he abundance of collagen in the skin is responsible for its youthful appearance. It is not only the major protein in the human body. Collagen is also the most abundant protein in the animal kingdom. It is believed that impaired synthesis and degradation of collagen could be countered by ingesting foods rich in collagen. Among the multiple sources of collagen, fish collagen is recognized for its superior health benefits.
Collagen is present in the extracellular matrix and in the connective tissues. It is the dominant insoluble fibrous protein found in the human body. It comprises almost 30% of the total body proteins. The human body contains at least 16 types of collagen. However, types I, II and III are the prominent collagens comprising 80 to 90 percent of the whole body collagen. These collagen molecules bind to form thin fibrils of similar structure. In addition to fibroblasts that are primarily responsible for secretion of collagen molecules, numerous epithelial cells are also associated with collagen synthesis. Regardless of the type of collagen and the structures formed by them, their sole function is to enable the body tissues to withstand stretching. 
Importance of Dietary Collagen
Collagen is present in the skin, bones, tendons, ligaments, muscles, intestinal linings, blood vessels, organs and various connective tissues. Hence, depletion of collagen, not only affects your skin making it wrinkled and saggy, it also affects your joints and muscles and is known to cause gastrointestinal disorders. Though aging is the major cause of collagen degradation, poor diet is known to impair collagen synthesis. Your body needs amino acids, vitamin C, copper and zinc to produce collagen. A diet deficient in protein and vitamins and minerals decrease collagen synthesis.
Furthermore, aging reduces the absorption of nutrients and slows down collagen production, thereby necessitating intake of collagen-boosting foods and supplements. Bone broth produced by slowly simmering bones of chicken, animals or fish in water over a long time is known to be the best source of dietary collagen. Ready-made bone broths are available in the grocery stores. However, nowadays, collagen supplements are the preferred sources of dietary collagen. They are usually available in the form of collagen peptide or hydrolyzed collagen powder. The flavorless collagen powder can be combined with soups, smoothies, sauces, and beverages. Collagen is also used topically and is added to skin creams. It is known to form a protective barrier on the skin that inhibits water loss and protects from environmental elements. 
Why Fish Collagen is a Superior Source of Collagen
Owing to the benefits of collagen in maintaining healthy skin, bones, and tendons, collagen obtained from animals and fish are widely used in food, pharmaceutical, cosmetic and biomedical industries and in tissue engineering. Despite the popularity of bovine and porcine skin and bones as the sources for the production of commercial collagen, risks of contracting transmissible spongiform encephalopathy from bovines affected by bovine spongiform encephalopathy in addition to religious issues have increased the use of fish collagen.
Fish collagen is considered to be a safer alternative to mammalian collagen. Fish bones, skin, scales and viscera are rich in collagen. Commercial fish collagens are primarily obtained from the wastes of the fish processing industry. Apart from marine and freshwater fishes, aquatic animals such as squid and octopus are important sources of collagen. Notwithstanding the differences between the physical and chemical properties of mammalian collagen and fish collagen, fish collagen is known to be safer as it does not entail risk of contracting transmittable diseases. 
The mammalian collagen comprises of 33% glycine, 11% alanine, 12% proline and 9% hydroxyproline. It does not contain tryptophan and sulfur-containing amino acids. Despite slight variations in the compositions of the amino acids, a number of studies have shown that the composition of amino acids in fish collagen is almost similar to that of mammalian collagen. Glycine, the most abundant amino acid in collagen, comprises more than 30% of all the amino acids in fish collagen. It is especially concentrated in collagen derived from fish skin, scales and muscles. However, proline and hydroxyproline contents in fish collagen are slightly lower than those in mammalian collagen.
The amino acid proline accounts for 10.5% and hydroxyproline comprises 7% of all the amino acids in fish collagen. However, marine collagen contains higher amounts of glutamine or glutamic acid (GLX) and alanine (ALA) than mammalian collagen. Marine collagens are easily extractable, and, therefore, available in large amounts. Hence, they are cheaper than the mammalian collagens. Furthermore, they are soluble in water, whereas mammalian collagen can dissolve only in organic solvents. Because of its cell growth potential, biocompatibility, high biodegradability, and low antigenicity, fish collagen is widely used as a bioactive material that works as an effective scaffold and carrier in biomedical applications, cosmetics, and food supplements. 
Benefits of Fish Collagen
The following are the various health benefits of Fish Collagen:
1. Helps in Fighting Skin Aging
Currently, collagen is a popular ingredient in high-end skin and hair care products. Marine collagen-based cosmeceutical products are used as skin lotions and creams, facial cleansers, hair shampoos and conditioners, and various hair treatment products. They are known to possess moisturizing and protective properties.  Partially hydrolyzed a collagen is a non-gelling form of gelatin, used in shampoos, conditioners, lipsticks and fingernail preparations. It is also included in anti-aging products and is believed to serve as a source of collagen for the aging skin.
In a study with fish scale collagen peptides derived from tilapia, researchers found that application of the collagen-containing product twice daily for 30 days helped in enhancing the skin’s moisture content and elasticity. The effectiveness of the fish-collagen based product was directly proportional to the collagen dosage. Topical application of fish collagen helped in increasing the production of fibroblasts and stimulated procollagen synthesis. Moreover, the larger molecular weight fish scale collagen peptides could easily penetrate the skin. Fish collagen peptides can, therefore, help in rejuvenating the skin when used topically. 
In Japan and other Asian cultures, collagen peptides are widely consumed to combat skin aging. The beneficial effect of marine collagen supplementation on skin health has been demonstrated in experimental studies. Collagen polypeptides derived from cod skin was found to be effective in protecting the skin from ultraviolet A-induced skin damage. Supplementation with collagen polypeptides helped in preserving moisture and lipid in the skin.
