Biotin is the B vitamin you've probably heard most about in the context of hair and nails. Walk past any pharmacy beauty aisle and you'll see biotin products pitched at hair growth, glossy nails, clearer skin. The reason isn't marketing alone. It's that biotin is a cofactor for the enzymes your body uses to actually build keratin (the protein in hair and nails) and to metabolise the amino acids that go into skin tissue.
Frank biotin deficiency is rare in healthy adults but mild shortfalls are more common than people realise, particularly during pregnancy, in people who eat a lot of raw egg whites (which contain a biotin binder), or in those on long term anticonvulsant medication. The classic signs are brittle nails, thinning hair, dry or scaly skin, and tiredness.
The interesting thing about biotin is how it pairs with collagen. Collagen gives your body the structural protein, but biotin gives it the cofactor it needs to actually build keratin and synthesise the fatty acids that keep skin healthy. Take one without the other and you're only doing half the job. This is why Daily Greens+ and Marine Collagen split the biotin dose across the two gummies in your daily mini pouch, totalling 200% NRV.