What Is Collagen and Is It Good for Fertility?

Collagen is the most abundant protein found in the human body. From the connective tissue that makes up tendons, ligaments, cartilage, and bones, to the structural components of the gut and skin, it’s a protein we can’t live without.

There are actually over 28 different types of collagen but, clinically, we tend to highlight four key types (watch for these “types” on the ingredients list of collagen products to understand how a particular collagen can serve your health goals); these are:

Collagen comes from animal products, but on supplement labels, you’ll likely either see “bovine” or “marine” collagen. Which one you choose depends on your goals and your lifestyle.

• Bovine collagen (sourced from cattle) is made up mostly of types I and III  collagen. These types support healthy skin, bones, and joints.  
• Marine collagen is sourced from fish. It’s rich in type I collagen, which is the most abundant type of collagen in our body, and key for skin, hair, nails, and wound healing. Compared to bovine, marine collagen peptides are smaller, which means they have better bioavailability (A.K.A., better absorption).

Those supplement sources of collagen we mentioned above? You can get some collagen directly—animal products include collagen.

• Chicken
• Beef
• Fish

Bone broth is a rich source of collagen because it’s made by slowly simmering animal bones, skin, and connective tissue. During this lengthy cooking process (typically 24 to 72 hours), the collagen naturally found in these tissues breaks down into gelatin and collagen peptides, which dissolve into the broth. This concentrated source of peptides is easy to digest, making bone broth a more bioavailable source of collagen compared to meat alone.

While plants don’t directly supply collagen, they provide the cofactors needed for the body to make its own. Nutrients like Vitamin C (found in peppers, oranges, and kiwis), copper (high in nuts and seeds), proline, and glycine (amino acids found in legumes like black beans) are excellent additions to your diet to boost the body’s own production of collagen.

Collagen is an essential protein for our health and longevity. Because it’s a protein involved in structural components of our body, it’s tied to visible and functional markers of aging and health. Starting in our mid-twenties, collagen production begins to naturally decline by about 1% each year. Lower collagen levels are associated with signs of aging like wrinkles, sagging skin, and slower wound healing (And sun exposure can worsen these effects.)

But it’s not just those cosmetic factors. Collagen is important for connective tissue resilience, which is the framework for most of our functional health (think: less pain, better mobility, lower inflammation, and less body fat). Because of this, we might say that collagen, indirectly, supports mood, sleep, and general well-being, too.

Fortunately, we can help mitigate the effects of declining collagen levels by relying on collagen-rich foods, nutrient cofactors to boost the body’s own collagen production, and supplementation.

• Hair, skin, and nails, by synthesizing keratin (a protein that provides them with structure and strength) and increasing specialized cells called fibroblasts that boost hydration 
• Joint function and mobility, by providing the raw materials (amino acids) to rebuild tendons, ligaments, and bony matrix
• Inflammation, pain, and recovery by decreasing pro-inflammatory processes 
• Heart health, by maintaining vascular structure and improving cardiovascular function 
• Gut health, by acting as a prebiotic

Supplementing also contributes to total dietary protein requirements. In fact, research conducted on elderly men at risk for sarcopenia (muscle wasting) found that when collagen peptides were consumed after resistance training, muscle mass improved. The key: taking enough (between 2.5 to 10 g per day) for 8 to 12 weeks. 

The human body requires nine essential amino acids to function. These amino acids must come from our diets since the body can’t make them on its own. Animal-based foods contain all nine of these essential amino acids (think: eggs, beef, chicken, fish), and some plant-based foods do, too (like soy, quinoa, and hemp hearts). Collagen, on the other hand, is formed by three amino acids (glycine, proline, and hydroxyproline), making it an incomplete source of protein.

Collagen plays a supporting role in fertility by providing structural integrity to the reproductive organs, key amino acids for cellular energy, and nutritional building blocks for healthy ovulation and implantation. So while collagen isn't a direct fertility treatment, it matters—and there's good reason to consider it as part of your preconception nutrition.

In females, collagen maintains the integrity of the ovaries, uterus, and endometrial lining—tissues essential for ovulation, implantation, and the luteal phase of the menstrual cycle. The amino acids that make up collagen—glycine and proline—also support mitochondrial function (cellular energy), which is important for egg quality. Glycine in particular becomes increasingly essential during pregnancy, when demand for fetal development rises significantly.

In males, collagen-rich connective tissue supports the testicular structure of Leydig cells, which produce testosterone, and is associated with sperm motility. That said, direct clinical evidence linking collagen supplementation to improved male fertility outcomes is limited.
While no clinical trials directly connect collagen supplementation to improved pregnancy rates, collagen provides foundational nutritional support for overall reproductive health—for both females and males trying to conceive.

Generally, collagen is considered safe in pregnancy and while breastfeeding, but research is limited. Supplementing with collagen may combat stretch marks, support skin elasticity, and improve wound healing through pregnancy, though we need more clinical trials to confirm its effectiveness and safety. As always, it’s important to speak with your healthcare provider before starting any supplement.

And whether pregnant or not, always look for third-party tested collagen products. This ensures the product is free of heavy metals, bacteria, or other harmful byproducts.