Decoding The Fertility Diet, Part 3:
Protein and Fertility

“How much protein is enough?”

For many years, the nutritional world has focused primarily on this one question as it relates to the topic of protein. However, we are beginning to discover that protein QUALITY is just as important as protein quantity – a concept that’s especially true when addressing your reproductive health and overall wellness for that matter.

Other equally important questions to understand, include:

“Are all protein sources created equal?”

“What else accompanies the proteins that we eat?”

“Should we be eating less animal protein?”

The answers to these questions will help you master a commonly overlooked topic relating to nutrition and your fertility.

We know, we know… from a basic nutrition standpoint, protein isn’t all that sexy. But, stay with us as we promise it’s gonna get exciting once you understand a few foundational principles.

Most of us are quite familiar with protein when it comes time to eat – beef, chicken, and pork are protein favorites in the Standard American Diet. Yup, that means fish and beans trail way behind. And as you’ll come to discover momentarily, this might be doing your efforts of trying to conceive a big disservice.

Top Sources of Protein:

Once consumed, our bodies break down protein into molecules referred to as amino acids. As a built-in safety mechanism of sorts, our bodies can produce 13 of the 20 or so total amino acids — the remaining ones (the essential amino acids) must come from the foods that we eat.

While we’re on the topic of amino acids, you may also see proteins discussed as being complete versus incomplete proteins. This simply refers to whether a protein source contains all the essential amino acids (complete) or is lacking one or more of them (incomplete). As we discuss in the Fertility Foods Formula, this isn’t really that big of a deal as long as you’re eating a balanced diet consisting of multiple different protein sources.

Proteins act as the structural building blocks for nearly every tissue in our bodies – sperm and eggs included! They also support the function of every major cell in our bodies, from our red blood cells to our immune cells. Needless-to-say, proteins are kind of important. 

Of course, proteins also supply fuel for our body’s energy needs. And as you’re about to learn, both the quantity AND quality matters when it comes to fueling for fertility. 

Before diving into the topic of protein quality, let’s take a look at just how much protein you should be consuming.

To support your everyday hustle, you require about 7 grams of protein for every 20 pounds of body weight… that’s about 50 grams of protein a day for someone weighing 140 pounds. For quick reference, 50 grams of protein is equivalent to 1 large chicken breast.

Protein content of various foods

As you can see, protein need not make up a significant portion of our total caloric intake. In fact, for most individuals, protein intake should be between 10-35% of your total caloric intake. As a general rule, keep your protein intake around 3-4 servings per day (a typical serving equals the size of a deck of cards) and you’ll be supporting your efforts to conceive.

And because we know someone is going to ask… experts aren’t entirely sure about the safe upper limit of protein intake for the average healthy adult.

With that said, researchers from Harvard have discovered that women who eat more protein have a significantly higher risk of ovulatory infertility compared to those who eat less protein. To be more specific, those who ate an average of 115 grams of protein per day were 41% more likely to have reported ovulatory infertility compared to those who only ate 77 grams per day.

Bottom line: Get enough protein, but don’t overdo things with a high-protein diet.

Before we dive into the best protein sources for fertility, it’s important to note that few foods deliver just protein. Some protein-rich foods contain health-promoting nutrients like vitamins, minerals, antioxidants, and fiber, while other protein-rich foods contain potentially harmful components like cholesterol, saturated fats, and nitrites.

A few examples regarding protein sources and their additional constituents include:

In addition to the various nutritional components contained within a given protein, some protein sources contain environmental contaminants (e.g., pesticides, heavy metals, persistent organic pollutants, etc.), which have been shown to have a negative impact on reproductive health.

Being mindful of the other components in your frequently consumed protein sources can definitely enhance your health. So, consider this a friendly reminder to review the nutrition facts of the foods that you eat and source your protein wisely!

Upon careful examination of the scientific literature, some pretty interesting trends for sourcing your protein should be considered the next time you go to the grocery store.

First, let’s revisit the Nurses’ Health Study analyzed by a group of Harvard researchers that we mentioned above. In this study, increased consumption of ANIMAL PROTEIN – as well as a higher total protein intake – was associated with an increased risk of ovulatory infertility. In fact, adding one serving of meat per day was associated with a 32% increased risk for ovulatory infertility.

