Diet and Fertility: Eating Well to Conceive

No food makes you fertile. Inserm (the French national health research institute) is clear on this: no study has shown that any specific diet or food prevents infertility. What does genuinely matter is the lifestyle of both future parents: weight, tobacco, alcohol and cannabis have proven effects, and a Mediterranean-style diet is associated with better outcomes in several studies. For the future mother, one step is non-negotiable: vitamin B9 (folate) as soon as you start planning a pregnancy. Here is what is proven, what is probable, and what is myth.

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What science really knows

In France, one couple in four trying to have a child is affected by infertility, according to Inserm, and 3.9% of children are now conceived through medically assisted reproduction. In about three quarters of cases, infertility has a male, female or mixed cause; in 10 to 15% of cases, it remains unexplained. Diet is therefore just one factor among others, well behind age and certain conditions (endometriosis, polycystic ovary syndrome).

The French National Authority for Health (HAS) sums up the state of the evidence in its document on planning a pregnancy: only obesity, alcohol, tobacco and psychoactive substances have demonstrated negative effects on the course of pregnancy and foetal development. For everything else, the data come mainly from observational studies, which show associations without proving cause. The main ones:

Study	Population	Main result
Chavarro et al., Obstetrics & Gynecology, 2007	17,544 American nurses followed for 8 years	Women closest to a « fertility » pattern (among other things: monounsaturated rather than trans fats, plant protein, low glycaemic index carbohydrates, plant-based iron) had a 66% lower risk of infertility due to ovulation disorders (relative risk 0.34). Five or more favourable lifestyle factors, including weight and physical activity: risk reduced by 69%.
Karayiannis et al., Human Reproduction, 2018	244 non-obese women undergoing their first IVF cycle in Athens	Among women furthest from the Mediterranean diet, the clinical pregnancy rate was 29.1% versus 50% among those closest to it, and live births 26.6% versus 48.8%.
Salas-Huetos et al., Human Reproduction Update, 2017	Review of 35 observational studies in men	Fish and seafood, poultry, cereals, fruit and vegetables were associated with better sperm; processed meat, sweet products, sugary drinks and alcohol were associated with poorer quality in some studies.
Fan et al., Scientific Reports, 2017	19 studies, 98,657 women	Among women who drink alcohol, fecundability (chance of conceiving per cycle) was reduced: relative risk 0.87 overall, 0.77 above 12.5 g of alcohol per day.
Sermondade et al., Human Reproduction Update, 2013	21 studies, 13,077 men	Higher risk of oligospermia or azoospermia with overweight (OR 1.11), obesity (OR 1.28) and severe obesity (OR 2.04).

The review by Gaskins and Chavarro (American Journal of Obstetrics and Gynecology, 2018) draws a cautious conclusion: a diet that favours seafood, poultry, wholegrain cereals, fruit and vegetables is linked to better fertility in women and better sperm in men. It also stresses that randomised trials are lacking, and that the diets of both partners are rarely studied together.

Vitamin B9 as soon as you plan a pregnancy

This is the only supplement recommended for all women considering pregnancy, and it is not there to help you get pregnant: it is there to protect the embryo. Inserm also warns against sites that present B9 as a fertility booster. Its role is to prevent neural tube closure defects (spina bifida, anencephaly), which affect nearly one pregnancy in 1,000 in France according to the HAS.

To be effective, prevention must start before conception. Hence the schedule set by the HAS: prescribe folic acid from the preconception consultation, at 400 µg per day, and continue until 12 weeks of amenorrhoea. An older HAS opinion specifies that you should start at least 4 weeks before conception. A dose of 5 mg per day is reserved for women at high risk (previous affected pregnancy, certain antiepileptic drugs). Yet in the 2021 French National Perinatal Survey, only 28.3% of women had started folic acid before pregnancy.

Your plate complements the tablet. Anses (the French food safety agency) sets an adequate intake of 600 µg of folate per day for women who may become pregnant, against 330 µg for other adult women. The best sources are green vegetables, pulses and nuts: according to Ciqual, 100 g of cooked spinach provides 125 µg of folate, 100 g of cooked chickpeas 84.4 µg, 100 g of cooked lentils 50.1 µg and 100 g of walnuts 120 µg. The glossary’s vitamin B9 entry explains its role in detail.

The Gaskins and Chavarro review also notes that taking folic acid, especially at doses higher than those used to prevent neural tube defects, is associated in studies with less infertility and fewer miscarriages. These are associations: they do not justify taking higher doses without a prescription.

Weight, the first modifiable lever

In women, Santé.fr (the French public health information portal) states that with moderate obesity, the risk of anovulation (absence of ovulation) is multiplied by 3 to 4. In men, a high BMI can impair sperm quality, which the Sermondade meta-analysis cited above confirms. Being significantly underweight is also a problem: in this case, as with obesity or anorexia, the HAS calls for an assessment and appropriate care.

