sodium ascorbyl phosphate
Sodium Ascorbyl Phosphate at a Glance
- Stable, water-soluble derivative of ascorbic acid (vitamin C)
- Helps reduce signs of ageing and hyperpigmentation
- Enzymes in skin convert this ingredient to pure vitamin C
- Doesn’t require a low pH range to be effective
- Works well with other forms of vitamin C and vitamin E
Sodium Ascorbyl Phosphate Description
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, packaging 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).
Sodium Ascorbyl Phosphate References
Journal of Cosmetic Dermatology, January 2021, pages 174–180
Pharmaceutics, December 2018, ePublication
Annals of Dermatology, August 2015, pages 376–382
Chemical Society of Pakistan, March 2013, pages 1,096–1,102
International Journal of Cosmetic Science, June 2005, pages 171-176
International Journal of Toxicology, Supplement 2, March 2005, pages 51–111
International Journal of Pharmaceutics, April 2003, pages 65–73
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Paula Begoun is the best-selling author of 20 books about skincare and makeup. She is known worldwide as The Cosmetics Cop and creator of Paula’s Choice Skincare. Paula’s expertise has led to hundreds of appearances on national and international radio, print, and television including:
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