Nutrition when trying to conceive influences fertility primarily through a few well-supported factors: a balanced nutrient status (especially folic acid, iodine, and iron), body weight in the normal range, and avoiding high amounts of alcohol, caffeine, and trans fats. The only figure that all German professional authorities agree on is the 400 µg folic acid recommendation by the Federal Institute for Risk Assessment (BfR) prior to pregnancy. For almost all other nutrition-related questions when trying to conceive, the evidence base is thinner and observational rather than conclusive compared to what many online guides suggest. This article contextualizes what is actually supported by studies from the American Society for Reproductive Medicine (ASRM) and the Harvard research group led by Jorge Chavarro, what remains unclear, and which nutrient figures from other providers simply do not align with the reference values of the DGE and BfR.

How much does nutrition really influence fertility?

Nutrition demonstrably influences fertility, but to a significantly more limited extent than many guides suggest: the correlation is best documented in women with cycle irregularities, not in women with normal ovulation. In its current position statement, the American Society for Reproductive Medicine (ASRM) notes that there is "little evidence that dietary variations improve fertility in women without ovulation disorders."

→ Source: American Society for Reproductive Medicine (ASRM), Practice Committee, "Optimizing natural fertility: a committee opinion", Fertility and Sterility, 2022

The most important exception concerns this exact group: In the well-known Nurses' Health Study II at the Harvard T.H. Chan School of Public Health, reproductive epidemiologists Jorge Chavarro and Walter Willett investigated how a "Fertility Diet Score" composed of several dietary factors (more monounsaturated fats instead of trans fats, more vegetable protein, whole-milk products instead of low-fat milk, lower glycemic index, a multivitamin supplement) correlates with ovulatory infertility. In the study, women with the highest score on this scale had a significantly lower relative risk of ovulatory infertility than women with the lowest score.

→ Source: Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. "Diet and Lifestyle in the Prevention of Ovulatory Disorder Infertility." Summary: Harvard Gazette, Changes in diet and lifestyle may help prevent infertility, 2007

Important for context: The ASRM explicitly points out that this exact "Fertility Diet Score" showed no demonstrable additional benefit in studies on assisted reproduction (ART cycles). The effect thus appears to be specific to the natural restoration of a regular ovulation cycle, rather than generally for "better chances" in any form of trying to conceive. This clearly distinguishes nutrition from medical treatment: it can make a real difference in the case of cycle irregularities, but it does not replace diagnostics or fertility treatment.

→ Source: ASRM Practice Committee, "Optimizing natural fertility: a committee opinion", 2022

Overview of the most important nutrients

When trying to conceive, five nutrients are particularly relevant for which there are clear, official reference values: folate/folic acid, iodine, iron, omega-3 fatty acids (specifically DHA), and zinc. The German Nutrition Society (DGE) and the BfR have published their own coordinated figures for most of these, which differ clearly from the sometimes contradictory information on international guide sites. The reference values for folate, iodine, iron, and zinc are so-called D-A-CH reference values, jointly derived by the DGE, the Austrian Nutrition Society (ÖGE), and the Swiss Nutrition Society (SGE), and thus apply largely equally to Germany, Austria, and Switzerland.

→ Source: German Nutrition Society (DGE), Reference values for nutrient intake

Sources: DGE reference values for folate, iodine, iron, zinc; BfR recommendation on folic acid when planning pregnancy; Gesund ins Leben (Healthy Start network) on DHA during pregnancy.

For folic acid, the figure 800 µg often circulates online instead of the 400 µg that applies in Germany. The reason is likely due to different national baseline values and conversion conventions for folate equivalents, which are handled inconsistently internationally. For the German-speaking region, the figure of 400 µg of synthetic folic acid daily as a separate supplement remains the standard, as expressly recommended by the BfR and used by our own fact-checked folic acid guide, starting at least four weeks before conception.

→ Source: German Federal Institute for Risk Assessment (BfR), Getting pregnant? But not without folic acid!

As of 2025, a lower DGE reference value of 150 µg for adults and 220 µg for pregnant women applies for iodine because the DGE has revised its calculation methodology, not because the actual requirement has changed. Details on symptoms of a deficiency, current warnings regarding overdosed iodine supplements, and proper context can be found in the comprehensive iodine deficiency guide. Regarding iron: A deficiency can only be reliably determined via a ferritin blood test, not by symptoms such as fatigue alone; more on this in the iron guide for women.

For omega-3, the German "Gesund ins Leben" network, which advises professionals on nutrition before and during pregnancy, recommends at least 200 mg of DHA per day. Anyone who regularly eats fatty sea fish once or twice a week usually meets this value through their diet; for those who do not, "Gesund ins Leben" recommends a targeted DHA supplement, such as one based on fish oil or algae.

→ Source: Gesund ins Leben network, Are supplements with omega-3 fatty acids necessary during pregnancy?

What is better to avoid when planning a pregnancy

Regarding alcohol and caffeine, the ASRM provides specific threshold values, not a blanket "zero-tolerance" principle. In the cited studies, more than two alcoholic drinks per day were associated with a significantly increased risk of infertility, while less than one drink per day was even associated with a lower risk in one study; the data is inconsistent overall. For caffeine, very high consumption of about 500 mg per day (more than five cups of coffee) showed an increased risk, while moderate consumption of one to two cups daily showed no discernible negative effects.

→ Source: ASRM Practice Committee, "Optimizing natural fertility: a committee opinion", 2022

Trans fats are classified as negative for fertility in the same ASRM opinion, which is why the "Fertility Diet" by Chavarro and Willett expressly recommends monounsaturated fats instead of trans fats. Trans fats are primarily found in highly processed baked goods, fried foods, and some convenience products; in Germany, their share in food has been legally limited since an EU regulation in 2021 anyway.

→ Source: ASRM Practice Committee, "Optimizing natural fertility: a committee opinion", 2022

Regarding fish high in mercury (such as large amounts of tuna, swordfish, shark), the Federal Institute for Risk Assessment advises pregnant women and those planning a pregnancy to limit their consumption, because methylmercury can impair child nerve development, while fatty, lower-mercury sea fish like salmon or herring remain expressly recommended as an omega-3 source.

→ Source: German Federal Institute for Risk Assessment (BfR), Iodine, Folate/Folic Acid and Pregnancy

Does this also apply to men?

Yes, but the body of evidence regarding male fertility is overall weaker and less nutrition-specific than for women. According to the ASRM, regular cannabis use in men shows an approximately 29 percent lower sperm count compared to non-users, while "no effect on semen parameters" could be proven for caffeine. Chronically high alcohol consumption, on the other hand, is associated with lower sperm count and motility.

→ Source: ASRM Practice Committee, "Optimizing natural fertility: a committee opinion", 2022

Regarding heavily advertised antioxidant supplements (such as those with zinc, selenium, vitamin C, and E) for men with reduced fertility, a current Cochrane review presents a significantly more cautious picture than marketing texts often suggest: The authors found only evidence of "very low certainty" for a possible improvement in the live birth rate, which disappeared as soon as studies with a high risk of bias were removed from the analysis. Zinc is not specifically highlighted in the review as an effective individual substance.

→ Source: de Ligny W et al., "Antioxidants for male subfertility", Cochrane Database of Systematic Reviews, 2022

In practical terms, this means: Regarding male fertility, general lifestyle factors (no cannabis use, moderate alcohol consumption, non-smoking, normal weight) are currently better supported than the benefit of individual nutritional supplements. Couples who have been unsuccessfully trying to conceive for a long time should consider a urological-andrological assessment for the man as equal in importance to the gynecological assessment for the woman, rather than focusing solely on diet.

Weight and fertility

Both significant underweight and obesity are associated with reduced fertility according to the ASRM, though the statement expressly does not name an "ideal" target weight for every individual woman. In both extremes, the mechanism works, among other things, via disrupted hormone regulation, which can make ovulation irregular or cause it to stop entirely.

→ Source: ASRM Practice Committee, "Optimizing natural fertility: a committee opinion", 2022

Important for context: Weight is a statistical risk factor at the population level, not an individual diagnosis, and certainly not a reason for shame or self-reproach. Many women who are underweight or overweight get pregnant without problems; many women with a normal weight still have cycle disorders. If you are unsure whether your weight is affecting your fertility, the most reliable assessment is obtained in a gynecological practice, not via general BMI charts on the internet.

Is a healthy diet alone enough, or are supplements needed?

For most nutrients, a balanced diet with enough vegetables, whole grains, fish, legumes, and iodized table salt is largely sufficient. An exception is folic acid for targeted neural tube defect prevention: Here, the BfR and DGE expressly recommend a separate 400 µg supplement, regardless of other dietary status, because the specific requirement during early embryonic development is often difficult to meet reliably through food alone in practice.

