Gluconolactone
Gluconolactone · INCI Gluconolactone
Every product with water in it has to be preserved. Gluconolactone is part of how ours is, working with sodium benzoate at the pH sodium citrate holds. It is also a polyhydroxy acid, and that has led to some confusion worth clearing up.
It is part of our preservative, with sodium benzoate. It is also a PHA, and at the level we use, its job in the bottle is preserving.
What it is
Gluconolactone is made by fermenting glucose. In water it slowly converts to gluconic acid. It is gentle, well tolerated, and accepted under the organic cosmetic standards, which is why we chose it.
Two things keep each bottle sound. The first is the preservative, a ready-made blend of sodium benzoate and gluconolactone. Sodium benzoate does the preserving, and gluconolactone helps it work. The second is the pH. Sodium citrate buffers the cream at pH 5 to 5.5, close to the skin's own. At the end of making, the pH is checked and fine-tuned with a little sodium hydroxide or citric acid.
Gluconolactone has several hydroxyl groups that hold water, so it acts as a light humectant as well as part of the preservative. It also binds trace metals in the cream, which helps keep the formula stable. At much higher strengths it is studied as a gentle exfoliant; at the level we use, it does not exfoliate.
What it does in our formulas
Gluconolactone is part of the preservative in every formula. It also holds a little water and binds trace metals.
It helps preserve the product
Sodium benzoate does the preserving, and gluconolactone helps it work. In water, gluconolactone slowly converts to gluconic acid. Sodium citrate buffers the cream at pH 5 to 5.5, where the pair works. Any product containing water needs preserving, ours included.
Well characterisedIt holds water
Gluconolactone has several hydroxyl groups that hold water, so it acts as a light humectant as well as part of the preservative.
Well characterisedIt binds trace metals
Gluconolactone binds trace metals in the cream, which helps keep the formula stable.
Well characterisedWhat the research does not show
Two claims made around gluconolactone need correcting.
Marketed as A PHA that resurfaces and exfoliates your skin
Marketed as Preservative-free, or self-preserving
On the label and in the range
Gluconolactone appears in every one of our formulations, in the middle of the ingredient list, with sodium benzoate further down. The two make up the preservative, so read them as a pair. The exact percentage is published on each product page.
Is it suitable for me?
Gluconolactone is well tolerated on sensitive skin. It suits a vegan routine, is accepted under the organic cosmetic standards, and carries no restrictions under UK or EU cosmetic law.
As with anything new, if your skin reacts easily it is worth patch testing first.
The research behind this page
We review the published literature. We do not conduct the studies below.