Unfortunately, our bodies produce about 1% less collagen1 with each passing year, and we’re consuming far less of it from natural sources than we used to. This isn’t a recipe for good health—and is why dozens of food and supplement companies are beginning to make products that help you fill the void.* One of those being marine collagen.* As with all sources of collagen, 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.* While it contains 18 amino acids, marine collagen is characterized by high levels of glycine, proline, and hydroxyproline. 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. As for diet preferences, that’s pretty self explanatory: If you don’t eat meat, but you do eat fish, you’ll likely opt for marine. But if you do eat animal-products, you’ll likely opt for bovine. No matter what you choose, look for sustainable, clean sourcing. Animal research has found that consuming marine collagen helps maintains dermal thickness on mice by promoting 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 study3, women who took a supplement containing hydrolyzed Type I collagen derived from tilapia had better supported skin with diminished appearance of lines, photo-aging, and better maintained moisture levels.* Two amino acids, glycine and glutamine, may be particularly helpful, as they both play a role in supporting the tissue that lines the digestive tract.* Glycine is particularly helpful at maintaining inflammation4, making it helpful for managing inflammatory gut conditions;* and glutamine is necessary for the health of the enterocytes, or epithelial cells, that line your gastrointestinal tract.* The absorption was also associated with the 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.* “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 mbg contributor William Cole, D.C..* “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 studies10, 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. “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.