L-ascorbic acid is the most powerful type of vitamin C and can help brighten skin and prevent signs of aging. Here are the best L-ascorbic acid serums, according to derms and editors.

Why it's so great: It's oil-free, it uses a relatively low dose of L-ascorbic acid, and it includes hydrating powerhouse vitamin B5—plus, the formula is packed with ceramides and hyaluronic acid ...

The added ascorbic acid acts as a preservative, but it also has many health benefits. ... Recipe variations include using apple cider in place of water, squeezing in some lemon juice, ...

The most potent forms of vitamin C are often the most unstable, such as L-AA, or L-ascorbic acid, meaning that these serums are vulnerable to light, heat, and air.