Sodium Ascorbyl Phosphate

Sodium ascorbyl phosphate (SAP, for short) is a stable, water-soluble form of vitamin C made from combining ascorbic acid with a phosphate and a salt, compounds which work with enzymes in skin to cleave (split) the ingredient and release pure ascorbic acid, which is the most researched form of vitamin C.

Just like pure vitamin C, sodium ascorbyl phosphate functions as an antioxidant on and within skin. When used in higher amounts, it can be effective for brightening a dull skin tone, smoothing wrinkles, visibly firming skin, and reducing discolourations.

The usual concentration of sodium ascorbyl phosphate in skin care ranges from 0.2-3%, an effective range to help improve skin’s environmental defenses and target lines and wrinkles, especially when paired with oil-soluble vitamin E for antioxidant synergy that improves the stability of both ingredients.

A 5% concentration of sodium ascorbyl phosphate was shown in a comparative study with the same amount of ascorbic acid to have equivalent wrinkle-smoothing and elasticity-increasing benefit to skin around the eyes.

Amounts above 3% are considered necessary to target discolourations, similar to the range research has shown ascorbic acid works within to target this concern.

There is also research showing amounts of 1% and 5% concentrations of sodium ascorbyl phosphate can influence factors linked to breakouts, likely due to its skin soothing effect. Thus, this form of vitamin C may be an effective adjunct to anti-acne products that contain benzoyl peroxide and salicylic acid.

Along with other forms of vitamin C, it is considered safe as used in skin care products. This versatile form of vitamin C works in both water- and oil-based formulas without breaking down, but despite this impressive stability, packageing is still important. This is because such stability isn’t impenetrable, meaning ongoing exposure to light and air can still weaken its efficacy, although certainly not as quickly as occurs with pure vitamin C (ascorbic acid).