February 2021 Issue
Supplements: Collagen Supplements
By Carrie Dennett, MPH, RDN, CD
Vol. 23, No. 2, P. 16
Our bodies make collagen — do we need to eat it, too?
The supplement industry is worth $35 billion per year in the United States, and one of the current stars in the supplement universe is collagen, with consumers purchasing $98 million worth of collagen supplements in 2018, a spending level that’s on the rise.1 Much of the hype around collagen supplements comes from its purported ability to reduce signs of skin aging, manage osteoarthritis symptoms, and improve digestive health.
“The growth in collagen sales reflects American’s interest in trying to improve gut health, reduce pain, and hold on to youthfulness as long as possible,” says Julie Stephanski, MEd, RDN, CSSD, LDN, CDCES, FAND, a spokesperson for the Academy of Nutrition and Dietetics, in Baltimore. But what is supplemental collagen, and does the science match the hype?
What Is Collagen?
Collagen is a family of proteins that are the primary structural component of connective tissues, such as cartilage, tendons, and skin. There are at least 30 types of collagen, each with a unique amino acid composition and structure, but glycine, proline, and hydroxyproline are the main three collagen amino acids.2
Collectively, collagen accounts for about one-third of the protein in the human body and about 75% of the skin’s dry weight.2,3 About 90% of collagen is type I, which is found in the skin, tendons, ligaments, organs, teeth, and bone. Type II is found in the cartilage that cushions our joints. Our bodies make collagen, but this ability starts decreasing in our 20s and is associated with visible skin aging.4 Excess sun exposure, smoking, environmental pollution, alcohol abuse, and a diet low in vegetables and fruits can increase oxidative stress, which also inhibits collagen production.2,4
The collagen in supplements generally comes from cows, pigs, chickens, and fish.3 When denatured by heat, collagen becomes gelatin,2 and most supplemental collagen has been hydrolyzed—broken down into short chains of amino acids called peptides—to make it water soluble. Hydrolyzed collagen can be further degraded into more bioactive dipeptides and tripeptides.4 Whereas proteins and longer peptides are degraded during digestion, di- and tripeptides can be absorbed in the small intestine.
In vitro studies demonstrate that ingesting hydrolyzed collagen induces collagen synthesis,2 but does this translate to observable health benefits?
Skin and Gut Health
A 2019 University of California systematic review of 11 randomized placebo-controlled human studies that enrolled a total of 805 patients concluded that preliminary results are promising for the short- and long-term use of oral collagen supplements for reducing signs of skin aging—increasing skin elasticity, hydration, and dermal collagen density—and boosting wound healing.2
However, it’s unclear what dose of collagen is necessary to improve skin concerns, and many products contain other ingredients that also could have skin benefits.2 For example, two recent, combined industry-funded randomized, double-blinded placebo-controlled studies in Germany found that taking a supplement containing bovine collagen peptides, acerola fruit extract, vitamin C, zinc, biotin, and a vitamin E complex for three months significantly improved skin hydration, elasticity, roughness, and density in a total of 132 healthy women aged 35 and older.5,6 Many—but not all—of these changes were retained one month post treatment, pointing to the need to take these supplements long term.
Some of the least substantiated claims are for gut health. “Collagen supplementation has especially grown in popularity for support of intestinal permeability and autoimmune issues, especially among proponents of the autoimmune protocol diet, or AIP,” Stephanski says. The supposed benefits center on the use of glycine by the cells that line the intestine. “This theory assumes that either humans are not consuming enough glycine or that consuming additional glycine will benefit the lining of the [gastrointestinal] tract. While supplementation is likely not harmful, more research is needed to demonstrate that the amino acid profile of collagen specifically targets this condition.”
Toronto-based Abby Langer, RD, owner of abbylangernutrition.com, says the claims about hydrolyzed collagen around strengthening hair and nails, improving gut health, reducing wrinkles, and improving skin appearance are the most questionable. “The research used to ‘prove’ these claims is mostly in animals and lab dishes or sponsored by the collagen industry.” Sometimes, the only “evidence” is anecdotal. “Collagen does not ‘heal’ the leaky junctions between cells in the gut, and it certainly doesn’t go straight to your hair or nails to make them shinier—that’s not how your body works. All in all, the claims made about collagen are mostly ahead of the science.”
