Hyaluronic acid acts as a humectant, which means it holds water. “HA is a chain of carbohydrates that can hold up to 1000 times its weight in water,” says David Kim, MD, MS, board-certified dermatologist. “It’s an ingredient that helps your skin look hydrated and plump.”
There’s not just one form of hyaluronic acid – it comes in a variety of sizes that have the ability to penetrate different layers of the skin. “Each molecule is assigned a molecular weight, which is inversely related to the depth to which it is found,” says Rina Allawh, MD, board-certified dermatologist at Schweiger Dermatology Group in King of Prussia, PA. molecules can penetrate the skin. The smaller the molecule, the deeper its ability to penetrate the skin.
It seems like you always want to use the lowest molecular weight hyaluronic acid possible, but that’s not always the case. “The advantage of a higher molecular weight hyaluronic acid serum is its anti-inflammatory and soothing properties, as it forms a durable film with the top layer of the skin,” says Allawh. “Low molecular weight hyaluronic acid serums are more likely to have long-lasting regenerative and anti-wrinkle effects and work in the deeper layers of the skin. As you can imagine, hyaluronic acid serums have weight. Lower molecules can lock moisture in the skin’s connective tissues and as a result stimulate a firming effect.”
