What the research behind the fertility diet actually found, the nutrient recommendation that matters more than the diet, and the half of the equation this page used to leave out.
The phrase “fertility diet” comes from a specific study, and the study is better than most of what gets written about it. It is also narrower than most of what gets written about it.
This page has been substantially rewritten. It previously addressed only women, described animal studies as though they were human evidence, and recommended low-fat dairy, which is the opposite of what the fertility diet score rewards.
Key Takeaways
- The original study found a 66% lower risk of ovulatory disorder infertility, not infertility overall (1).
- Folic acid, 400 to 800 mcg daily, is the strongest recommendation here (2).
- Male factors are just as likely as female ones (3).
- In one cohort, caffeine was linked to lower fecundability in men, not women (6).
- See a doctor after 12 months of trying, or 6 months if over 35 (4).
Where the Term Comes From
SaveA cohort of 17,544 women with no history of infertility was followed for eight years while they tried to conceive. Researchers built a dietary score from factors previously linked to lower ovulatory disorder infertility, and compared the highest and lowest fifths of adherence (1).
| What the score rewarded | Note |
|---|---|
| Monounsaturated fat rather than trans fat | The clearest single dietary signal in the study |
| Vegetable rather than animal protein sources | Swapping some meat for beans and lentils |
| Low-glycemic carbohydrates | Whole grains over refined flour and sugar |
| High-fat dairy rather than low-fat | This runs against ordinary advice, and against what this page used to say |
| Multivitamins | Largely the folic acid in them |
| Iron from plants and supplements | Rather than from meat |
The result: women in the highest quintile had a relative risk of 0.34 for ovulatory disorder infertility compared with the lowest, a 66% lower risk. Combining five or more low-risk lifestyle factors, including diet, weight control and physical activity, was associated with a 69% lower risk. The authors concluded that the majority of infertility cases caused by ovulation disorders may be preventable through diet and lifestyle (1).
That is a genuinely strong finding, and reading it accurately matters in both directions. It is an observational cohort, not a trial. And the outcome is ovulatory disorder infertility specifically. Blocked tubes, endometriosis, sperm problems and unexplained infertility are not what was measured.
The dairy correction
One item on that list is worth pulling out, because this page previously advised the opposite.
The fertility diet score rewarded high-fat dairy rather than low-fat (1). We are not telling you to switch on the strength of one cohort study, and full-fat dairy carries saturated fat that matters for your heart. But recommending low-fat dairy in an article named after a study that scored the reverse was an error, and it has been removed.
The Part That Is Not Really About Fertility
If you take one thing from this page, take this one, because it has the strongest evidence and the largest consequence.
The US Preventive Services Task Force recommends that all persons who are planning to or could become pregnant take a daily supplement containing 400 to 800 micrograms of folic acid. It is an A recommendation, with high certainty of substantial net benefit, and its purpose is preventing neural tube defects, of which around 3,000 pregnancies are affected each year in the US (2).
The timing is the point. Neural tube defects happen in the earliest weeks, often before a pregnancy is recognised, so the supplement has to be in place beforehand. This is not a fertility measure. It is the single best-supported nutrition action available to anyone who might become pregnant.
The Half This Page Used to Ignore
NICHD puts it plainly: problems in the male are just as likely as problems in the female, and it is equally likely that the cause is a combination from both partners (3). In couples affected by infertility, male factors account for roughly a quarter of cases (5).
An article about eating for fertility that addresses only one partner is not just incomplete, it steers couples towards a year of one-sided effort.
A systematic review of 35 observational studies found that diets rich in omega-3 fats, antioxidants including vitamin E, vitamin C, beta-carotene, selenium, zinc and lycopene, vitamin D and folate, and low in saturated and trans fats, were inversely associated with poor semen quality. Fish, shellfish, poultry, cereals, vegetables, fruit and low-fat dairy were positively associated with several sperm quality measures (5).
These are observational associations in a field where randomised evidence is scarce, and the review’s authors excluded the low-quality trials for that reason. The practical upshot is unglamorous: the same eating pattern, applied to both people.
Caffeine and Alcohol, With the Actual Findings
SaveBoth of these were vague on the previous version of this page. The specifics are more useful, and in one case they point the other way.
