Collagen Studies

Collagen Studies from Dr. Rhonda Patrick

Hydrolyzed Collagen – a great overview article by Dr. Rhonda Patrick based on the following sources:

  1.  ^  Ricard-Blum, S. The Collagen Family Cold Spring Harbor Perspectives in Biology 3, no. 1 (December 2010): a004978–a004978. 
  2.  ^  Ryazanov, Alexey G, and Bradley S Nefsky. Protein turnover plays a key role in aging Mechanisms of Ageing and Development 123, no. 2-3 (January 2002): 207–13. 
  3.  ^  Khan, Ruby, and MohdHaroon Khan. Use of collagen as a biomaterial: An update Journal of Indian Society of Periodontology 17, no. 4 (2013): 539. 
  4. a b  Kadler, K. E., C. Baldock, J. Bella, and R. P. Boot-Handford. Collagens at a glance Journal of Cell Science 120, no. 12 (May 2007): 1955–58. 
  5.  ^  Mienaltowski, Michael J., and David E. Birk. Structure, Physiology, and Biochemistry of Collagens Advances in Experimental Medicine and Biology In , 5–29. Springer Netherlands, 2013. 
  6. a b c d  León-López, Arely, Alejandro Morales-Peñaloza, Víctor Manuel Martínez-Juárez, Apolonio Vargas-Torres, Dimitrios I. Zeugolis, and Gabriel Aguirre-Álvarez. Hydrolyzed Collagen Sources and Applications Molecules 24, no. 22 (November 2019): 4031. 
  7.  ^  Liu, Dasong, Mehdi Nikoo, Gökhan Boran, Peng Zhou, and Joe M. Regenstein. Collagen and Gelatin Annual Review of Food Science and Technology 6, no. 1 (April 2015): 527–57. 
  8.  ^  Li, Peng, and Guoyao Wu. Roles of dietary glycine, proline, and hydroxyproline in collagen synthesis and animal growth Amino Acids 50, no. 1 (September 2017): 29–38. 
  9.  ^  Ramshaw, John A.M, Naina K Shah, and Barbara Brodsky. Gly-X-Y Tripeptide Frequencies in Collagen: A Context for Host Guest Triple-Helical Peptides Journal of Structural Biology 122, no. 1-2 (1998): 86–91. 
  10.  ^  Subhan, Fazli, Muhammad Ikram, Adeeb Shehzad, and Abdul Ghafoor. Marine Collagen: An Emerging Player in Biomedical applications Journal of Food Science and Technology 52, no. 8 (December 2014): 4703–7. 
  11.  ^  Alcock, Rebekah D., Gregory C. Shaw, and Louise M. Burke. Bone Broth Unlikely to Provide Reliable Concentrations of Collagen Precursors Compared With Supplemental Sources of Collagen Used in Collagen Research International Journal of Sport Nutrition and Exercise Metabolism 29, no. 3 (May 2019): 265–72. 
  12.  ^  Silk, D. B. A., G. K. Grimble, and R. G. Rees. Protein digestion and amino acid and peptide absorption Proceedings of the Nutrition Society 44, no. 1 (February 1985): 63–72. 
  13.  ^  Koopman, René, Nico Crombach, Annemie P Gijsen, Stéphane Walrand, Jacques Fauquant, Arie K Kies, Sophie Lemosquet, Wim HM Saris, Yves Boirie, and Luc JC van Loon. Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein The American Journal of Clinical Nutrition 90, no. 1 (May 2009): 106–15. 
  14.  ^  Skov, Kathrine, Mikkel Oxfeldt, Rebekka Thøgersen, Mette Hansen, and Hanne Christine Bertram. Enzymatic Hydrolysis of a Collagen Hydrolysate Enhances Postprandial Absorption Rate A Randomized Controlled Trial Nutrients 11, no. 5 (May 2019): 1064. 
  15.  ^  Oesser, Steffen, Milan Adam, Wilfried Babel, and Seifert Jürgen. Oral Administration of 14C Labeled Gelatin Hydrolysate Leads to an Accumulation of Radioactivity in Cartilage of Mice (C57/BL) The Journal of Nutrition 129, no. 10 (October 1999): 1891–95. 