If you are overweight, the HAS recommends increasing physical activity and following dietary advice. The aim is not a crash diet, but a sustainable balanced diet. To work out your starting point, use our BMI calculator and, if you want to lose weight, our guide to losing weight healthily. Your starting weight also matters later on: it determines the recommended weight gain during pregnancy.

Tobacco, alcohol, cannabis: stop beforehand, and together

Tobacco is one of the main factors that lower fertility. According to Santé.fr, the risk of infertility is doubled in female and male smokers alike, and smoking lengthens the time to conceive by about 4 to 6 months. In men, sperm are fewer in number and less mobile. Passive smoking also matters: the HAS mentions it explicitly.

Alcohol impairs fertility in men and women alike. The Fan et al. meta-analysis finds reduced fecundability even with light consumption (relative risk 0.89 up to 12.5 g of alcohol per day). The Gaskins and Chavarro review judges the effect of moderate drinking to be less solid than previously thought, but the question is quickly settled: since conception cannot be dated to the exact day and zero alcohol is the rule during pregnancy, the simplest thing is to stop as soon as you start trying.

Cannabis reduces sperm quantity, mobility and lifespan, and in women increases the risk of ovarian cysts and miscarriage, according to Santé.fr.

Santé.fr advises stopping tobacco, alcohol and cannabis as soon as you start trying, and if possible at least 3 months before conception. This applies to both partners. Do not hesitate to get help: a doctor, a midwife or Tabac Info Service (the French stop-smoking helpline) can support you through quitting.

Caffeine? According to Gaskins and Chavarro, the data on fertility are inconclusive. The pregnancy guidelines (no more than 200 mg of caffeine per day according to EFSA) are a good basis from the moment you start trying. See how much coffee per day.

For men: what matters for sperm

Male fertility is often forgotten. Yet the Salas-Huetos review points out that male factors, including reduced sperm quality, are involved in about 25% of infertility cases. The most consistent leads from the Salas-Huetos review: a diet rich in omega-3, antioxidants (vitamins E and C, beta-carotene, selenium, zinc, lycopene), folate and vitamin D, and low in saturated and trans fats, is associated with better sperm parameters. In men, high consumption of alcohol, caffeine, red meat and processed meat is associated with lower chances of pregnancy for their partner.

On supplements, Gaskins and Chavarro note that antioxidants seem beneficial when the man is supplemented, but that the studies do not tell us which ones, or at what dose. It is therefore better to focus on your plate, and to talk to your doctor before taking any supplement.

Food (Ciqual)	Zinc per 100 g	Selenium per 100 g
Pacific oyster, raw	21.8 mg	14.9 µg
Pumpkin seeds, dried	7.81 mg	not measured
Beef mince patty 5% fat, cooked	6.43 mg	not measured
Brazil nuts	4.06 mg	103 µg
Comté	3.84 mg	7.02 µg
Mussels, boiled	2.85 mg	55.7 µg
Sardines in oil, drained	1.89 mg	35 µg
Lentils, cooked	1.25 mg	not quantified

Brazil nuts are by far the richest in selenium: do not overdo them, as Anses sets a safe upper limit of 300 µg per day for adults. You will find more sources in our guides to foods high in zinc and foods high in selenium. Another practical detail noted by Santé.fr: sperm production needs the testicles to stay at around 35 °C, not 37 °C, so avoid prolonged sources of heat.

The baby-planning plate, in practice

There is no official « fertility diet ». The most solid approach is to follow the guidelines of the French National Nutrition and Health Programme (PNNS 2019), which overlap with those of the studies cited:

• At least 5 fruit and vegetables a day, for example 3 portions of vegetables and 2 fruits.
• Pulses at least twice a week (lentils, chickpeas, beans): fibre, plant protein, folate.
• A small handful of nuts a day, unsalted.
• At least one wholegrain starchy food a day: wholemeal bread, brown rice, wholewheat pasta.
• Fish twice a week, including one oily fish (sardine, mackerel, herring, salmon), varying the species.
• 2 dairy products a day.
• Poultry rather than red meat, limiting other meats to 500 g a week and processed meats to 150 g.
• Rapeseed, walnut and olive oils as a priority.
• Iodised salt, and fewer ultra-processed products and sugary drinks (no more than one glass a day).

These guidelines come close to the Mediterranean diet, the one that comes up most often in studies. For omega-3, our omega-3 guide details the sources; for iron, where the requirement rises to 16 mg per day with heavy periods against 11 mg otherwise (Anses), see iron and anaemia.

A typical day

• Breakfast: wholemeal bread, cheese, a kiwi.
• Lunch: spinach, egg and avocado salad, wholemeal bread, plain yoghurt.
• Afternoon snack: a handful of walnuts, an apple.
• Dinner: salmon, quinoa and spinach, vegetables, seasonal fruit.

For variety: lentil and spinach dahl, sardine and white bean salad, chickpea, spinach and tomato curry or grilled sardines with lemon.

Preparing for the pregnancy itself

The HAS recommends a preconception consultation, with a GP, a gynaecologist or a midwife. It is used to prescribe folic acid, but also to check toxoplasmosis and rubella immunity, bring vaccinations up to date (whooping cough, rubella, chickenpox if needed), review any long-term medication and talk about weight, tobacco and alcohol.

If pregnancy is planned in the short term, the HAS also calls for advice on listeriosis, and on toxoplasmosis if you are not immune, to be given from this point. You will find it in our guide to eating well during pregnancy and in the « pregnant » series, for example camembert when pregnant or sushi when pregnant. Also get into the habit of using iodised salt: iodine needs rise from 150 to 200 µg per day during pregnancy according to Anses.

Finally, no self-medication: the HAS reminds us that taking medicines without a prescription is discouraged as soon as a pregnancy is planned. This also applies to « fertility » supplements: Santé publique France (the French public health agency) points out that some contain vitamins which are contraindicated in high amounts during pregnancy.

Moving and sleeping

Santé.fr recommends physical and sporting activity of 30 to 45 minutes, 3 times a week, and tackling sedentary behaviour, including by walking. The PNNS aims for at least 30 minutes of dynamic activity a day. Santé.fr adds that sleeping at least 8 hours a night helps you stay healthy. To get started gently, see our guide to daily physical activity.

Common misconceptions

• « Pineapple, eggs or certain fruits boost fertility. » No. Inserm classes these « magic foods » as misinformation: no food has shown such an effect.
• « Vitamin B9 helps you get pregnant. » That is not its role. It protects the embryo against neural tube defects, which is why it is worth starting beforehand.
• « Soya and dairy products harm fertility. » According to Gaskins and Chavarro, neither dairy products nor soya have been consistently linked to lower fertility. During pregnancy and breastfeeding, however, Santé publique France recommends as a precaution not eating soya.
• « Vitamin D increases your chances. » The same review concludes that, in the absence of a deficiency, vitamin D does not seem to play an important role in human fertility.
• « Fertility is the woman’s business. » Wrong: tobacco, alcohol, cannabis and overweight also affect men.

When to see a doctor

Santé.fr advises seeing a doctor if you have not conceived after 12 months of regular intercourse without contraception, reduced to 6 months if you are over 35. Santé.fr also reminds us that fertility declines with age and advises, where possible, having children before 35 for a woman and before 44 for a man.

Frequently asked questions

How long before conception should you change your diet?

There is no official timeframe for diet. For folic acid, you need to start at least 4 weeks before conception according to the HAS. For tobacco, alcohol and cannabis, Santé.fr advises at least 3 months beforehand if possible, for both partners.

Should men take folic acid too?

No, the HAS recommendation applies to the future mother. Men are better off following the PNNS guidelines, stopping smoking, limiting alcohol and aiming for a healthy weight.

Is there a diet that supports fertility?

No diet has been shown to prevent infertility, Inserm points out. The Mediterranean diet is associated with better outcomes in observational studies, but without proof of cause and effect.

Do you need « fertility » supplements?

Apart from the folic acid prescribed to the future mother, not without medical advice. In men, antioxidants seem useful in some studies, without it being known which ones or at what dose.

Does coffee reduce your chances of pregnancy?

The data are inconclusive. Staying under 200 mg of caffeine a day, the EFSA guideline for pregnancy, is a simple precaution from the moment you start trying.

This article is for information only and does not replace the advice of your doctor, midwife or dietitian.

Our sources

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• Haute Autorité de santé, Commission de la transparence. Avis Acide folique CCD 0,4 mg. 18 décembre 2002.
• Inserm, Canal Détox. Des aliments « magiques » contre l’infertilité, vraiment ? 5 février 2025.
• Santé.fr. Impact du mode de vie : ce qu’il faut savoir pour préserver sa fertilité (mise à jour janvier 2026) ; Quels sont les facteurs influençant la fertilité féminine et masculine ?
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• Karayiannis D, Kontogianni MD, Mendorou C, et al. Adherence to the Mediterranean diet and IVF success rate among non-obese women attempting fertility. Hum Reprod. 2018;33(3):494-502. PMID 29390148.
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• Fan D, Liu L, Xia Q, et al. Female alcohol consumption and fecundability: a systematic review and dose-response meta-analysis. Sci Rep. 2017;7(1):13815. PMID 29062133.
• Sermondade N, Faure C, Fezeu L, et al. BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis. Hum Reprod Update. 2013;19(3):221-231. PMID 23242914.
• Inserm, Santé publique France, DREES. Enquête nationale périnatale, résultats de l’édition 2021. 2022.
• Anses. Table de composition nutritionnelle des aliments Ciqual 2025.