Upon closer review, the increased risk for ovulatory infertility was mostly attributed to red meat, turkey, and chicken. Interestingly, fish consumption wasn’t associated with ovulatory infertility, and plant proteins protected against it.

Speaking of plant proteins, the Harvard researchers also looked at the effect of eating vegetable protein instead of animal protein while keeping calories constant (i.e., making a simple switch). Low and behold, replacing 25 grams of animal protein with 25 grams of plant protein was associated with a 50% lower risk of ovulatory infertility.

Check out the infographic below to see what 25 grams of protein looks like… it’s a pretty easy substitution when it comes right down to it.

So, we’re beginning to see that plant-based proteins are beneficial for reproductive health, but what about fish… does FISH really not have that big of an impact?

Remember ovulation is only one aspect of reproductive health. In the LIFE study, couples who consumed an average of 2 servings of seafood per week in a given menstrual cycle had a 60% shorter time to pregnancy as well as a 13% lower incidence of infertility compared to couples who consumed one or fewer seafood servings during the same period. Yes, these findings remained significant even after controlling for intercourse frequency.

More recently, findings from the Environmental and Reproductive Health (EARTH study) showed that women who adhered to a “Pro-Fertility Diet” characterized by protein intake from seafood and soy (along with a few other healthy dietary habits) had a 43% higher chance of clinical pregnancy and a 53% higher chance of a live birth following IVF.

Similarly, another study among women undergoing IVF demonstrated that fish consumption had a positive impact on embryo formation at day 5, whereas red meat was associated with a reduced day 5 embryo formation.

Clearly, there’s something to be said about swapping out some of your conventional animal proteins like chicken, turkey, and red meat for other healthy sources of protein including fish and plants! 

If you are ready to increase your fish intake, start with those rich in omega-3 fatty acids (remember the importance of those good fats). Just be sure to minimize larger fish (e.g., tuna, swordfish, shark, and tilefish) that accumulate toxins like methylmercury that can harm reproductive health. 

Before we take a look at one of the more controversial plant-based proteins when it comes to your fertility, it’s important that we take a moment to review DAIRY once again. 

As we’ve mentioned elsewhere, diary is a bit of a mixed picture. Consuming low-fat dairy products instead of full-fat dairy products (e.g., whole milk) has been associated with a greater risk of ovulatory infertility. 

Many hypothesize this to be related to the androgenic hormones (e.g., testosterone) left behind after the skimming process. Estrogen and progesterone bind to fat molecules and are subsequently removed when producing low-fat dairy. 

So while dairy may be a potential source of protein (along with calcium and vitamin D too), be mindful of which type you consume. If you’re wondering whether you should consume dairy at all, make sure to read our post dedicated to this topic.

Lastly, a word on SOY… 

Although soy is a great plant-based protein, we know there’s a lot of debate about its consumption given the potential impact it may have on your hormones, estrogen in particular. Therefore, we thought it deserved a little section of its own. Don’t worry, we’ll cover the topic in greater detail in another post.

To summarize things, the evidence involving soy and fertility is limited and conflicting. 

Overall, prospective studies have found either a positive or a neutral correlation among reproductive outcomes when supplementing soy and phytoestrogens. 

As for the positive findings, soy consumption has been associated with increased pregnancy rates after both intrauterine insemination and in vitro fertilization as well as increased live birth rates in women having undergone assisted reproductive therapy. 

Soy isoflavones have also been shown to have a protective effect against the adverse impact of bisphenol A (BPA) exposure, especially among women being treated with assisted reproductive technologies (i.e., IVF).

To be clear, we’re not suggesting you should supplement with soy, but consuming real soy containing foods such as tempeh, tofu, or edamame in moderation won’t have a negative impact on your fertility, and may actually help… particularly if it’s taking place of processed meat on your plate!

Okay, still think protein isn’t that interesting when learning how to nourish your body for optimal reproductive health?

We didn’t think so 😏

Clearly, there’s more to the story than how much protein you should eat. However, there’s no reason to get confused with how to apply all the information you’ve just learned.

Our bottom-line, everyday approach to protein? Adopt a Mediterranean Diet for healthy eating.

Here’s our application of the Mediterranean Diet when trying to conceive: