Magnesium ascorbyl phosphate (MAP) is a form of vitamin C that has been combined with a magnesium salt to make it more stable in water-based products. It is thought to be relatively resistant to light and air, but its potency may be reduced with frequent exposure to these elements. Unlike other water-soluble forms of vitamin C, MAP is also lipophilic, meaning it can penetrate the skin more effectively. This form of vitamin C is used in skin care products to help lighten the complexion, scavenge free radicals, and support collagen production. Although the extent to which it converts to ascorbic acid within the skin is still being studied, it has been shown to be able to hydrate the deeper layers of skin more effectively when compared to ascorbic acid.