Looking at osteoarthritis, an industry-sponsored, double-blinded, multicenter trial randomized 191 participants with knee osteoarthritis to take a type II collagen supplement, a glucosamine and chondroitin supplement, or a placebo for 180 days. Those in the collagen group demonstrated significant decreases in pain, stiffness, and physical function limitations.7 However, a meta-analysis of randomized placebo-controlled trials found that collagen supplements produce a significant decrease in osteoarthritis stiffness but not in pain or functional limitations.8
What about joint pain and recovery in athletes? In one small randomized double-blinded, placebo-controlled trial of 50 amateur competitive athletes with chronic ankle instability, those who received a daily collagen supplement for six months reported significant improvements in ankle function, and a significant decrease in ankle injuries at a three-month follow-up.9 However, there’s a lack of significant research in this area, especially in elite athletes.10,11
Stephanski says she has seen false claims that the International Olympic Committee (IOC) endorsed collagen peptides as having the potential to assist with training capacity, recovery, muscle soreness, and injury management. However, the cited 2018 IOC statement only comments that gelatin and collagen supplements “appear to be low risk” and points to the lack of quality data for collagen supplementation, adding that functional benefits, recovery from injury, and other effects in elite athletes are unknown.12
“If an athlete doesn’t allow enough time to rest and recover, no protein supplement can repair damaged tissue,” Stephanski says.
On that note, collagen powders often touted as a protein boost post workout—or in morning coffee—may not be the best choice. “Collagen protein powder doesn’t have all of the amino acids we need, so it’s not a complete protein like soy or whey protein powders are,” Langer says. “I think people should also know that collagen is sourced from fish scales, cow, and pig parts like tendons, skin, and bones, and egg shells. I don’t know about you, but I’m not a fan of tendon in my coffee.”
Stephanski says when collagen is compared with whey protein on muscle synthesis post exercise, whey protein has been the clear winner. “The quality of a protein supplement is often based on the number of amino acids, the digestibility, and the ultimate utilization by muscle cells. In comparing these factors, whey protein provides the maximum bioavailability for muscle recovery and repair.”13
The FDA doesn’t regulate dietary supplements, so while collagen supplements appear to be safe, there are concerns about the purity of active ingredients and whether they may contain unlisted components.1 “Collagen is probably safe to consume, although there have been some isolated issues with collagen powder and heavy metal contamination,” Langer says.
Stephanski says it’s important to avoid supplements manufactured in countries documented to contain high amounts of contamination with heavy metals, such as lead. She recommends reviewing dietary supplements via the Natural Medicines Database, looking on the FDA website to see whether the manufacturer has had any product recalls, and researching companies to ensure they employ Good Manufacturing Practices.
What should dietitians consider before jumping on the collagen bandwagon? “To me, collagen is comparable to a condiment such as ketchup that you’re adding on top of a hamburger,” Stephanski says. “Eaten alone, it really doesn’t make much of a meal. You must have a good overall diet first with sufficient energy and protein before you can reap the benefits of any type of dietary add-on such as a supplement. Collagen alone can’t replace the wide variety of amino acids that we need to maintain our bodies.”
Langer says regardless of individual nutrition philosophy, dietitians should avoid making unproven claims and relying on low-quality research. “If a diet only has preliminary research behind it, that should be evident in our content; we should never be promoting that preliminary research as if it’s established fact,” she says. “As dietitians, we need to be better at vetting the claims that companies want us to use to sell products, and understand that stretching the truth, or trying to pass off animal or in vitro studies as solid evidence, isn’t ethical.”
— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Holistic Guide to Optimal Wellness.
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13. Oikawa SY, Kamal MJ, Webb EK, McGlory C, Baker SK, Phillips SM. Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial. Am J Clin Nutr. 2020;111(3):708-718.