Fertility Supplements: Which Ones Do You Really Need?

Fertility supplements are a big business, and they’re aimed at a particularly vulnerable audience: women who want to conceive and want to give their baby the best possible start. Many have already faced difficulties getting pregnant, and some have been through miscarriage or other painful experiences along the way.

It’s completely natural to want to be sure you haven’t missed anything that could lower your chances of conceiving or leave your baby short of something important. But this is exactly where the confusion starts. Shelves and websites are full of ‘fertility blends’ packed with dozens of ingredients, and every friend seems to swear by a different one. Add advice from your GP, your fertility clinic and social media, and it’s easy to end up more confused than when you started.

But what does the evidence actually say? In reality, very few supplements are well supported by research and genuinely needed by most women. Some are useful only in specific situations, and others simply haven’t shown enough benefit to justify recommending them. Let’s have a look at each one.

Folic acid: the one supplement you need

Folic acid is the only supplement recommended for every woman planning a pregnancy, however good her diet. It’s the synthetic form of folate, which is found naturally in foods such as leafy green vegetables, pulses and citrus fruits.

Taking folic acid significantly reduces the risk of neural tube defects such as spina bifida. The neural tube closes in the first few weeks of pregnancy, often before you even know you’re pregnant, so starting early matters. A supplement is needed because diet alone can’t be relied on to reach protective levels.

The UK recommendation

400 mcg a day, ideally from the moment you start planning a pregnancy (or around three months before), continuing until 12 weeks.

Who needs a higher dose?

A higher dose of 5 mg is prescribed by a doctor in specific situations, such as a previous pregnancy affected by a neural tube defect, diabetes, or certain medications. Under the latest National Institute for Health and Care Excellence guidance (NICE, 2025), a higher body weight on its own is no longer a reason for the higher dose.

Folic acid or methylfolate?

Many supplements contain methylfolate (5-MTHF), the “active” form of folate. It’s often marketed as the better choice for women with a variant in the MTHFR gene (often called the “MTHFR mutation”). This variant is very common and slows down the conversion of folic acid into its active form.

It’s worth clarifying that women with this variant still use folic acid effectively, just more slowly. Protection against neural tube defects has also been proven in studies using folic acid, which is why it remains the official recommendation. If your supplement contains methylfolate, ask your doctor or dietitian whether you should add folic acid as well.

Don’t forget vitamin B12

Folate and vitamin B12 work together. If you’re low in B12, folate supplements, particularly at high doses, can mask the deficiency. They correct the anaemia that shows up on blood tests, but the B12 deficiency is still there and can affect the nervous system. It’s worth having your B12 checked before pregnancy, especially if you follow a plant-based diet, take metformin, or have a digestive condition.

Vitamin D: usually essential, especially in winter

From October to March, the sun in the UK isn’t strong enough for your body to make enough vitamin D. That’s why the NHS recommends at least 10 mcg (400 IU) a day before conception and throughout pregnancy.

For many women, though, this dose isn’t enough, especially if you get little sun exposure, have darker skin or a higher body weight. The higher doses often used, such as 1,000–2,000 IU, are safe and well below the upper safe limit, which also applies in pregnancy. The right dose for you is best guided by a simple blood test.

Iodine: the often-overlooked nutrient

Iodine is essential for your baby’s brain development, and your needs increase during pregnancy. In the UK, many women have borderline levels without realising it, so it’s worth making sure you’re getting enough from the time you start planning a pregnancy. The good news is that it’s easy to cover, through your diet or a suitable supplement.

The main sources of iodine are dairy, fish and eggs. If you rarely eat dairy or fish, choose a pregnancy supplement that contains iodine (around 150 mcg). Avoid seaweed (kelp) supplements, as their iodine content is unpredictable. It may be too low to meet your needs, or so high that it affects thyroid function, both yours and, once you conceive, your baby’s. If you have a thyroid condition, speak to your doctor before taking an iodine supplement.

Do you need a preconception multivitamin?

If you’re preparing for pregnancy, a multivitamin isn’t essential, especially if you eat a varied diet and already take folic acid and vitamin D. It can, however, be a practical option if your diet is limited, and a useful safety net if you’re not sure your diet covers everything. Most pregnancy multivitamins are also suitable for the months before conception.

If you decide to take one, check that it contains:

• 400 mcg folic acid and at least 10 mcg vitamin D
• iodine (around 150 mcg)
• vitamin A preferably as beta-carotene, not retinol. Vitamin A is essential, but in high amounts in its retinol form it can increase the risk of birth defects. That’s why the NHS advises women who are trying to conceive or are pregnant to avoid supplements containing retinol, as well as cod liver oil and liver. Beta-carotene, the plant form found in foods such as carrots and leafy greens, is safe, because your body only converts as much into retinol as it needs. Most pregnancy supplements use beta-carotene for this reason. If yours isn’t specifically designed for pregnancy, check the label to ensure it contains a safe amount.