  16.  ^  Watanabe-Kamiyama, Mari, Muneshige Shimizu, Shin Kamiyama, Yasuki Taguchi, Hideyuki Sone, Fumiki Morimatsu, Hitoshi Shirakawa, Yuji Furukawa, and Michio Komai. Absorption and Effectiveness of Orally Administered Low Molecular Weight Collagen Hydrolysate in Rats Journal of Agricultural and Food Chemistry 58, no. 2 (January 2010): 835–41. 
  17. a b  Baumann, L. Skin ageing and its treatment The Journal of Pathology 211, no. 2 (January 2007): 241–51. 
  18.  ^  Sionkowska, Alina, Sławomir Skrzyński, Krzysztof Śmiechowski, and Agata Kołodziejczak. The review of versatile application of collagen Polymers for Advanced Technologies 28, no. 1 (June 2016): 4–9. 
  19.  ^  Aguirre-Cruz, Gabriel, Arely León-López, Verónica Cruz-Gómez, Rubén Jiménez-Alvarado, and Gabriel Aguirre-Álvarez. Collagen Hydrolysates for Skin Protection: Oral Administration and Topical Formulation Antioxidants 9, no. 2 (February 2020): 181. 
  20.  ^  Proksch, E., D. Segger, J. Degwert, M. Schunck, V. Zague, and S. Oesser. Oral Supplementation of Specific Collagen Peptides Has Beneficial Effects on Human Skin Physiology: A Double-Blind, Placebo-Controlled Study Skin Pharmacology and Physiology 27, no. 1 (2014): 47–55. 
  21. a b  Schwartz, S. R., K. A. Hammon, A. Gafner, A. Dahl, N. Guttman, M. Fong, and A. G. Schauss. Novel Hydrolyzed Chicken Sternal Cartilage Extract Improves Facial Epidermis and Connective Tissue in Healthy Adult Females: A Randomized, Double-Blind, Placebo-Controlled Trial Altern Ther Health Med 25, no. 5 (September 2019): 12–29. 
  22.  ^  and, and. The Roles of Vitamin C in Skin Health Nutrients 9, no. 8 (August 2017): 866. 
  23. a b  Kim, Do-Un, Hee-Chul Chung, Jia Choi, Yasuo Sakai, and Boo-Yong Lee. Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study Nutrients 10, no. 7 (June 2018): 826. 
  24.  ^  Czajka, Anna, Ewa M. Kania, Licia Genovese, Andrea Corbo, Giovanni Merone, Cecilia Luci, and Sara Sibilla. Daily oral supplementation with collagen peptides combined with vitamins and other bioactive compounds improves skin elasticity and has a beneficial effect on joint and general wellbeing Nutrition Research 57 (September 2018): 97–108. 
  25.  ^  Sibilla, Sara, and Maryam Borumand. Daily consumption of the collagen supplement Pure Gold Collagen&regthsemicolon reduces visible signs of aging Clinical Interventions in Aging , October 2014, 1747. 
  26.  ^  Park, Joosang, and Schwartz. Ingestion of BioCell Collagen&regthsemicolon, a novel hydrolyzed chicken sternal cartilage extractthsemicolon enhanced blood microcirculation and reduced facial aging signs Clinical Interventions in Aging , July 2012, 267. 
  27.  ^  Bullock, Jacqueline, Syed A.A. Rizvi, Ayman M. Saleh, Sultan S. Ahmed, Duc P. Do, Rais A. Ansari, and Jasmin Ahmed. Rheumatoid Arthritis: A Brief Overview of the Treatment Medical Principles and Practice 27, no. 6 (2018): 501–7. 
  28.  ^  Bello, Alfonso E., and Steffen Oesser. Collagen hydrolysate for the treatment of osteoarthritis and other joint disorders:a review of the literature Current Medical Research and Opinion 22, no. 11 (October 2006): 2221–32.×148373. 
  29. a b  Schauss, Alexander G., Jerome Stenehjem, Joosang Park, John R. Endres, and Amy Clewell. Effect of the Novel Low Molecular Weight Hydrolyzed Chicken Sternal Cartilage Extract, BioCell Collagen, on Improving Osteoarthritis-Related Symptoms: A Randomized, Double-Blind, Placebo-Controlled Trial Journal of Agricultural and Food Chemistry 60, no. 16 (April 2012): 4096–4101. 
