It’s easy to overgeneralize the role carbohydrate consumption can have on fertility and so here we need to be careful and refine how we categorize carbohydrates.
As you can see below in the Nurses Health Study, women who consumed carbohydrates with the highest glycemic index (like white rice and potatoes) were far more likely to suffer from anovulatory infertility than women who consumed carbohydrates with a low glycemic index (like whole grains, vegetables, and beans). When possible, you almost always want to trade off high for low glycemic carbohydrates.
For women undergoing IVF, the data shows those who have higher whole grain consumption enjoy higher live birth rates after correcting for discrepancies in age, race, duration of infertility, and more. Below you can see the data from over 400 cycles performed at Harvard. While the study occurred in a single center, the gains made between the highest and lowest quartile are astonishing for their size and consistency.
At the moment, the data on how red meat and white meat impact fertility is mixed, but on balance it is negative, especially in the case of processed red meat.
When Harvard investigators in charge of the Nurses Health Study (which we covered above) focused on diet patterns for women in their 30’s with no previous fertility issues, they noticed women in the highest meat consumption category were 40% more likely to have ovulatory dysfunction (if a woman cannot ovulate she cannot conceive naturally). One additional daily serving of meat translated into a 32% higher risk. As you can see below, the opposite was true with vegetable consumption.
Unfortunately, the data we have on how meat intake impacts a woman’s ability to conceive through IVF is pretty paltry. The best study we have comes from a single center (which is less preferable) in Brazil, and if it’s even close to accurate it paints a dim picture of red meat’s correlation to poorer IVF outcomes. As you can see below, red meat’s inverse correlation with ability to make quality embryos, and conceive, looks to be on par with smoking.
For men, the better run studies seems to suggest consuming poultry is of little harm. On the other hand consuming processed red meats (like sausage or baloney) is more closely associated with issues than eating unprocessed red meats (like a piece of chicken or steak). If you’re trying to make the distinction, if you’re unable to trace a food back to a specific part of the animal, it’s likely processed and probably unhelpful.
Amongst women trying to conceive naturally, greater seafood intake correlates with better fertility. Below is a study of 500 couples tracking their Time To Pregnancy based on seafood and fish consumption. Women who consumed more than 8 servings of seafood and fish per menstrual cycle enjoyed 40 - 60% greater likelihood of conceiving compared to women who hardly consumed it all.
However, the greatest benefit was conferred when both members of a couple ate 8 or more servings per cycle. As you can see below, the cumulative odds of conception after each menstrual cycle is higher for the couples where both partners consume high levels of seafood and seafood rather than when just one partner does.
All the same, some of the benefit of consuming seafood can be diminished if that seafood has been exposed to pollutants or mercury. As a result, where the seafood is caught, and what type it is, matters.
A good illustration of this are two similar studies performed in Sweden (which has cleaner waters) and in the Lake Ontario region (more contaminated waters) that looked at local fish consumption and time to pregnancy. In Sweden, investigators saw an encouraging positive correlation between the two whereas in the Lake Ontario region investigators a 5 - 10% inverse correlation between local fish consumption and fertility.
Today the American College of Obstetricians and Gynecologists recommends that women who are trying to conceive eat two to three servings of fish per week but limit their fish composed of high levels of mercury. Items like canned tuna are of moderate risk and should only be eaten once per week.
Within an IVF population, the Brazilian study we referenced earlier noted that women who consumed greater levels of fish recorded higher levels of blastocyst embryos (embryos most likely to lead to a live birth), but that did not translate into a higher predicted rate of pregnancy.