Marine Collagen: Why It May Be The Best Collagen For Digestion Issues & More

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Collagen is the most abundant protein in the human body. It's found in our tendons, ligaments, skin, muscles, bones, and blood vessels—and it plays a vital role in maintaining our overall structural integrity.

Unfortunately, our bodies produce about 1 percent less collagen with each passing year, and we're consuming far less of it from natural sources than we used to. This, of course, isn't a recipe for good health—and it's exactly why dozens of food and supplement companies are beginning to make products that help you fill the void.

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"For the majority of human history, our diet would have been much more collagen-rich than it is today. Because of this collagen deficiency, supplementation of collagen has been shown in the scientific literature to improve a wide variety of symptoms like lowered inflammation; improved cellular repair of joints, skin, and bone density; as well as blood sugar balance and hair growth," says Will Cole, D.C., mbg Collective member and best-selling author of the newly published Ketotarian.

Some of the first products to hit store shelves were bovine collagen peptides and gelatin, but now, we're seeing an increasing number of marine collagen powders (aka marine collagen peptides or marine hydrolyzed collagen), which cater to people avoiding meat. "Marine collagen is one of my favorite sources of clean protein," says Cole.

Here's a rundown of marine collagen health benefits, potential side effects, and how it compares to bovine collagen—plus, what to look for in a supplement.

So what is marine collagen?

Much of the marine collagen sold today is derived from fish like cod or snapper, specifically the skin and scales of these fish. Once the collagen protein is removed, it's broken down into smaller units of protein (or peptides) through a process called hydrolysis. These smaller bits make it so marine collagen peptides easily dissolve in hot or cold liquids, which makes it great for adding to your morning coffee, smoothie, or oatmeal. And yes, it's odorless and tasteless.

But what makes marine collagen a smart pick? In addition to being a quality source of protein and collagen for people avoiding meat or following a pescatarian-style diet, it's rich in a specific type of collagen that's commonly found in our own bodies: Type I collagen.

While at least 28 "types" of collagen can be found in the human body, three types—Type I, Type II, and Type III—comprise about 90 percent of all collagen in the body. Type I collagen, specifically, is found all over the body (except for cartilage) and is most highly concentrated in bone, ligaments, tendons, skin, hair, nails, and the gut lining.

As with all sources of collagen, though, the body doesn't simply absorb marine collagen whole and deliver it directly where it needs to go. It breaks the collagen down into its individual amino acids, which are then absorbed and utilized by the body. It's marine collagen's unique amino acid profile that makes it a truly beneficial source of protein. While it contains 18 amino acids, marine collagen is characterized by high levels of glycine, proline, and hydroxyproline. These amino acids, which are hard to find in meaningful quantities elsewhere, are crucial building blocks of skin collagen, tendons, and ligaments and have been shown to boost health in a number of other ways, such as decreasing inflammation and bolstering the immune system.

It's important to note that marine collagen contains only eight out of the nine essential amino acids, so it's not considered a complete protein. While it does contain amino acids that are often lacking in our modern diets, it's still important that you consume protein from a variety of sources.

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How is marine collagen different from bovine collagen?

One study suggests that the Type I collagen derived from fish may be around 1.5 times more bioavailable (or easier to break down and absorb) than bovine collagen due to its smaller protein particle size. So, if you have any digestive issues and you're trying to decide between marine and bovine collagen, marine may be the smarter choice. Otherwise, they're fairly similar in terms of benefits.

"In general, there aren't major differences between fish- or cow-derived collagen," says Cole. "I prefer a more plant-based, pescatarian keto way of eating, so I choose marine collagen. It mainly comes down to preference."

The health benefits of consuming marine collagen.

1. Improves the look and feel of skin.

While collagen production naturally declines as we age, slowly robbing us of that natural scaffolding that keeps our faces looking nice and plump, marine collagen may help slow the process. Animal research has found that consuming marine collagen increases dermal thickness on mice by increasing the number and activity of skin fibroblasts, or cells in the dermis that produce collagen and other fibers—and research on humans seems to confirm this effect. In one study, 15 percent of women who took a supplement containing hydrolyzed Type I collagen derived from tilapia had fewer facial lines and wrinkles after 60 days, 32 percent of the women had an improvement in the level of photoaging (skin damage caused by prolonged sun exposure), and 39 percent had improved skin moisture.

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2. Promotes quality sleep.

