Ester-C description

Trade name for a combination form of vitamin C that contains mainly calcium ascorbate, but in addition contains small amounts of the vitamin C metabolites dehydroascorbic acid (oxidised ascorbic acid), calcium threonate, and trace levels of xylonate and lyxonate. The manufacturer of this ingredient states that the metabolites, especially threonate, increase the effectiveness of the vitamin C in the product. However, this study has not been published in a peer-reviewed journal. There is a small, in vitro study that supports the notion that Ester-C is more potent than ascorbic acid by itself.

Ester-C references

  • Medical Science Monitor, October 2007, pages 205-210

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated

We have not yet rated this ingredient because we have not had a chance to review the research on it.