  30. a b  García-Coronado, Juan Mario, Lorena Martínez-Olvera, Rodrigo E. Elizondo-Omaña, Carlos Alberto Acosta-Olivo, Félix Vilchez-Cavazos, Luis Ernesto Simental-Mendía, and Mario Simental-Mendía. Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of randomized placebo-controlled trials International Orthopaedics 43, no. 3 (October 2018): 531–38. 
  31.  ^  Lugo, James P., Zainulabedin M. Saiyed, and Nancy E. Lane. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study Nutrition Journal 15, no. 1 (December 2015). 
  32.  ^  Bakilan, Fulya, Onur Armagan, Merih Ozgen, Funda Tascioglu, Ozge Bolluk, and Ozkan Alatas. Effects of Native Type II Collagen Treatment on Knee Osteoarthritis: A Randomized Controlled Trial The Eurasian Journal of Medicine 48, no. 2 (July 2016): 95–101. 
  33.  ^  Crowley, David C., Francis C. Lau, Prachi Sharma, Malkanthi Evans, Najla Guthrie, Manashi Bagchi, Debasis Bagchi, Dipak K. Dey, and Siba P. Raychaudhuri. Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial International Journal of Medical Sciences , 2009, 312–21. 
  34.  ^  Tong, Tong, Wei Zhao, Ying-Qi Wu, Yan Chang, Qing-Tong Wang, Ling-Ling Zhang, and Wei Wei. Chicken type II collagen induced immune balance of main subtype of helper T cells in mesenteric lymph node lymphocytes in rats with collagen-induced arthritis Inflammation Research 59, no. 5 (October 2009): 369–77. 
  35.  ^  Wang, H., Z. Feng, J. Zhu, and J. Li. [Zaocys type II collagen regulates mesenteric lymph node Treg/Th17 cell balance in mice with collagen-induced arthritis] Nan Fang Yi Ke Da Xue Xue Bao 34, no. 5 (May 2014): 622–26. 
  36.  ^  Barnett, Martha L., Daniel Combitchi, and David E. Trentham. A pilot trial of oral type II collagen in the treatment of juvenile rheumatoid arthritis Arthritis & Rheumatism 39, no. 4 (April 1996): 623–28. 
  37.  ^  Crowley, D. C., F. C. Lau, P. Sharma, M. Evans, N. Guthrie, M. Bagchi, D. Bagchi, D. K. Dey, and S. P. Raychaudhuri. Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial Int J Med Sci 6, no. 6 (October 2009): 312–21. 
  38. a b c  Wei, Wei, Ling-Ling Zhang, Jian-Hua Xu, Feng Xiao, Chun-De Bao, Li-Qing Ni, Xing-Fu Li, et al. A multicenter, double-blind, randomized, controlled phase III clinical trial of chicken type II collagen in rheumatoid arthritis Arthritis Research & Therapy 11, no. 6 (2009): R180. 
  39.  ^  Sieper, Joachim, Sonja Kary, Helmut Sörensen, Rieke Alten, Ulrich Eggens, Werner Hüge, Falk Hiepe, et al. Oral type II collagen treatment in early rheumatoid arthritis. A double-blind, placebo-controlled, randomized trial Arthritis & Rheumatism 39, no. 1 (January 1996): 41–51. 
  40. a b  Daneault, Audrey, Véronique Coxam, and Yohann Wittrant. Biological Effect of Hydrolyzed Collagen on Bone Metabolism Critical Reviews in Food Science and Nutrition , May 2015, 00–00. 
  41.  ^  Liu, JunLi, Bing Zhang, ShuJun Song, Ming Ma, ShaoYan Si, YiHu Wang, BingXin Xu, Kai Feng, JiGong Wu, and YanChuan Guo. Bovine Collagen Peptides Compounds Promote the Proliferation and Differentiation of MC3T3-E1 Pre-Osteoblasts PLoS ONE Edited by Effie C. Tsilibary. 9, no. 6 (June 2014): e99920. 
  42.  ^  Wauquier, Fabien, Audrey Daneault, Henri Granel, Janne Prawitt, Véronique Fabien Soulé, Juliette Berger, Bruno Pereira, et al. Human Enriched Serum Following Hydrolysed Collagen Absorption Modulates Bone Cell Activity: from Bedside to Bench and Vice Versa Nutrients 11, no. 6 (May 2019): 1249. 
