Collagen is a protein that provides structure to the body and is the most abundant protein in the human body, primarily found in the skin, bones, and connective tissues. As explained by Amy Shapiro, a registered dietitian and founder of the platform Real Nutrition, collagen is exclusively of animal origin and is found in the skin, bones, and connective tissues of chicken, pork, fish, and beef, as well as in bone broth. According to Abigail Collen, a clinical dietitian in outpatient consultations at Mount Sinai, collagen powders and dietary supplements are generally derived from bovine, porcine, or marine sources. For those following a vegetarian diet, collagen cannot be consumed directly since it comes from animal sources. Both Amy Shapiro and Abigail Collen agree that there is no true vegetarian collagen option. Pescetarians can opt for marine collagen, and ovo-vegetarians can turn to collagen derived from egg membranes, although these products are often harder to find. Some market products labeled as "vegan" collagen are not collagen per se but mixtures of amino acids and nutrients that support the body's natural production of collagen. Amy Shapiro explains that true collagen cannot be vegan because, by definition, collagen is an animal protein and does not naturally exist in any plant. To ensure adequate intake of collagen when following a vegetarian diet, the key is to prioritize foods and supplements that support the body's natural production of collagen. Amy Shapiro and Abigail Collen recommend a balanced vegetarian diet that provides enough protein and vitamin C, two elements that help the body produce more collagen. Amy Shapiro also advises consuming foods rich in zinc, copper, and amino acids. For vegetarians who include eggs in their diet, she notes that egg whites are rich in proline, an essential amino acid for collagen formation. Some plant-based supplements are formulated with vitamin C, biotin, and amino acids to support the body's collagen production. Abigail Collen suggests opting for marine collagen supplements if one is pescetarian, noting that marine collagen is structurally identical to bovine or porcine collagen and should have a similar effect on the body. This provides a viable option for those who consume fish but want to support their skin, joints, and overall connective tissue health without relying on non-vegetarian sources.