Serine

If your skin could keep a little stash of its own moisture helpers, serine would definitely be on the list. This amino acid shows up naturally in the skin’s outer layer as part of the natural moisturizing factor, where it helps your skin hold on to water and stay comfortable. In formulas, you’ll usually find it in moisturizing blends rather than as a solo star, because its real superpower is supporting hydration rather than acting like a flashy active. That makes the overall function of serine pretty straightforward but useful: it helps skin feel softer, smoother, and less tight. Cute little workhorse, basically.

Serine is a non-essential amino acid, which means your body can make it on its own, and it can also be obtained from food. In nutrition-land, people often talk about the health benefits of serine, l-serine, and even d-serine, but those conversations are mostly about the brain and metabolism, not skincare. The same goes for phosphatidylserine, which is a phospholipid containing serine and is studied for cognitive support. Those supplement-related searches, like the best serine supplement or how to take l serine, are a different beast altogether. On the skin, what matters is that serine can help support hydration when used topically, especially alongside other humectants and barrier-friendly ingredients.

As for the “best sources of serine” in real life, food-wise it’s found in high-protein foods such as soy, eggs, fish, meat, nuts, and legumes, and if you’re hunting for foods highest in l-serine, protein-rich options generally win. In supplements, people may compare the best l serine supplement, best d serine supplement, or best phosphatidylserine depending on the goal, but again, that’s not really relevant to your moisturizer. Cosmetic serine is about skin feel, not prescription-style dosing, whether you’re wondering about the l serine best time to take or how to take phosphatidyl serine. Small side note: serine codons are part of genetics, not cosmetics, and “serine ayari” doesn’t have a known skincare meaning.

Bottom line: in skincare, serine is a gentle, sensible hydration helper rather than a miracle worker. It’s most useful when paired with other humectants and barrier-supporting ingredients, where it contributes to a more hydrated, less cranky skin surface. If you like formulas that make your skin feel plumper and more comfortable without drama, serine fits right in.

Serine is an amino acid that most often comes to the formula as part of a moisturizing complex. It's a non-essential amino acid (meaning that our body can synthesize it) and serves as a water-binding ingredient.

In general, amino acids are great skincare ingredients that play an important role in proper skin hydration but there is not much info out there about what specifically serine can do for the skin.