Gluconolactone
Gluconolactone · INCI Gluconolactone
Every product with water in it has to be preserved, and most brands would rather not talk about how. This is our preservative. It is also, as it happens, a polyhydroxy acid, and that has led to some confusion we would like to clear up, including in our own earlier copy.
It is our preservative. It is also a PHA, and we are going to be straight about which of those two things it is actually doing in your jar.
What it is
Gluconolactone is made by fermenting glucose. In our formulas it works alongside the sodium benzoate further down the ingredient list: together they slowly release gluconic acid, and that keeps the product free of bacteria and mould for its life on your shelf. It is a gentle system, well tolerated, and accepted under the organic cosmetic standards, which is why we chose it over the harsher options.
It has a useful second property. Gluconolactone carries several hydroxyl groups, and each one attracts water, so it works as a humectant at the same time. Most preservatives do nothing for your skin. This one holds a little water in it, which is a genuine bonus rather than a claim we have stretched.
Now the part that needs care. Gluconolactone belongs to the polyhydroxy acid family, the PHAs, and PHAs are well known as gentle exfoliants. That is true, at the levels exfoliating products use, which are several times ours. We use it at just over one percent, to preserve. At that level it is not resurfacing your skin, and we would rather tell you that than let three flattering letters do work they have not earned.
What it does in our formulas
Two things, and the first is the one nobody puts on a front label.
It keeps the product safe
This is its main job. Gluconolactone works with the sodium benzoate further down the list, slowly releasing gluconic acid, and together they protect the formula from bacteria and mould. Any product containing water needs preserving. Ours needs it too, and this is how.
Well characterisedIt holds water
A genuine second benefit rather than a marketing one. Gluconolactone carries several hydroxyl groups, and each attracts water, so it acts as a humectant while it does its preserving. It is one of the few preservative systems that gives something back.
Well characterisedWhat the research does not show
One of these corrections is aimed at us, which is a first for these pages, and it is the more important of the two.
Marketed as A PHA that resurfaces and exfoliates your skin
Marketed as Preservative-free, or self-preserving
So: a gentle, fermentation-derived preservative that also holds a little water. That is a good, honest thing for an ingredient to be, and it is what this one is.
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 work together, and it is worth reading them as a pair rather than as separate ingredients. The exact percentage is published on each product page, as it is for everything we use, including the parts most brands would rather you did not think about.
Is it suitable for me?
Gluconolactone is among the gentlest preservative options available, well tolerated on sensitive skin, and the research shows polyhydroxy acids in general are compatible with reactive and rosacea-prone 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.