Written by Dr Divpreet Sacha. Reviewed by Dr Katherine Joseph. 

Dr Divpreet Sacha is a UK-based GP specialising in fertility and preventative medicine. She works with Neko Health, a preventative health tech company focused on early detection and lifestyle medicine. Divpreet is the creator of the Fertility Foundations programme, an evidence-based online educational programme integrating lifestyle medicine, supplements, exercise, and medical pathways to support fertility. The programme was born from her own experience navigating IVF, miscarriage, and PCOS, to help individuals feel informed and empowered throughout their fertility journey.

If you've ever left a GP appointment with a recommendation for Folic Acid and Vitamin D and nothing else, you haven't been fobbed off. That genuinely is what the guidelines say. So, if you've then gone home, fallen down a research rabbit hole about CoQ10, Methylfolate, Zinc and antioxidants, and wondered why your GP didn't mention any of it - that's a completely fair question.

The answer is less about what your GP knows and more about how clinical guidelines work. NICE sets the standard, your local ICB adapts it and decides whether to fund it, and your GP is left trying to manage the gap between them in a 10-minute appointment.

What NICE Actually Recommends

NICE (National Institute for Health and Care Excellence) produces the clinical guidelines that GPs across England follow. They do this by providing guidance and recommendations for healthcare practitioners through evidence reviews, expert committees and consultations. For fertility, the key document is CG156, first published in 2013 and last updated in 2017. When it comes to nutrition, it is deliberately minimal.

Folic Acid

Women trying to conceive are advised to take 400mcg of Folic Acid daily, starting before conception and continuing to 12 weeks. A higher dose of 5mg is prescribed for women who have previously had a pregnancy affected by a neural tube defect, who are taking anti-epileptic medication, or who have diabetes. 

Vitamin D

Vitamin D warrants a separate mention: the standard 10 mcg daily recommendation comes from broader NHS public health guidance for all UK adults, not from the fertility-specific guideline.

Other nutrients

That, genuinely, is it. CoQ10, antioxidants, Zinc, Selenium, B12, Iron, the nuances of Methylfolate, none of it appears. Not because NICE has reviewed the evidence and found it wanting, but because it hasn't yet cleared the bar for NHS implementation. This bar includes the following criteria: being cost-effective for the NHS, showing a clear population-level benefit, settled evidence, and focusing on preventing deficiency. As many of the nutrients associated with improved fertility outcomes have growing evidence, or smaller study sizes, this means many have not made the NICE guidelines yet. 

The Difference Between Correcting a Deficiency and Optimising for Fertility

This is something I discovered the hard way, through my own fertility journey, despite being a GP.

NICE guidelines are built around correcting deficiencies and preventing disease. They're not designed to optimise. A Vitamin D level of 50nmol/L is considered normal by NHS reference ranges, but emerging research suggests higher levels may genuinely matter when you're trying to conceive. A prospective cohort study found that women with Vitamin D above 125 nmol/L had an estimated 35% increase in their per-cycle chance of conception compared to those with 75-100 nmol/L. In IVF settings, women in the highest Vitamin D categories consistently show better clinical pregnancy and live birth rates. The caveat: randomised trials of Vitamin D supplementation haven't consistently shown improved outcomes, which suggests that while Vitamin D status appears to matter, the best way to address it through supplementation is still being worked out.

Your GP can tell you your Vitamin D levels are fine. That doesn't necessarily mean it's optimal for what you're trying to do. The safe upper limit for Vitamin D supplementation in adults is 100mcg (4000 IU) per day according to UK guidance. Higher doses (up to 10,000 IU per day) may sometimes be prescribed for deficiency under medical supervision. While the NHS recommendations are often aimed at general population health, many fertility specialists recommend this higher, safe upper limit of 100mcg,  for those actively trying to conceive, especially if there is a known deficiency or during certain times of the year.

The same applies to Folate. For anyone taking a standard over-the-counter dose of 400 to 800 mcg, choosing Methylfolate rather than Folic Acid is generally considered safe. Methylfolate is the natural, active form already present in your body and in food. It may have practical advantages: it avoids the build-up of unmetabolised Folic Acid in the bloodstream, and for people with MTHFR gene variants affecting folate metabolism, it bypasses the conversion step entirely.

What the Research Is Actually Showing

Beyond Folate, there's a meaningful body of research on nutritional support for fertility that simply hasn't made it into NHS guidance yet. 

CoQ10

CoQ10 probably has the strongest evidence. It plays a key role in cellular energy production, which matters a great deal for egg maturation. Research reviews have reported improvements in ovarian response and the number of eggs retrieved in some groups of women, particularly those with reduced ovarian reserve, who supplemented with CoQ10. Something else worth knowing: not all CoQ10 supplements are the same. Patented MicroActive® CoQ10 has been shown to be absorbed 3.7 times more effectively than standard versions.

Vitamins B12 and B6

B12 and B6 are essential for methylation; the process your body uses to activate, repair and regulate cells, and this directly underpins egg quality. B12 deficiency is often missed, particularly in those who eat a plant-based diet or have gut absorption issues, and it isn't routinely screened for in a fertility context. Research combining Methylfolate with B12 has shown associations with better pregnancy and live birth rates in women going through assisted reproduction. 

Nutritional gaps are common

What all of this points to is a finding that comes up time and again in the research: people experiencing infertility may be more likely to have nutritional gaps; particularly in Vitamins C, D, B6, B12, Zinc and Selenium, and those gaps tend to be more pronounced in women over 35. The NHS framework is built to catch deficiencies in the general population. It was never designed to identify the subtler nutritional picture that can matter so much when you're trying to conceive.

What You Can Do

Use the NICE guidelines as the starting point, not the entire plan.

If your GP has prescribed high-strength 5mg folic acid, please don't substitute it without speaking to them first. That prescription exists for a specific clinical reason. For everyone else, a standard over-the-counter dose of Methylfolate is a perfectly reasonable choice.

If you want to go further with your nutritional picture, work with someone who can actually assess it. A specialist fertility nutritionist can make evidence-informed recommendations that simply aren't possible in a standard GP appointment. You don't need a diagnosis or a referral to start that conversation.

If you're looking at supplements, the details really do matter. Form, dose and how well something is absorbed are not small print; they are the difference between a product that reflects the research and one that doesn't. Methylfolate rather than Folic Acid if it's relevant to you. MicroActive® CoQ10 rather than a standard form. Methylcobalamin rather than the cheaper form of B12. The research is specific to these distinctions, and that specificity is worth paying attention to.

Understanding what NICE does and doesn't cover is the first step. The guideline is a floor. Your care doesn't have to stop there. And you don't have to figure it out alone. 

Key Takeaways

• NHS guidance is based on NICE guidelines, which prioritises preventing deficiencies at a population level, rather than optimising nutrient intake for fertility. Emerging areas of fertility nutrition research often involve smaller or earlier-stage studies, which means they take longer to translate into formal guidance.

• There is a growing body of research exploring the role of nutrients such as CoQ10, Vitamin B12 and Vitamin B6 in preconception health. Nutritional gaps are common in the UK population, and so supplements can fill nutritional gaps, when diet is unable to do so alone. 

• NICE guidance is an important starting point when thinking about reproductive health. However, there is further support available, via fertility specialists, appropriate supplementation, healthcare professionals, and more.