Glycine is generally a reasonable cosmetic ingredient for seborrheic-dermatitis-prone skin, but it is not a proven treatment. It is a small amino acid used for conditioning and buffering, and ordinary product suitability still depends on the full formula.

Laboratory studies show that one Malassezia species can use glycine as a nitrogen source in culture. That is worth recording, but it does not show that the amount of glycine in skincare feeds yeast on human skin or worsens seb derm, and the most common seb derm-associated species were not tested in a cosmetic setting. Treat this as a theoretical limitation, not a reason to reject every glycine-containing product.