Anti-inflammatory effects of orally ingested collagen hydrolysate or glycine

Purpose: Collagen hydrolysate (CH) has been indicated to improve joint comfort and function. It is suggested that the specific amino acids derived from the collagen could reduce pain and help to protect the joint in osteoarthritis (OA) patients. Glycine comprises about one third of the amino acids in the collagen. It has been shown that the free glycine levels in the blood increase after ingestion of CH. Furthermore, preclinical studies indicate an anti-inflammatory effectiveness of glycine. The present study evaluates the anti-inflammatory capacity of CH and glycine. Methods: Different amounts of CH (12.5, 25 and 50 mg/mouse) and glycine (10, 20 and 50 mg/mouse) were administered orally to Balb/C mice, aged 14 weeks. Inflammation was induced, 3 h after administration of the test components, by injecting zymosan (25 μl, 0.5% in PBS) intradermally in the ear. Ear-swelling, as a measure for inflammatory response, was detected using an engineer's micrometer. Serum levels of glycine and LPS stimulated production of IL-6 and TNF-α in whole blood or PBMC were detected at 3 h after intake of the test components. Results: Both CH and glycine were able to counteract the zymosan-induced ear swelling at 3 h after zymosan injection in a concentration depending manner. This effect was accompanied by a concentration dependent increase in the levels of free serum glycine and a decrease in the production of pro-inflammatory cy-tokines. The CH effects were less pronounced compared to the glycine effects. Conclusions: The present study indicates that CH is able to display an anti-inflammatory activity. The reduction of pain by CH, as indicated in several clinical studies in patients with OA, could at least partially origin from the anti-inflammatory capacity of CH.