Significant Discrepancies in "Functional Characterization of Undenatured Type II Collagen Supplements: Are They Interchangeable?": A Rejoinder.

In 2021, an article was published comparing two commercial products containing undenatured type II collagen: b-2Cool® (Bioiberica, S.A.U., Barcelona, Spain; designated CII-X, X1, and X2) and UC-II (Lonza Consumer Health Inc, USA; designated CII-Y, Y1, and Y2). However, we feel certain concerns remain where clarification may be warranted.