“…2 Age and collagen-related food intake or nutritional support, 4 which can influence the rate and amount of collagen production, are also significant residual confounders that should be considered. 5 Likewise, effect measure modification by common comorbidities or risk factors for RA and OA of inflammatory or autoimmune conditions, 6,7 including psoriasis, 8,9 psoriatic arthritis, 10,11 spondyloarthritis, 12 irritable bowel syndrome, 13 periodontitis or other oral diseases, 7,14-21 fibromyalgia, 22 and obstructive sleep apnea, 23,24 may be elucidated to identify populations that may benefit from collagen supplementation.To better understand the safety and adverse effects of collagen supplementation, it is important to consider potential confounders, such as the concomitant use of medications. This would be essential in determining whether the observed toxicities were a result of collagen supplementation or co-medications.…”