Type II collagen (undenatured) retains its native triple-helix structure and is not absorbed as structural material. It acts via immune modulation, helping regulate the inflammatory response in joints. Because of this mechanism, it is effective at low daily doses, typically 10–40 mg. Collagen peptides are collagen that has been hydrolyzed into low-molecular-weight peptides. These peptides supplying amino acids that serve as nutritional building blocks for joint cartilage. Due to this nutritional role, higher daily intakes are required, especially for joint support compared with skin support.

Sugar is commonly added to collagen drinks to mask fishy taste. FLEXPRO contains no added sugar. It uses mixed berries juice powder for flavor and sucralose (14.9 mg) as a non-caloric sweetener, which does not significantly affect blood glucose levels. As such, FLEXPRO is generally suitable for individuals managing diabetes, with standard advice to consult a healthcare professional.

There is no clinical evidence that collagen peptide intake causes or promotes cyst or fibroid growth. Collagen peptides are broken down into amino acids, similar to those obtained from normal dietary protein intake. However, individuals with a medical history of cysts or fibroids who have been advised by their healthcare professional to avoid collagen supplementation should follow medical advice.