, but it addresses the inflammatory biology that drives the fertility impairment.

The optimal preparation window

Pre-IVF Nutritional Optimisation — Timeline
6 months before
Nutritional assessment — blood chemistry covering CoQ10 (if available), vitamin D, zinc, selenium, folate, B12, homocysteine, thyroid panel (TSH, free T3, free T4, TPO and TgAb antibodies), CRP, fasting insulin. MTHFR testing if recurrent miscarriage or failed implantation history. Begin correcting identified deficiencies — this timeframe allows optimal CoQ10 accumulation in ovarian tissue.
3–6 months before
Core supplementation protocol in place: CoQ10 400–600mg ubiquinol daily, methylfolate 400–800µg (not folic acid if MTHFR variants identified), vitamin D to optimise serum levels, zinc 25mg, selenium 100–200µg, omega-3 2–4g EPA/DHA, inositol myo/d-chiro 40:1 ratio where indicated (PCOS or insulin resistance). NAC 600mg twice daily where oxidative stress or endometriosis is a factor. Male partner on equivalent antioxidant protocol.
3 months before
Gut assessment where indicated — particularly if there is a history of gut symptoms, food reactivity, recurrent infections, or previous implantation failure. GI-MAP reveals dysbiosis and permeability that drives systemic inflammation. Dietary optimisation — adequate protein, anti-inflammatory food base, removal of identified IgG reactive foods.
During stimulation
Continue antioxidant protocol. Adequate protein and micronutrient intake during stimulation supports follicular development. Stay well hydrated — OHSS risk management partly involves adequate fluid and electrolyte intake.
Transfer and post-transfer
Vitamin D, methylfolate, and omega-3 are particularly important in the implantation window. Progesterone support (where prescribed by clinic) is complemented by nutritional anti-inflammatory support. Avoid high-intensity exercise in the peri-transfer period — moderate movement supports endometrial blood flow without stress hormone activation.
Early pregnancy
Continue methylfolate, vitamin D, omega-3, and zinc. Review full protocol with practitioner — some supplements are reduced or stopped in early pregnancy. Thyroid monitoring is essential — TSH should be maintained below 2.5 throughout first trimester.

What the fertility clinic does and doesn't do

I want to be clear about what I'm not saying. Fertility clinics provide excellent medical care — the stimulation protocols, the embryology expertise, the monitoring, the surgical skill involved in egg collection and transfer are all genuinely sophisticated and important. The HFEA regulatory framework is robust. The medical side of IVF is well done.

What is not done is the nutritional preparation of the biological environment in which the procedure occurs. This is not a criticism of individual clinicians — it reflects the training, the time constraints, and the clinical framework within which fertility medicine operates. Nutritional assessment is simply not part of the fertility workup as currently structured.

The consequence is that two women undergoing identical IVF protocols — same stimulation doses, same laboratory, same transfer technique — may have very different outcomes based on the nutritional foundation they bring to the process. The clinic treats them identically. The biology does not.

A woman investing £5,000 in an IVF cycle deserves to know that the biological environment she's investing in has been optimised. That optimisation is not part of the fertility clinic's offering. It should be part of her preparation.

The pre-conception window — natural conception too

Everything in this post applies equally to women trying to conceive naturally, not just those undergoing IVF. The nutritional determinants of egg quality, uterine receptivity, and implantation are the same regardless of whether fertilisation happens in a laboratory or a fallopian tube.

The advantage of addressing this nutritionally is that the improvements — in egg quality, in endometrial receptivity, in inflammatory load, in thyroid function — are real improvements to the biological substrate of conception. They don't just improve IVF outcomes. They improve the probability of natural conception, reduce miscarriage risk, and support early pregnancy development regardless of how fertilisation occurs.

The three-month pre-conception window — the 90 days that correspond to the follicular development cycle — is when this work is most impactful. It is also the window that most couples spend in a state of hopeful waiting rather than active biological preparation.

Relevant Investigation

Blood Chemistry — vitamin D, zinc, folate, B12, homocysteine, thyroid panel including antibodies, CRP, fasting insulin · DUTCH Plus — oestrogen, progesterone, cortisol pattern · GI-MAP — gut microbiome, inflammatory load, intestinal permeability · Methylation Profile — MTHFR and homocysteine in context

Planning IVF or trying to conceive?

The DH Clinical Concierge can help you understand what a pre-conception nutritional assessment would look like for your specific picture — no appointment needed to start.

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