Glycine

If your skin had a favourite tiny helper, glycine would be a very plausible candidate. It’s the smallest amino acid, but it punches above its weight: glycine is one of the building blocks of collagen, the protein that gives skin its structure and bounce, and it also shows up in many skin peptides. In skincare formulas, its most straightforward job is often as a moisturising and skin-conditioning ingredient, helping products feel gentler and more cushiony on the skin.

There’s also some interesting geekiness around glycine and skin barrier support. Amino acids are part of the skin’s natural moisturising system, and glycine can help formulas mimic that “natural hydration” vibe. It doesn’t have the celebrity status of niacinamide or hyaluronic acid, but it’s the sort of ingredient that quietly does useful work. In lab settings, glycine-containing peptide combinations have been studied for supporting wound repair and improving the look of aging skin, although on its own in a facial product, it’s more of a supporting actor than a miracle worker. Still, if you’re into fragrance-free, barrier-friendly formulas, glycine is a nice little bonus.

Now for the elephant in the search bar: most of the internet chatter about glycine is actually about supplements, especially glycine before bed and glycine for sleep. Small human studies suggest 3 grams taken before bedtime may help people feel less tired the next day and may improve subjective sleep quality, likely by nudging body temperature and sleep physiology in a favourable direction. That’s a supplement topic, not a skincare one, but it explains why people hunt for the best glycine powder, the best glycine supplement for sleep, or glycine powder supplement brands in places like the UK, Australia, Holland and Barrett, Kruidvat, or “kopen” searches. People also look up glycine and NAC because the two are often paired in antioxidant discussions, and glycine has been studied in metabolic and recovery contexts too.

As for benefits of glycine for men or women, the answer is mostly the same: it’s a simple amino acid with roles in protein synthesis, antioxidant systems, and sleep support when taken orally. There’s also interest in glycine with tirzepatide, but that’s a medical rabbit hole and not a skincare claim. For your face, glycine is best understood as a gentle, skin-friendly amino acid that can help a formula feel more comfortable and supportive — not glamorous, but definitely the kind of ingredient your skin doesn’t mind having around.

A non-essential amino acid (the building blocks of skin proteins, like collagen or elastin), that the body can produce itself, but its production decreases with age. When you put it all over your face, it works as a moisturizerand maybe more. 

According to great skincare blog Futurederm, glycine might help with wound healing and tissue repair and when used together with other amino acids, leucine and proline it might improve wrinkles. 

BTW, it's also a building block of a bunch of important and famous peptides, including copper-tripeptide-1, palmitoyl tripeptide-1 or palmitoyl hexapeptide-12.