  43.  ^  König, Daniel, Steffen Oesser, Stephan Scharla, Denise Zdzieblik, and Albert Gollhofer. Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women A Randomized Controlled Study Nutrients 10, no. 1 (January 2018): 97. 
  44. a b  Elam, Marcus L., Sarah A. Johnson, Shirin Hooshmand, Rafaela G. Feresin, Mark E. Payton, Jennifer Gu, and Bahram H. Arjmandi. A Calcium-Collagen Chelate Dietary Supplement Attenuates Bone Loss in Postmenopausal Women with Osteopenia: A Randomized Controlled Trial Journal of Medicinal Food 18, no. 3 (March 2015): 324–31. 
  45.  ^  Cúneo, Florencia, Lúcia Costa-Paiva, Aarão Mendes Pinto-Neto, Sirlei Siani Morais, and Jaime Amaya-Farfan. Effect of dietary supplementation with collagen hydrolysates on bone metabolism of postmenopausal women with low mineral density Maturitas 65, no. 3 (March 2010): 253–57. 
  46.  ^  Vannucci, Letizia, Caterina Fossi, Sara Quattrini, Leonardo Guasti, Barbara Pampaloni, Giorgio Gronchi, Francesca Giusti, et al. Calcium Intake in Bone Health: A Focus on Calcium-Rich Mineral Waters Nutrients 10, no. 12 (December 2018): 1930. 
  47.  ^  Shapses, Sue A., L. Claudia Pop, and Yang Wang. Obesity is a concern for bone health with aging Nutrition Research 39 (March 2017): 1–13. 
  48.  ^  Zdzieblik, Denise, Steffen Oesser, Albert Gollhofer, and Daniel König. Improvement of activity-related knee joint discomfort following supplementation of specific collagen peptides Applied Physiology, Nutrition, and Metabolism 42, no. 6 (June 2017): 588–95. 
  49. a b  Clark, Kristine L., Wayne Sebastianelli, Klaus R. Flechsenhar, Douglas F. Aukermann, Felix Meza, Roberta L. Millard, John R. Deitch, Paul S. Sherbondy, and Ann Albert. 24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain Current Medical Research and Opinion 24, no. 5 (April 2008): 1485–96.×291967. 
  50.  ^  Zheng, Yan, Sylvia H. Ley, and Frank B. Hu. Global aetiology and epidemiology of type 2 diabetes mellitus and its complications Nature Reviews Endocrinology 14, no. 2 (December 2017): 88–98. 
  51.  ^  Dzau, Victor J. Mechanism of Action of Angiotensin-Converting Enzyme (ACE) Inhibitors in Hypertension and Heart Failure Drugs 39, no. Supplement 2 (1990): 11–16. 
  52.  ^  U.G., Yathisha, Ishani Bhat, Iddya Karunasagar, and Mamatha B.S. Antihypertensive activity of fish protein hydrolysates and its peptides Critical Reviews in Food Science and Nutrition 59, no. 15 (April 2018): 2363–74. 
  53.  ^  Kim, Se-Kwon, Dai-Hung Ngo, and Thanh-Sang Vo. Marine Fish-Derived Bioactive Peptides as Potential Antihypertensive Agents Marine Medicinal Foods – Implications and Applications – Animals and Microbes In , 249–60. Elsevier, 2012. 
  54.  ^  He, Hai-Lun, Dan Liu, and Chang-Bei Ma. Review on the Angiotensin-I-Converting Enzyme (ACE) Inhibitor Peptides from Marine Proteins Applied Biochemistry and Biotechnology 169, no. 3 (December 2012): 738–49. 
  55.  ^  Pujiastuti, Dwi Yuli, Muhamad Nur Ghoyatul Amin, Mochammad Amin Alamsjah, and Jue-Liang Hsu. Marine Organisms as Potential Sources of Bioactive Peptides that Inhibit the Activity of Angiotensin I-Converting Enzyme: A Review Molecules 24, no. 14 (July 2019): 2541. 
  56.  ^  Faria, Mariza, Elizabete Lourenço da Costa, José Antônio Rocha Gontijo, and Flávia Maria Netto. Evaluation of the Hypotensive Potential of Bovine and Porcine Collagen Hydrolysates Journal of Medicinal Food 11, no. 3 (September 2008): 560–67. 
