Why Chicken Breast Isn’t the Best Protein for Women and Hormone Health

When it comes to considering the best sources of protein for women, we are often made to believe that the leaner the better. Chicken breast, egg whites, and grilled white fish are often front and center as the “healthy” options. However, these proteins are lacking key nutrients that are essential for supporting hormone health. This is especially important for women dealing with hormone issues like irregular periods, fertility struggles, or thyroid issues. Let’s explore why types of protein matter, primarily the difference between glycine-rich proteins and muscle meats.

Amino Acids: What Are They and How Do They Influence Protein Quality?

Amino acids are the building blocks of protein, which is essential for every single cell in our bodies. Proteins serve as the raw materials for hormones, immune molecules, brain signaling compounds (neurotransmitters), enzymes, and more. Every process in our body relies on proteins, and therefore amino acids.

Some amino acids are “essential,” meaning we must get them from food, while others are considered “non-essential.” Our bodies can make non-essential amino acids, unless the demand for them exceeds our own production or supply, in which case they become “conditionally essential.” 

Not all protein sources are created equal, and it comes down to their amino acid composition. Complete proteins, like most animal-based proteins as well as soy, contain all of the essential amino acids. Incomplete proteins, like more plant-based proteins and collagen, are lacking at least one of the essential amino acids. Even different complete protein sources have differing levels of amino acids. 

One of our favorite amino acids, and the topic of conversation today, is glycine. Glycine is a conditionally essential amino acid. Our needs for glycine increase in cases of metabolic conditions, especially blood sugar dysregulation and chronically elevated blood sugar levels, as well as inflammatory diseases. Unfortunately, we often overlook glycine-rich protein sources. Keep reading to learn why glycine is so important for women and hormone health.

What Makes Glycine So Special?

Glycine is a superstar amino acid with significant benefits for hormone balance, metabolic function, glowing skin, and even nervous system support. 

1. Skin Health and Collagen Production

Glycine is a primary amino acid building block that makes up collagen, the structural protein that gives skin its elasticity and firmness. Its antioxidant and anti-inflammatory properties make glycine particularly important for skin health, supporting healthy aging, wound healing, and calming skin inflammation. 

Collagen and glycine also play pivotal roles in maintaining healthy bones and connective tissue, including tendons and ligaments. This is especially important for fertility as glycine supports the production of healthy cervical mucus and a robust uterine lining, and for pregnancy, as the uterus rapidly expands and develops additional connective tissue. These benefits also extend to the gut, with glycine being incredibly healing for the intestinal lining.

2. Nervous System Regulation and Stress Resilience

Another role of glycine is that it functions as a calming neurotransmitter, helping the brain and body to relax. In preliminary research it has been shown to lower core body temperature and enhance deep sleep, which we know is so important for supporting the nervous system and hormone health. In fact, glycine’s calming effect is why magnesium glycinate (magnesium bound to glycine) is often used to improve sleep.

Glycine’s impact on sleep and the nervous system has a ripple effect on hormones, supporting more balanced cycles, fewer PMS symptoms, and less inflammation. This can also help improve HPA-axis dysfunction, or an impaired stress response, helping to build better stress resilience.

3. Hormone Detox and Metabolic Support

Glycine plays a critical role in liver detoxification as a key building block of glutathione. Glutathione is the liver’s master antioxidant responsible for neutralizing harmful compounds that drive oxidative stress. Elevated oxidative stress not only depletes glutathione and increases glycine demand, but also contributes to a range of health issues, including thyroid dysfunction, irregular periods, metabolic disease, and even cancer.

The liver is also responsible for detoxifying or clearing excess estrogen and other waste products. When detox pathways are sluggish, these compounds can accumulate, leading to symptoms like painful periods, breast tenderness, mood swings, and histamine issues.

Beyond detoxification, glycine supports bile formation, which is essential for proper digestion, metabolism, and hormone regulation. It also plays a role in metabolic health, with low glycine levels linked to blood sugar imbalances and insulin resistance, which are common drivers of PCOS, thyroid dysfunction, and other hormone-related concerns.

Swap the Chicken Breasts: Glycine-Rich Proteins vs Muscle Meat

Muscle meats like chicken breast, turkey breast, and steak are complete protein sources, but are not great sources of glycine. Instead, they are rich in methionine, an essential amino acid that is vitally important in the body. However, too much methionine or insufficient B vitamin levels can actually turn methionine into homocysteine, an inflammatory compound and heart disease risk factor.

In contrast to muscle meats, bone-in proteins, slow-cooked proteins with more connective tissue (i.e. chuck roast or brisket), and bone broth are all great sources of glycine. When slow cooking tougher cuts of meat or roasting bone-in proteins, the glycine-rich collagen from the bones and connective tissue infuses into the meat.

You can add more glycine into your diet by swapping chicken breasts for bone-in chicken thighs. If that’s not available to you, consider cooking non-bone-in meats like chicken breast with glycine-rich bone broth. Bone broth-based soups or stews are another great way to pack in glycine for the whole family. Collagen peptides and gelatin can also easily be added into beverages, smoothies, and baked goods. 

For those who follow a plant-based diet, glycine is also found in tofu, edamame, lupini beans, and buckwheat (>1000mg glycine in 1 cup). For reference, 4-6 ounces of glycine-rich animal proteins typically yields two to three times the amount of glycine, so those following a plant-based diet may consider supplementing with collagen in lieu of adding other animal-based protein sources. 

The Bottom Line

Protein is essential for hormone health, but beyond how much protein you eat, we also want to consider the types of proteins. By incorporating more glycine-rich proteins like collagen, bone broth, and slow-cooked meats into your meals, you support not only hormone balance but also glowing skin, better sleep, fertility, and a calmer nervous system.

If you’re looking for a simple and easy way to get more glycine into your daily routine, consider a collagen-rich protein powder like our Functional FuelPRO protein powder. Functional FuelPRO is a hydrolyzed bone broth protein that is dairy-free, gluten-free, and is naturally packed with collagen, B vitamins, vitamin A, and vitamin D. It is a complete source of protein, so it has all of the essential amino acids along with a significant amount of glycine. Order your Functional FuelPRO today!

Written by Romana Brennan, MS, RDN