Vasoprotective Effect of Foods as Treatments: Chicken Collagen Hydrolysate

Collagen is a major protein in living organisms and accounts for about one-third of all protein in mammalian bodies, including the human body. Recently, collagen peptides have been used as foods that take advantage of their tertiary functions. We have been focusing on the vasoprotective effect of collagen peptides. Chicken collagen hydrolysate (CCH) is obtained by treating chicken feet with enzymes to produce an angiotensin-converting enzyme (ACE) inhibitory peptide. Administration of this CCH for 12 weeks reduces blood pressure in humans. We therefore investigated the mechanism of the vasoprotective effect of CCH. We tested whether prolonged CCH treatment of rats or mice would restore endothelial cell function and improve proinflammatory cytokine levels. We found that CCH treatment improved the vasorelaxation of rat aorta damaged with L-NG-nitroarginine methyl ester , an NO synthesis inhibitor. CCH treatment also reduced the serum levels of IL-6, sICAM-1, and TNF-α in an atherosclerotic mouse model, C57BL/6.KOR-ApoEsh1. These findings indicate the usefulness of collagen peptides as foods promoting antiatherogenesis via a vasoprotective effect. Years have passed since functional foods and their tertiary function first attracted attention. The primary function of foods is to supply the nutrients required to sustain life, and the secondary function is to satisfy taste preferences. The tertiary function of foods is to exert biological regulatory effects, such as biophylaxis, homeostatic maintenance, and disease prevention, which are activated upon food intake. Purified food ingredients that have tertiary functions are widely consumed as supplements. Multitudes of supplements are available on today’s market: besides common vitamins, minerals, and amino acids, there are catechins, which are antioxidant constituents of tea (Katiyar, 2003), soy isoflavones, which have female hormone–like actions (Weijer, 2002), and docosahexaenoic acids and eicosapentaenoic acids, which decrease triglyceride levels (Tamai, 2004). Collagen is being used widely, not only in supplements but also as an ingredient of common food products such as beverages, yogurts, and breads. Collagen is a major protein in living organisms and accounts for about one-third of all protein in mammalian bodies, including the human body. It forms an extracellular matrix that plays a role in the formation of connective tissues and acts as a scaffold for cells, but its accumulation declines with age. The majority of the collagen in the body exhibits a triple