  57.  ^  Saiga, Ai, Koji Iwai, Toru Hayakawa, Yoshihisa Takahata, Shiniich Kitamura, Toshihide Nishimura, and Fumiki Morimatsu. Angiotensin I-Converting Enzyme-Inhibitory Peptides Obtained from Chicken Collagen Hydrolysate Journal of Agricultural and Food Chemistry 56, no. 20 (October 2008): 9586–91. 
  58.  ^  Terashima, Masaaki, Mana Oe, Karin Ogura, and Saki Matsumura. Inhibition Strength of Short Peptides Derived from an ACE Inhibitory Peptide Journal of Agricultural and Food Chemistry 59, no. 20 (October 2011): 11234–37. 
  59.  ^  Yu, Zhipeng, Yang Chen, Wenzhu Zhao, Fuping Zheng, Long Ding, and Jingbo Liu. Novel ACE inhibitory tripeptides from ovotransferrin using bioinformatics and peptidomics approaches Scientific Reports 9, no. 1 (November 2019). 
  60.  ^  Lima, Dênis Pires de. Synthesis of angiotensin-converting enzyme (ACE) inhibitors: an important class of antihypertensive drugs Química Nova 22, no. 3 (June 1999). 
  61.  ^  Zhu, CuiFeng, Wei Zhang, Bo Mu, Fan Zhang, NanNan Lai, JianXin Zhou, AiMin Xu, JianGuo Liu, and Yong Li. Effects of marine collagen peptides on glucose metabolism and insulin resistance in type 2 diabetic rats Journal of Food Science and Technology 54, no. 8 (June 2017): 2260–69. 
  62.  ^  Zhu, Cuifeng, Wei Zhang, Jianguo Liu, Bo Mu, Fan Zhang, Nannan Lai, Jianxin Zhou, Aimin Xu, and Yong Li. Marine collagen peptides reduce endothelial cell injury in diabetic rats by inhibiting apoptosis and the expression of coupling factor 6 and microparticles Molecular Medicine Reports 16, no. 4 (July 2017): 3947–57. 
  63. Zhu, Cui-Feng, Guan-Zhi Li, Hong-Bin Peng, Yong Li, Fan Zhang, and Yun Chen. Therapeutic Effects of Marine Collagen Peptides on Chinese Patients With Type 2 Diabetes Mellitus and Primary Hypertension The American Journal of the Medical Sciences 340, no. 5 (November 2010): 360–66. 
  64.  ^  Zhu, Cui-Feng, Guan-Zhi Li, Hong-Bin Peng, Fan Zhang, Yun Chen, and Yong Li. Treatment with marine collagen peptides modulates glucose and lipid metabolism in Chinese patients with type 2 diabetes mellitus Applied Physiology, Nutrition, and Metabolism 35, no. 6 (December 2010): 797–804. 
  65.  ZHU, Cui-Feng, Guan-Zhi LI, Hong-Bin PENG, Fan ZHANG, Yun CHEN, and Yong LI. Effect of Marine Collagen Peptides on Markers of Metabolic Nuclear Receptors in Type 2 Diabetic Patients with/without Hypertension Biomedical and Environmental Sciences 23, no. 2 (April 2010): 113–20. 
  66.  Iba, Yoshinori, Koji Yokoi, Itsuka Eitoku, Masaki Goto, Seiko Koizumi, Fumihito Sugihara, Hiroshi Oyama, and Tadashi Yoshimoto. Oral Administration of Collagen Hydrolysates Improves Glucose Tolerance in Normal Mice Through GLP-1-Dependent and GLP-1-Independent Mechanisms Journal of Medicinal Food 19, no. 9 (September 2016): 836–43. 
  67.  Sayeed, Mohd, Sudeep Gautam, Devesh Pratap Verma, Tayyaba Afshan, Tripti Kumari, Arvind Kumar Srivastava, and Jimut Kanti Ghosh. A collagen domain derived short adiponectin peptide activates APPL1 and AMPK signaling pathways and improves glucose and fatty acid metabolisms Journal of Biological Chemistry 293, no. 35 (July 2018): 13509–23. 
  68.  Hsieh, C. H., T. Y. Wang, C. C. Hung, M. C. Chen, and K. C. Hsu. Improvement of glycemic control in streptozotocin-induced diabetic rats by Atlantic salmon skin gelatin hydrolysate as the dipeptidyl-peptidase IV inhibitor Food & Function 6, no. 6 (2015): 1887–92. 