→ Source: Veyt Folic Acid Guide, with BfR and DGE sources

The Consumer Association of Baden-Württemberg (Verbraucherzentrale) expressly warns in its market analysis of fertility and pregnancy supplements against assuming that "more" is generally "better": According to the analysis, many combination products available on the market contain significantly more ingredients (and a correspondingly higher price) than is actually necessary for most women. Instead of taking everything at once according to the so-called "shotgun approach," the Consumer Association recommends determining your own needs in a targeted manner, for example, in consultation with a doctor or a nutrition expert.

→ Source: Consumer Association of Baden-Württemberg, Nutritional supplements for pregnancy and when planning a family

For omega-3: Anyone who does not regularly eat fatty sea fish can, according to "Gesund ins Leben," benefit from a targeted DHA supplement to reach the recommended minimum of 200 mg daily. According to the product label, the Premium Omega-3 Complex from Veyt provides 2000 mg of omega-3 fatty acids (DHA & EPA) per serving, thus offering plenty of room above the recommended minimum even with low fish consumption.

For iron, an important restriction applies: Unlike with folic acid, no one should supplement here as a precaution without having proven a deficiency. A ferritin blood test reliably shows whether a deficit exists at all, because unnecessary iron intake without a deficiency is associated with side effects and potential risks according to the BfR. Only once a deficiency is confirmed is a supplement like Iron Vitality Core with 25 mg of iron bisglycinate per tablet a sensible, well-tolerated option for targeted correction.

→ Source: German Federal Institute for Risk Assessment (BfR), Maximum quantity proposals for iron

Schedule: The three months before planning a pregnancy

A practical timeline helps to ensure that the most important, evidence-based measures are not just addressed at the last minute. It does not replace individual consultation but is based on the sources from the BfR, DGE, and ASRM mentioned in this article.

• From now on (at least 4 weeks before intended conception): Start with 400 µg of folic acid daily as a supplement, regardless of how long it is expected to take until pregnancy.
• In the coming weeks: Check iodine and iron intake via diet (iodized salt, sea fish, dairy products, iron-rich foods combined with vitamin C); if unsure, arrange a blood test (ferritin, possibly iodine excretion) rather than supplementing on suspicion.
• Parallel: Reduce alcohol consumption to a maximum of one drink per day, limit caffeine to one to two cups of coffee, quit smoking and cannabis completely if possible; this applies to both partners.
• Until pregnancy and beyond: Continue folic acid until the end of the first trimester; have all other nutrients managed by a doctor as part of regular pregnancy care.
• If pregnancy does not occur after 12 months (or 6 months if 35 or older): seek gynecological or reproductive medical clarification for both partners, regardless of diet.

→ Source: ASRM Practice Committee, "Definition of infertility: a committee opinion", 2023

Limits of this guide

The majority of research on nutrition and fertility is observational (epidemiological), not experimental: studies like the Nurses' Health Study II show correlations between dietary patterns and infertility risk, but they do not prove causality in the strict sense of controlled trials. Women who generally eat healthier often differ from those who do not in other, hard-to-measure factors (exercise, smoking, socioeconomic status), which complicates interpretation.

The Cochrane review on antioxidants in men also makes this problem explicit: an initially positive effect disappeared as soon as methodologically weaker studies were removed from the analysis, a classic sign of bias due to study quality rather than a genuine biological effect. This article does not replace individual diagnostics, nutritional counseling, or fertility treatment.

Expert Perspectives & Protocol Breakdown

Note on source selection: The expert roster used for other Veyt articles (covering topics such as keto, TCM, or biological medicine) contains no truly relevant specialists for the topic of nutrition for fertility. Instead of artificially inserting someone without a background in reproductive medicine, this section relies on the two institutional and scientific voices that are truly relevant to this topic.

ASRM Practice Committee (American Society for Reproductive Medicine)

What the committee recommends: In its "Optimizing natural fertility" statement, the ASRM systematically evaluates existing evidence on nutrition, weight, alcohol, caffeine, and substance use, explicitly ranking it based on the level of evidence rather than issuing blanket recommendations. Their approach is population-based and conservative: they identify where the evidence supports a correlation (such as dietary patterns in ovulatory disorders, extreme weight, and high alcohol and caffeine consumption) and just as clearly state where it is lacking (such as for most individual nutrients for women without cycle disorders).

Jorge Chavarro & Walter Willett (Harvard T.H. Chan School of Public Health)

What their research shows: With the Nurses' Health Study II, Chavarro and Willett have presented the most influential work to date on the relationship between a specific dietary pattern ("Fertility Diet Score") and ovulatory infertility. Their focus is on a very specific subgroup—women with ovulatory disorders—not fertility in general, and their results are epidemiological, not derived from randomized trials.

Where They Differ

Not a true contradiction, but a difference in the scope of the claims: the ASRM draws a more cautious conclusion from the Chavarro/Willett research than many popular guidebooks, explicitly limiting the benefits to women with ovulatory disorders and stating that there is no confirmed added benefit for ART (assisted reproductive technology) cycles. Chavarro and Willett's own publications frame the results more optimistically for their studied cohort, a nuance that is frequently omitted in secondary reporting.

What the Evidence Says

Taken together, a clear picture emerges: nutrition can make a demonstrable difference for women with ovulatory disorders, but it is not a reliable "fertility lever" for women with a normal cycle. However, for all women, regardless of cycle status, there is well-supported evidence for the BfR's 400 µg folic acid recommendation, adequate iodine and iron intake, and the avoidance of high amounts of alcohol, caffeine, and trans fats.

Frequently Asked Questions

What should I eat when trying to conceive?

A balanced diet with vegetables, whole grains, legumes, lean meat or fish, and iodized table salt covers most nutrients. In addition, the BfR recommends that all women trying to conceive take 400 µg of synthetic folic acid daily as a separate supplement.

Which nutrients are most important when trying to conceive?

The best-supported are folic acid (400 µg daily as a supplement), sufficient iodine intake (150 µg, or 220 µg during pregnancy), and sufficient iron intake (16 mg, or 27 mg during pregnancy, if a deficiency is confirmed). Omega-3 (DHA) and zinc play a supplementary role.

Do I have to take nutritional supplements when trying to conceive?

Not all of them, but folic acid is the exception: here, the BfR and DGE recommend a separate 400 µg supplement regardless of one's general nutritional status. For iodine, iron, and omega-3, requirements depend on one's individual diet; the consumer advice center explicitly advises against taking every marketed combination supplement by default.

Does nutrition also affect male fertility?

Yes, although the body of evidence is weaker than for women. Lifestyle factors such as avoiding cannabis (associated with roughly 29 percent lower sperm count with regular use) and moderate alcohol consumption are best supported; for antioxidant supplements, a Cochrane review found only very uncertain evidence.

When should I start changing my diet?

Folic acid supplementation should begin at least four weeks before planned conception, as the embryo's neural tube closes by the end of the fourth week of pregnancy. Other dietary adjustments (alcohol, caffeine, nutrient intake) can be sensibly addressed step-by-step several months in advance.

How much alcohol and caffeine are still considered safe when trying to conceive?

According to the ASRM, consuming more than one alcoholic beverage per day or more than two drinks per day showed an increased risk of infertility, while one to two cups of coffee daily had no discernible negative effects. There are no definitive universal limits for every woman; when in doubt, the safer choice is less.

When should I see a doctor about infertility?

According to the ASRM, after 12 months of regular, unprotected intercourse without pregnancy if the woman is under 35, or after 6 months if she is 35 or older. This applies regardless of how carefully the diet has already been adjusted.

References & Scientific Citations

• American Society for Reproductive Medicine, Practice Committee (2022). Optimizing natural fertility: a committee opinion, Fertility and Sterility.
• American Society for Reproductive Medicine, Practice Committee (2023). Definition of infertility: a committee opinion.
• Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC (2007). Diet and Lifestyle in the Prevention of Ovulatory Disorder Infertility, Obstetrics & Gynecology. Summary: Harvard Gazette (2007).
• de Ligny W, Smits RM, Mackenzie-Proctor R, et al. (2022). Antioxidants for male subfertility, Cochrane Database of Systematic Reviews.
• German Federal Institute for Risk Assessment (BfR). Getting pregnant? But not without folic acid!
• German Federal Institute for Risk Assessment (BfR). Iodine, Folate/Folic acid and pregnancy.
• German Federal Institute for Risk Assessment (BfR). Maximum level proposals for iron in food including nutritional supplements.
• German Nutrition Society (DGE). Reference values for nutrient intake (Folate, Iodine, Iron, Zinc).
• Network "Gesund ins Leben". Are omega-3 fatty acid supplements necessary during pregnancy?
• Consumer Advice Center Baden-Württemberg. Nutritional supplements for pregnancy and trying to conceive.

This article serves as general information and does not replace medical advice, diagnosis, fertility treatment, or individual nutritional counseling. In the case of difficulty conceiving, existing medical conditions, or before starting any nutritional supplements, please consult a gynecologist, urologist/andrologist, or fertility center.