Furthermore, it helped in repairing the endogenous elastin and collagen and support the healthy balance of type I and type III collagen in the skin.Collagen peptide is also known to boost the skin’s anti-aging defense. Ingesting marine collagen is also believed to inhibit collagen breakdown and improve collagen homeostasis in the aged skin. Oligopeptides produced following digestion of collagen polypeptides can help to stimulate the fibroblasts to increase collagen and other components of connective tissues. 
2. Helps in Diabetes Management
Experimental studies suggest that supplementation with marine collagen peptides can help in improving glucose metabolism and insulin resistance. The beneficial effects of marine collagen peptides are believed to be due to their anti-inflammatory and antioxidant activities.  In a clinical study, diabetic patients who took 13 g of marine collagen peptides daily had significantly lower levels of fasting glucose, fasting blood insulin, glycated hemoglobin HbA1c, total cholesterol, low-density lipoprotein, total triglyceride, and free fatty acids.
Furthermore, fish collagen helped in increasing insulin sensitivity and HDL or good cholesterol level.  Oral administration of wild marine fish collagen hydrolysate can help in modulating the serum levels of the hormones leptin, adiponectin and resistin that are closely associated with pathogenesis of diabetes. 
3. Helps Reduce High Blood Pressure
Fish collagen is believed to be beneficial for people with hypertension or high blood pressure. Hypertension is known to increase risks of stroke, myocardial infarction, atherosclerosis, congestive heart failure, and end-stage kidney diseases. Collagen obtained from fish skin, cartilage and scales possess powerful angiotensin-converting enzyme (ACE) inhibitors that help in lowering the elevated blood pressure level. The ACE-inhibitory activity of collagen is attributed to its peptides, hydrophobic amino acids, and the high proline content. 
4. Helps Improve Bone Mineral Density
One-third of the female population and one-fifth of the male population worldwide are believed to be suffering from osteoporosis or loss of bone mineral density. According to preclinical in vitro studies, collagen peptides can improve the micro-architecture of the bone, bone metabolism, and biochemical resistance, and increase the organic components of the bones.
In a clinical study, supplementation with collagen peptides has been found to be effective in improving the bone mineral density in postmenopausal women with primary age-related reduction of bone mineral density. The study suggests that collagen supplementation can stimulate the formation of bone cells and slow down bone degradation.  Fish collagen peptides support gene expression of a number of collagen-modifying enzymes that has a positive effect on osteoblastic cells. 
5. Helps Heal Wound
Experimental studies suggest that marine collage peptides can help in speeding up healing of wounds. In a study on rodents, researchers found that oral administration of collagen peptides derived from chum salmon stimulated post-cesarean wound healing. Marine collagen promoted the formation of capillaries, collagen fibers, and fibroblasts. 
6. Fights Pathogens
An antimicrobial peptide has been identified in fish collagen. The peptide known as collagen in is capable of suppressing the growth of Staphylococcus aereus. S. aureus is a major pathogen associated with skin infections, respiratory infections, and food poisoning. 
7. Source of Antioxidant
The peptides isolated from marine fish collagen are known for their antioxidant activities. The antioxidant activities of marine fish collagen and gelatin peptides are found to be more potent than alpha-tocopherol, a form of vitamin E. They can, therefore, help in inhibiting lipid peroxidation, scavenging free radicals and chelating transition metal ions. 
8. Reduces Liver Injury
Liver injury associated with alcohol intake can be minimized with the help of marine collagen peptides. In a study using rodent model, researchers found that oral administration of marine collagen peptides helps in reducing the elevated levels of total cholesterol and triacylglycerol (TAG) and inhibited changes in the antioxidant levels in the liver. These observations suggest that through their antioxidant activities and by improving lipid metabolism marine collagen peptides are capable of diminishing risks of early alcoholic liver injury. 
9. Helps in Ulcerative Colitis
Ulcerative colitis is a chronic disorder of the digestive tract. It causes inflammation and ulcers that develop on the innermost lining of the colon and rectum. Abdominal pain, rectal bleeding, diarrhea, fatigue and weight loss are common symptoms of ulcerative colitis.  According to an experimental study, collagen peptide derived from fish scale can help in attenuating the symptoms of ulcerative colitis. The study revealed that fish collagen has anti-inflammatory property that helps in suppressing colon inflammation. 
Fish Collagen Supplements and Fish Broth
Marine collagen is usually available in powdered form. The best quality marine collagen is usually obtained from wild-caught fish. It is known to be one of the cleanest and most bioavailable sources of protein. Powdered fish collagen can be taken along with almond or coconut milk. 
If marine collagen supplement is unavailable, you can still enjoy the benefits of fish collagen by devouring a bowl of homemade fish broth. Fish broth is a rich source of collagen extracted from fish bones and fish heads. Carcasses of low-fat white fish such as cod, halibut, rockfish or turbot are best suited for preparing delicious fish broth. Although collagen-rich broth can also be prepared with oily fish such as tuna and salmon, but cooking them for a long time tends to create off-flavors.  Fish collagen melts and dissolves quickly at lower temperatures than mammalian collagen. Therefore, unlike broths prepared with mammalian or avian bones, fish bones should not be simmered for a long time. By simmering the fish carcasses in water at a temperature below the boiling point, the fish collagen can be extracted from the bones in about half an hour. 
Possible Side Effects
Although fish collagen is usually considered safe for consumption, a study in Japan suggests sensitivity to collagen as a possible side effect of fish collagen intake. The risk is higher in the case of individuals with fish allergy. Almost 50% of individuals with fish allergy were found to be sensitive to fish collagen.