Preconception multivitamins usually include other nutrients too, such as B12 and iron, in amounts that cover everyday needs. If you’re already deficient, however, these amounts are usually not enough to correct it. If you’re at higher risk, for example if you have heavy periods, follow a plant-based diet, take metformin or have a digestive condition, ask your doctor to check your levels, so that you can take a targeted supplement if needed.

Omega-3: fish comes first

Oily fish such as salmon, sardines and mackerel, eaten once or twice a week, is the best way to get the omega-3 fats DHA and EPA, along with many other valuable nutrients. DHA is a key building block of your baby’s developing brain, and EPA and DHA appear to reduce the risk of premature birth. The evidence on omega-3 and egg quality, however, is still preliminary.

If you don’t eat fish, a fish oil or algal oil supplement is a sensible option. As explained above, cod liver oil should be avoided before and during pregnancy. If you do decide to take an omega-3 supplement, choose one designed for preconception or pregnancy. These usually provide 200–300 mg DHA, in line with European Food Safety Authority (EFSA) recommendations for pregnancy, and don’t contain vitamin A.

Choline: a nutrient getting more attention

Choline is essential for the development of your baby’s brain and nervous system. Emerging research is encouraging, but there’s no official UK recommendation for supplements yet. Eggs are the richest source, and choline is also found in meat, fish, dairy and pulses. Most pregnancy supplements contain little or no choline, so for most women diet is the main way to get enough. If you rarely eat eggs or meat, or follow a plant-based diet, a choline supplement may be worth considering. Discuss it with your doctor or dietitian.

Inositol and PCOS

Myo-inositol is very popular among women with PCOS (now also known as PMOS), many of whom are concerned about their fertility. The 2023 international PCOS guidelines don’t recommend it for everyone, but they say it can be tried based on each woman’s preferences. Myo-inositol may improve some metabolic markers, such as insulin levels and triglycerides, and side effects are usually mild. For ovulation and fertility, however, the evidence isn’t yet strong enough.

If you’re already taking it and have noticed benefits, you can carry on, but let your doctor know when you’re planning a pregnancy or starting fertility treatment. And remember that inositol can complement, but not replace, diet, physical activity and medical care, which remain the foundation of PMOS management.

CoQ10, DHEA and “egg quality” supplements

• Coenzyme Q10 (CoQ10): Small studies in women undergoing IVF, mainly those over 35 or with low ovarian reserve, suggest a possible improvement in pregnancy rates. There’s no proven benefit for live births, and the quality of the evidence is low. It may be worth discussing with your clinic, but it isn’t essential.
• DHEA (dehydroepiandrosterone): This is a hormone, not a food supplement. The European Society of Human Reproduction and Embryology (ESHRE) doesn’t recommend it as an add-on in IVF. Don’t take it without medical advice.
• Melatonin: Best known as the hormone that regulates sleep, melatonin also has antioxidant properties. Studies in women having IVF suggest it may increase clinical pregnancy rates, but not live births, and studies are small and of low quality. A recent analysis concluded that the evidence remains inconsistent. In the UK, melatonin is prescription-only. If it’s suggested to you, discuss it with your doctor or fertility clinic.

If you’ve had recurrent miscarriages

If this is your experience, it’s completely understandable to want to do everything humanly possible to avoid going through it again, and to have a successful pregnancy. The European Society of Human Reproduction and Embryology (ESHRE, 2022) guidelines state that:

• Folic acid at the standard dose is still recommended, but it hasn’t been shown to prevent miscarriage.
• High-dose folic acid isn’t recommended unless there’s a specific medical reason.
• Vitamin D can be considered as part of general preconception care.

No supplement has been proven to prevent miscarriage, so be wary of products that claim to. Investigation by a specialist clinic is the most important step. Nutrition plays a complementary role, for example in supporting thyroid function, blood sugar control and correcting any nutritional deficiencies.

What about your partner?

Fertility involves both partners. Around half of infertility cases involve a male factor. Sperm take around three months to develop, so any changes to diet and lifestyle are worth starting early.

What the research says about supplements:

• A large randomised controlled trial found that folic acid and zinc did not improve sperm quality or live birth rates.
• A 2022 Cochrane review looked at antioxidant supplements commonly found in male fertility products, such as vitamins C and E, zinc, selenium, CoQ10 and L-carnitine. It found a possible benefit, but with very low certainty, and when lower-quality studies were removed, the benefit was no longer confirmed.

What really makes a difference for your partner is a Mediterranean-style diet, stopping smoking, cutting down on alcohol, a healthy weight and avoiding excess heat (such as saunas or a laptop on the lap). Any nutritional deficiencies can be treated in a targeted way, and a simple multivitamin can be considered if you both feel there may be gaps in his diet.