Additional Collagen Studies

Fratzl P, editor. Collagen Structure and Mechanics. New York: Springer; 2008. 

Chung JH, Seo JY, Choi HR, Lee MK, Youn CS, Rhie G, Cho KH, Kim KH, Park KC, Eun HC. Modulation of skin collagen metabolism in aged and photoaged human skin in vivo. J Invest Dermatol. 2001 Nov;117(5):1218-24. 

Yazaki M, Ito Y, Yamada M, Goulas S, Teramoto S, Nakaya MA, Ohno S, Yamaguchi K. Oral Ingestion of collagen hydrolysate leads to the transportation of highly concentrated Gly-Pro-Hyp and its hydrolyzed form of Pro-Hyp into the bloodstream and skin. J Agric Food Chem. 2017 Mar 22;65(11):2315-2322. doi:10.1021/acs.jafc.6b05679. 

Stephens TJ, Sigler ML, Hino PD et al. A Randomized, Double-blind, Placebo-controlled Clinical Trial Evaluating an Oral Anti-aging Skin Care Supplement for Treating Photodamaged Skin. J Clin Aesthet Dermatol. 2016 Apr;9(4):25-32.  

Genovese L, Corbo A, Sibilla S. An Insight into the Changes in Skin Texture and Properties following Dietary Intervention with a Nutricosmeceutical Containing a Blend of Collagen Bioactive Peptides and Antioxidants. Skin Pharmacol Physiol. 2017;30(3):146-158.  

Pei XR, Yang RY, Zhang ZF et al. [Effects of marine collagen peptide on delaying the skin aging]. Zhonghua Yu Fang Yi Xue Za Zhi. 2008 Apr;42(4):235-8. Chinese. Kim DU, Chung HC, Choi J, Sakai Y, Lee BY. Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study. Nutrients. 2018 Jun 26;10(7):826.  

Asserin J, Lati E, Shioya T et al. The effect of oral collagen peptide supplementation on skin moisture and the dermal collagen network: evidence from an ex vivo model and randomized, placebo-controlled clinical trials. J Cosmet Dermatol. 2015 Dec;14(4):291-301.  

Choi SY, Ko EJ, Lee YH et al. Effects of collagen tripeptide supplement on skin properties: a prospective, randomized, controlled study. J Cosmet Laser Ther. 2014 Jun;16(3):132-7  

Yagoda M, Gans E. A nutritional supplement formulated with peptides, lipids, collagen and hyaluronic acid optimizes key aspects of physical appearance in nails, hair and skin. J Nutr Food Sci. 2014;S5:002.  

De Luca C, Mikhal’chik EV, Suprun MV et al. Skin Antiageing and Systemic Redox Effects of Supplementation with Marine Collagen Peptides and Plant-Derived Antioxidants: A Single-Blind Case-Control Clinical Study. Oxid Med Cell Longev. 2016;2016:4389410.  

Bhowmik D, Chiranjib KP, Sampath K. A potential medicinal importance of zinc in human health and chronic disease. Intl. J. Pharm Biomed Sci. 2010;1(1):5-11. 

Pullar JM, Carr AC, Vissers MCM. The Roles of Vitamin C in Skin Health. Nutrients. 2017 Aug 12;9(8):866 

Aloe Vera Studies

Miyuki Tanaka, Yuki Yamamoto, Eriko Misawa, Kazumi Nabeshima, Marie Saito, Koji Yamauchi, Fumiaki Abe, Fukumi Furukawa Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score: A 12-Week Double-Blind, Randomized, Controlled Trial Skin Pharmacol Physiol, 2016;29(6):309-317. doi: 10.1159/000454718. Epub 2017 Jan 14.

Informal articles about collagen

WebMD: Collagen: ‘Fountain of Youth’ or Edible Hoax?