Food and Fertility: The Basics

What can I eat to help support my fertility? Should I eat low carb? High fat? I get asked these questions A LOT. Let me break it down for you with the best research we have available. Depending on your fertility diagnosis, these recommendations might be modified for you, but this is a really good starting off point for anyone looking to conceive or even if you are deeper into your fertility journey and want to make sure your diet is working well for you.

Let’s start with the basics – macronutrients. All food contains carbohydrates, protein and/or fats. I think it makes sense to start here before we get into specific foods and their impact, because this is probably much more important for you. We will discuss specific foods in another post.

CARBOHYDRATES

One of the most important factors when it comes to your diet is trying to maintain stable blood sugar levels. We do this by including protein, fibre and healthy fats at all meals (not just dinner!), and minimizing intake of highly refined carbohydrates.

Highly refined carbs mean white breads, white rice, pastries, candies etc. These can be problematic when it comes to your fertility because they cause a rapid increase in your blood sugar levels, which causes your pancreas to release the hormone insulin to clear sugar out of your bloodstream and get it to your cells. If this process happens regularly, your body stops listening to insulin, so your pancreas has to release more insulin to do the same job, and blood sugar levels remain elevated.

One of the ways to measure your longer term blood sugar control is by a blood test called HbA1c. Having a higher HbA1c level means your blood sugar has generally been higher over the last 3 months. In one study, women who had a higher HbA1c level were half as likely to get pregnant during a 6 month period[1].  Thankfully, it’s not the amount of carbs that seem to be an issue, but more so the type of carbohydrates. Women who consumed higher amounts of cold breakfast cereals, white rice and potatoes were 78% more likely to have ovulatory infertility, whereas brown rice and dark breads were linked to a lower risk of infertility.

It is thought that elevated insulin impairs ovulation by creating hormonal imbalance in the ovaries[2]. This is one of the main reasons why women with PCOS (who often have impaired glucose metabolism) can have irregular ovulation and periods. But, a study revealed that elevated insulin and blood sugar can also decrease egg quality and this effect was seen in all women experiencing infertility, not just women with PCOS[3].

Elevated blood sugar and insulin also negatively affect mitochondria. In an animal study, researchers have found that diabetic mice have more chromosomal abnormalities in their eggs which can impact embryo development and implantation, and increase the risk for miscarriage.

Choose complex carbohydrates from vegetables, legumes, nuts, seeds, and whole grains like quinoa, wild rice, brown rice, steelcut oats or buckwheat. I have found that lentil, bean or chickpeas pastas are a great alternative to regular pasta and much better for your blood sugar control. Corn and white potatoes do quickly increase blood sugar, so try to opt for a variety of other vegetables instead.

PROTEIN

Protein is often overlooked, but so important for overall health and embryo development. IVF patients who switched to a lower carbohydrate and higher protein diet for only 2 months and then underwent another cycle increased their blastocyst formation rate from 19% to 45% and their clinical pregnancy rate from 17% to 83%. The diet aimed for 27% of your calories from protein, 40% of your calories from carbs and the rest (33%) from fat[4]. This percentage is very achievable and is really not considered a “high protein” or “low carb” diet by our current standards. Moderation works!

You can get your protein from a variety of sources – fish, eggs, poultry meat, lentils, legumes or beans. If you are a big meat eater, replacing 5% of animal protein in your diet with vegetarian protein reduced ovulatory infertility by 50%[5]. Fish is especially beneficial (for both men and women) and a higher seafood intake in the diet (2 meals/week) is associated with a shorter time to pregnancy[6], and better quality embryos in IVF[7]. Use the seafood selector to choose the healthiest seafood options.

FATS

Fats can be classified into 3 major categories – unsaturated (polyunsaturated and monounsaturated), saturated and trans fats. Unsaturated fats are generally from vegetable sources and are liquid at room temperature while saturated fats are predominantly from animal sources and are solid at room temperature. Trans fats are generally created in either the cooking or processing of food.

Diets high in unsaturated fats such as those found in fish, nuts, seeds and olive oil have been shown to be beneficial for fertility, while diets higher in saturated fats and red meat have been shown to impair fertility and egg quality[8]. This might be due in part to the impact of endocrine disrupting chemicals found in red meat.

Trans fats should be minimized as much as possible. Trans fats are found in processed foods such as crackers, baked goods, margarine and some fried foods. Every 2% increase of trans fats in the diet (instead of monounsaturated fats) doubles the risk of ovulatory infertility[9].

TAKE-HOME POINTS

The diet that has been shown to have the greatest impact on fertility is the Mediterranean Diet. This follows along with all of the dietary aspects mentioned above - lean protein, lots of healthy fats, and a variety of colourful produce with some select whole grains.

Fertility can be stressful, and you definitely don’t have to be “perfect” every meal, but try to incorporate these dietary principles consistently to see the most benefit.

[1] Hjollund et al., “Is Glycosylated Haemoglobin a Marker of Fertility?”

[2] Sakumoto et al., “Insulin Resistance/Hyperinsulinemia and Reproductive Disorders in Infertile Women.”

[3] Jinno et al., “Advanced Glycation End-Products Accumulation Compromises Embryonic Development and Achievement of Pregnancy by Assisted Reproductive Technology.”

[4] Russell et al., “Does Changing a Patient’s Dietary Consumption of Proteins and Carbohydrates Impact Blastocyst Development and Clinical Pregnancy Rates from One Cycle to the Next?”

[5] Chavarro et al., “Protein Intake and Ovulatory Infertility.”

[6] Gaskins et al., “Seafood Intake, Sexual Activity, and Time to Pregnancy.”

[7] Chiu et al., “Serum Omega-3 Fatty Acids and Treatment Outcomes among Women Undergoing Assisted Reproduction.”

[8] Braga et al., “The Impact of Food Intake and Social Habits on Embryo Quality and the Likelihood of Blastocyst Formation.”

[9] Chavarro et al., “Dietary Fatty Acid Intakes and the Risk of Ovulatory Infertility.”