How to choose a good fertility supplement

In the UK, as in many other countries, supplements are regulated as foods, not medicines. This means they don’t have to prove they work before going on sale.

Choose products that:

• are independently tested (third-party tested)
• clearly state the form and dose of each ingredient
• don’t use “proprietary blends”. These don’t show the amount of each ingredient, so you can’t tell whether a dose is too low to help or whether the blend contains ingredients, such as herbs, that aren’t recommended before or during pregnancy
• don’t make exaggerated promises

And remember: more, natural or organic doesn’t mean better.

Key takeaways

When it comes to fertility supplements, folic acid is essential for everyone. Vitamin D is almost always needed if you live in the UK or another country with limited sunshine. Iodine and omega-3 are worth taking if your diet doesn’t include good sources. Beyond that, what your body needs depends on your own circumstances: your medical history, blood test results, diet and any medications you take. And most importantly: supplements complement a balanced diet; they don’t replace it.

Would you like personalised advice?

If you’d like to talk about which supplements could help you, or more broadly which diet and lifestyle changes could support your journey to pregnancy, take a look at my Fertility & Pregnancy Nutrition Programme. If you have PCOS, see my PCOS / PMOS Nutrition Programme.

I also work alongside fertility clinics, including JIVA Fertility, to support patients’ nutrition before and during treatment.

You can also book a free 15-minute discovery call to talk about how I can help. Sessions are online, in English or Greek.

Also in this series: Menopause Supplements & Vitamins: Which Do You Really Need?

References

1. NICE. Maternal and child nutrition: nutrition and weight management in pregnancy, and nutrition in children up to 5 years (NG247). 2025.
2. MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991;338:131–137.
3. Centers for Disease Control and Prevention. MTHFR gene variant and folic acid facts. 2025. https://www.cdc.gov/folic-acid/data-research/mthfr/
4. EFSA Panel on Nutrition, Novel Foods and Food Allergens. Scientific opinion on the tolerable upper intake level for vitamin D. EFSA Journal. 2023;21(8):8145.
5. Bath SC, et al. Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from ALSPAC. Lancet. 2013;382:331–337.
6. Middleton P, et al. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018;11:CD003402.
7. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on dietary reference values for fats, including polyunsaturated fatty acids. EFSA Journal. 2010;8(3):1461.
8. EFSA Panel on Dietetic Products, Nutrition and Allergies. Dietary reference values for choline. EFSA Journal. 2016;14(8):4484.
9. Caudill MA, et al. Maternal choline supplementation during the third trimester of pregnancy improves infant information processing speed: a randomized, double-blind, controlled feeding study. FASEB J. 2018;32(4):2172–2180.
10. Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023.
11. Fitz V, et al. Inositol for polycystic ovary syndrome: a systematic review and meta-analysis to inform the 2023 update of the International Evidence-based PCOS Guidelines. J Clin Endocrinol Metab. 2024;109(6):1630–1655. doi:10.1210/clinem/dgad762
12. Showell MG, et al. Antioxidants for female subfertility. Cochrane Database Syst Rev. 2020;8:CD007807.
13. Florou P, et al. Does coenzyme Q10 supplementation improve fertility outcomes in women undergoing assisted reproductive technology procedures? A systematic review and meta-analysis. J Assist Reprod Genet. 2020;37:2377–2387.
14. ESHRE Add-ons working group, Lundin K, et al. Good practice recommendations on add-ons in reproductive medicine. Hum Reprod. 2023;38(11):2062–2104. doi:10.1093/humrep/dead184
15. Hu KL, et al. Melatonin application in assisted reproductive technology: a systematic review and meta-analysis of randomized trials. Front Endocrinol. 2020;11:160. doi:10.3389/fendo.2020.00160
16. Wu Y, et al. Melatonin improved the outcomes of women with ART: a systematic review and meta-analysis of randomized trials. Front Reprod Health. 2025;7:1680984. doi:10.3389/frph.2025.1680984
17. ESHRE Guideline Group on RPL, Bender Atik R, et al. ESHRE guideline: recurrent pregnancy loss: an update in 2022. Hum Reprod Open. 2023;2023(1):hoad002.
18. Schisterman EF, et al. Effect of folic acid and zinc supplementation in men on semen quality and live birth among couples undergoing infertility treatment: a randomized clinical trial. JAMA. 2020;323(1):35–48.
19. de Ligny W, et al. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022;5:CD007411. doi:10.1002/14651858.CD007411.pub5

This article is for educational purposes only and does not replace personalised medical or dietary advice. Before starting any supplement, especially if you have a medical condition, take medication or are having fertility treatment, please speak to your doctor.