I first learned about this product while reading Flawless: Lessons in Looks and Culture from the K-Beauty Capital by the National Public Radio (NPR) reporter Elise Hu. She mentioned the use of a product derived from salmon gonads (seriously) that South Koreans inject in their face at cosmetic clinics, ostensibly for the purposes of improving the appearance of the skin. Additional research revealed that this product, called Rejuran®, is available not only in South Korea but also now in Europe and Australia. It is an injectable like hyaluronic acid fillers but rather than using cross-linked hyaluronic acid to add volume to the face, fish gonadal polynucleotides are injected to increase the production of collagen and elastin in the skin, both of which are important to maintain the smooth and supple qualities of youthful skin.

Polynucleotides are simply a string of signaling molecules which DNA and RNA is composed of. I am skeptical that a chain of these molecules from fish can somehow induce signaling in another species (i.e., humans) to achieve cosmetic results. Interestingly, the only study I found in the literature on this product was a phase III trial of Rejuran® conducted in South Korea in 2014 that was retracted from the medical literature two years after its publication (1). That, to me, is a red flag regarding its actual safety and effectiveness. Additional studies should help determine whether this product is worth evaluation by the FDA.