What You Need to Know About Collagen
Nazanin Abbaspour, PhD, RD
Collagen is the most abundant protein in your body—it gives structure and strength to your skin, bones, tendons, and joints. Starting in your late 20s, natural collagen production drops by about 1% each year, and by age 80, you may have lost up to 75% of it. Factors such as stress, smoking, poor diet, and aging all speed up this loss. (1, 2)
What Is Hydrolyzed Collagen?
Most collagen supplements contain hydrolyzed collagen (HC) or “collagen peptides.” These are smaller fragments of collagen (2–6 kDa) that are easier for the body to absorb. They’re derived from bovine, porcine, chicken, or marine sources and are detectable in the bloodstream within two hours after intake. (1, 3)
Skin Health
The strongest evidence for collagen is in skin health. Clinical studies show that taking 2.5–10 g per day for 8–12 weeks improves hydration, elasticity, and firmness while reducing wrinkles. (4, 5) Even lower doses (around 2.5 g) can help when paired with vitamin C and other nutrients. (6) Marine collagen may be slightly better absorbed than mammalian forms, but all types are effective. (4)
Joints and Bones
Collagen also supports joint comfort and bone strength. Both HC and undenatured type II collagen (UC-II) reduce joint pain and improve mobility in osteoarthritis. (7, 8) Typical doses range from 10–12 g/day (HC) or 40 mg/day (UC-II) for 3–6 months. Collagen helps protect cartilage, reduce inflammation, and stimulate the cells that build joint tissue. (8, 9) It may also modestly increase bone density when taken consistently. (3)
Heart and Metabolic Health
Taking at least 10 g/day of HC for 6–12 weeks may lower LDL (“bad”) cholesterol and triglycerides while raising HDL (“good”) cholesterol. (10) It can also slightly reduce systolic blood pressure—changes linked to meaningful heart health benefits. (11)
Higher doses (around 13 g/day) for 12 weeks have shown improvements in blood sugar and HbA1c, suggesting collagen may also support metabolic balance. (10)
Muscle and Body Composition
Collagen may help preserve lean body mass, especially when combined with exercise. Studies using ≥10 g/day for 6–12 weeks found reduced fat mass and improved muscle tone, particularly in older adults and those who train regularly. (10, 12)
Safety and Quality
Collagen supplements are generally safe and well-tolerated. Most products meet safety standards for heavy metals, though choosing third-party tested brands (USP, NSF, or ConsumerLab certified) is recommended to ensure purity, potency, and allergen transparency. (13)
For optimal quality and sustainability, select organic, pasture-raised terrestrial and wild-caught marine collagen sources whenever possible—these options tend to provide higher nutrient integrity and lower contaminant risk.
Key Takeaways
Skin: 2.5–10 g/day for 8–12 weeks improves hydration and elasticity.
Joints/Bones: 10–12 g/day HC or 40 mg/day UC-II for 3–6 months supports mobility and bone density.
Heart/Metabolic: ≥10 g/day for 6–12 weeks may improve cholesterol, blood pressure, and glucose control.
Muscle: ≥10 g/day with exercise supports lean mass and reduces fat.
Safety: Choose reputable third-party tested (USP, NSF, or ConsumerLab-certified), organic, pasture-raised, and wild-caught collagen brands for purity, sustainability, and transparency.
References
1. León-López, A., Morales-Peñaloza, A., Martínez-Juárez, et al., “Hydrolyzed Collagen—Sources and Applications,” Molecules, 24(22), 4031 (2019). https://doi.org/10.3390/molecules24224031
2. Gelse, K., Pöschl, E., Aigner, T., “Collagens–structure, function, and biosynthesis,” Adv Drug Deliv Re,. 28;55(12):1531-46 (2003). https://doi.org/10.1016/j.addr.2003.08.002
3. Al Hajj W, Salla M, Krayem M, et al., “Hydrolyzed collagen: Exploring its applications in the food and beverage industries and assessing its impact on human health – A comprehensive review,” Heliyon, 16;10(16):e36433 (2024). https://doi.org/10.1016/j.heliyon.2024.e36433
4. Pu, S.Y., Huang, Y.L., Pu, C.M., et al., “Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis,” Nutrients, 15, 2080 (2023). https://doi.org/10.3390/nu15092080
5. Zague, V., Pinheiro, A.L.T.A., Pinto, J.R. et al., “Oral Collagen Oligopeptides as a Modulator of Skin Health: A Comprehensive Evaluation of Clinical and Molecular Effects,” J Med Food, 28(9), 869-876 (2025). https://doi.org/10.1089/jmf.2024.0252.
6. Xerfan, E.M.S., Souza, M.R., Facina, A.S., et al., “Can Good Sleep Quality Enhance the Benefits of Oral Collagen Supplementation in the Prevention of Skin Aging? A Brief Report,” Arch Dermatol Res, 317(1), 340 9 (2025). https://doi.org/10.1007/s00403-025-03860-5.
7. Simental-Mendía, M., Ortega-Mata, D., Acosta-Olivo, C.A., et al., “Effect of Collagen Supplementation on Knee Osteoarthritis: An Updated Systematic Review and Meta-Analysis of Randomised Controlled Trials,” Clin Exp Rheumatol, 43(1), 126-134 (2025). https://doi.org/10.55563/clinexprheumatol/kflfr5.
8. Martínez-Puig, D., Costa-Larrión, E., Rubio-Rodríguez, N., Gálvez-Martín P., “Collagen Supplementation for Joint Health: The Link Between Composition and Scientific Knowledge,” Nutrients, 15(6), 1332 (2023). https://doi.org/10.3390/nu15061332.
9. Xu R, Wu J, Zheng L, Zhao M., “Undenatured Type II Collagen and Its Role in Improving Osteoarthritis,” Ageing Res Rev, 91, 102080 (2023). https://doi.org/10.1016/j.arr.2023.102080.
10. Jalili, Z., Jalili, F., Moradi, S., et al., “Effects of collagen peptide supplementation on cardiovascular markers: a systematic review and meta-analysis of randomised, placebo-controlled trials,” Br J Nutr, 14;129(5):779-794 (2023). https://doi.org/10.1017/S0007114522001301
11. Jurik, R., Stastny, P., “Role of nutrition and exercise programs in reducing blood pressure: A systematic review,” J Clin Med, 8(9), 1393 (2019). https://doi.org/10.3390/jcm8091393
12. Vijayan, D.K., Sreerekha, P.R., Dara, P.K., et al., “Antioxidant defense of fish collagen peptides attenuates oxidative stress in gastric mucosa of experimentally ulcer-induced rats,” Cell Stress Chaperones, 27(1), 45-54 (2022). https://doi.org/10.1007/s12192-021-01245-x
13. Wang, M., Liu, Y., Pallarés, N., et al., “Determination of Collagen Types and Mineral Contents in Fish Skin and Collagen-Containing Skin-Derived Protein Hydrolysates Before and After in Vitro Simulated Digestion,” Food Funct, 16(3), 1032-1040 (2025). https://doi.org/10.1039/D4FO03137G.
Nazanin Abbaspour, PhD, RD, is a registered dietitian and nutrition scientist specializing in integrative and functional nutrition. She works with Family Health Centers of San Diego and leads NutraLumina Integrative & Functional Nutrition.