The most abundant amino acid in marine collagen, glycine, has promising sleep-enhancing perks. One review of research revealed that ingestion of glycine before bed improved self-perceived sleep quality among people prone to insomnia. It also suggested that glycine may help reduce core body temperature, which is associated with better sleep. Erratic spikes and dips in blood sugar can also interfere with quality sleep, while marine collagen (which often contains around 10 grams of protein per serving) can help even those out.

3. Helps balance blood sugar.

It's not just the protein content of marine collagen that helps keep your blood sugar on an even keel—high glycine levels may play a unique role in preventing those erratic spikes and dips and prevent type 2 diabetes. Research has shown a connection between low glycine levels and impaired glucose tolerance, and one study even found that people with type 2 diabetes were more likely to have low circulating blood levels of glycine.

4. Heals the gut and improves digestion.

Everything from too much stress to a poor diet has the potential to damage the delicate tissues lining the intestines. This contributes to "leaky gut," a condition in which foreign particles are able to enter your bloodstream and wreak havoc on your body, increasing inflammation and your risk for autoimmune diseases. The good news: Not only is marine collagen easily digestible, but it may help heal a damaged gut, thanks to its amino acid profile.

Two amino acids, glycine and glutamine, may be particularly helpful, as they both play a role in rebuilding the tissue that lines the digestive tract. Glycine is particularly helpful at taming inflammation, making it helpful for managing inflammatory gut conditions like IBS; and glutamine is necessary for the health and growth of the enterocytes, or epithelial cells, that line your gastrointestinal tract. "As the preferred fuel for these enterocytes, L-glutamine is one of the most powerful tools you can have in combating leaky gut syndrome," says Cole.

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5. Bolsters the effect of your workout.

Collagen is a concentrated source of the amino acid glycine, which helps your body produce creatine. In turn, creatine has been shown to help increase muscle mass and improve exercise performance. It's also a great source of proline, which acts as an antioxidant and helps prevent cellular damage that might cause post-workout achiness. While studies on marine collagen and exercise/muscle are lacking, one study found that taking bovine collagen peptides (which have a very similar amino acid profile to marine collagen) may increase muscle strength and fat loss when combined with resistance training. Additionally, marine collagen is easier to digest than other popular proteins, like whey, making it a smart addition to your pre-workout smoothie that's less likely to cause gastrointestinal upset.

6. Boosts bone strength.

While marine collagen doesn't contain the minerals you'd typically associate with bone health, one animal study suggests that it may help increase the absorption of calcium, phosphorus, and other minerals into the body. The increased absorption was also associated with increased activity of osteoblasts, cells in the bone responsible for synthesizing and mineralizing bone. Osteoblasts are also responsible for secreting collagen in order to create the unmineralized portion of the bone called the osteoid.

7. Promotes hair and nail growth.

Anecdotal evidence abounds of collagen's ability to increase hair and nail growth. While more research is needed in this area, one small study, the supplement Nutrafol, which contains 1,680 milligrams of marine collagen, increased hair growth rate, volume, and thickness. It may also boost fingernail growth and strength, but research in this area has typically involved bovine or porcine collagen, so more studies are needed.

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Are there any side effects?

Like bovine collagen, marine collagen really doesn't have many significant side effects. "As a functional medicine practitioner, one of the great things I have seen with marine collagen is how well it is tolerated by almost everyone," says Cole. "Where food reactivities are common today, this is one source of protein that not only agrees with most people but that people thrive taking."

In some studies, a few people have reported that it leaves a bad taste in their mouth, while others have reported minor bloating and digestive upset. But these results aren't the norm, and collagen is much more likely to help improve digestion than disrupt it. That said, you should definitely avoid marine collagen if you have an allergy to fish; and if you're currently taking any medication, check with your doctor to make sure collagen won't interfere with its effectiveness.

What to look for when you're choosing your marine collagen supplement.

While relatively safe to consume, you still need to be mindful of where your marine collagen supplement is coming from, especially since the FDA doesn't monitor collagen supplements (or any supplement) for safety or efficacy. "I always recommend people look for clean, wild-caught sources from a company that has independent nutritional and quality testing," says Cole.

A good strategy is to seek out a product that has been third-party verified to contain what the label says it contains and to be free of contaminants like mercury and other heavy metals (reputable groups that test supplement ingredients include NSF International, USP, and UL).

Because marine collagen is typically derived from fish skin or scales, you should also consider where those fish came from—both for your health and the health of the environment. Ideally, you'll seek out a marine collagen supplement from an established company that sources their collagen from sustainably caught fish (if they don't call this out on their label, that's typically a red flag). A number of marine collagen products have also been non-GMO-Project certified, which is typically another indicator of a good product.

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