Caffeine. In a North American preconception cohort of 2,135 pregnancy planners, total caffeine intake of 300 mg a day or more was associated with reduced fecundability in men (fecundability ratio 0.72), but not in women. Caffeinated soda and energy drinks in men, and caffeinated tea in women, showed small reductions. The authors note the association in men was not monotonic (6).
Alcohol, before pregnancy. Pooled data from Danish and North American preconception cohorts covering 2,679 couples found little evidence that male alcohol consumption reduced fecundability (7). We are reporting that because it is what the study found, not because it is an endorsement.
Alcohol, once pregnant. This is a different question with a firmer answer. Alcohol during pregnancy can cause fetal alcohol spectrum disorders, which are lifelong and preventable, and there is no known safe amount or safe time (9). Since conception is usually recognised weeks after it happens, that reasoning applies to the trying period too.
If Cycles Are the Problem
The fertility diet study was about ovulation, so it is worth naming the most common reason ovulation goes wrong. Polycystic ovary syndrome affects how the ovaries work and is one of the most common causes of infertility in women; it is closely linked to insulin resistance, and weight and activity are part of its management (8).
That link is why the low-glycemic-carbohydrate element of the fertility score is not arbitrary. Our insulin resistance guide covers that side in detail, and the balanced diet guide covers the general pattern both partners can share.
Weight matters in both directions, and NICHD lists lifestyle and environmental factors among the causes of infertility for both sexes (3). Being significantly underweight can stop ovulation just as excess weight can disrupt it.
Do Not Let Diet Replace Assessment
This is the most important practical point on the page.
Infertility is defined as not achieving pregnancy after one year of regular unprotected sex, or after six months if the woman is older than 35 (4). If you are at that mark, the next step is an assessment for both partners, not another dietary adjustment.
Food can improve some of the conditions that support conception. It does not open a blocked tube, and it does not substitute for a semen analysis. Our fibre guide and walnut guide cover pieces of the eating pattern, but the calendar is the thing to watch.
Frequently Asked Questions
Does a fertility diet actually work?
There is one substantial study behind the term. In 17,544 women followed for eight years, the highest adherence to a defined dietary pattern was associated with a 66% lower risk of ovulatory disorder infertility compared with the lowest. Note the specific outcome: infertility caused by ovulation problems, which is one cause among many, not infertility in general.
What is the one supplement I should take?
Folic acid. The US Preventive Services Task Force recommends that all persons planning to or who could become pregnant take a daily supplement containing 400 to 800 micrograms, to prevent neural tube defects. That is an A recommendation with high certainty of substantial benefit, and it is much better established than anything else on this page.
Should my partner change anything?
Yes, and this page used to ignore that entirely. NICHD states that problems in the male are just as likely as problems in the female, and that a combination from both partners is equally likely. Male factors account for roughly a quarter of cases in couples with infertility.
Do I need to give up coffee?
The evidence is thinner and more surprising than usual. In a preconception cohort of 2,135 couples, total caffeine intake was associated with lower fecundability in men at 300 mg a day or more, but not in women. If someone in the couple should watch their caffeine, the data points at him.
When should we see a doctor?
After 12 months of regular unprotected sex without a pregnancy, or after 6 months if the woman is older than 35. Do not spend a year adjusting your diet instead of getting assessed.
The Bottom Line
The fertility diet is a real, measured pattern: more monounsaturated fat and less trans fat, more vegetable protein, low-glycemic carbohydrates, iron from plants and a multivitamin, and, contrary to what this page once said, full-fat rather than low-fat dairy. Highest adherence was associated with 66% lower risk of ovulatory disorder infertility, which is one cause of infertility among several. The better-evidenced action is simpler: 400 to 800 micrograms of folic acid daily, starting before conception. Apply the eating pattern to both partners, because male factors are just as likely as female ones, and get assessed after twelve months of trying, or six if you are over 35.
This article is for informational purposes only and is not a substitute for professional medical advice. Talk to a doctor or fertility specialist about your own situation, and see one after twelve months of trying, or six months if you are over 35, rather than continuing to adjust your diet alone.
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