“Of natural origin”: what ISO 16128 really says
By Jeremy Fain, founder of Restelys. Updated 17 October 2026. 2 sources cited.
“Natural” has no legal definition. An international standard nevertheless makes it possible to calculate precisely how natural a formula is.
ISO 16128 defines what a natural, naturally derived or non-natural ingredient is, then how to calculate the natural index of a finished product, water included.
It does not say one ingredient is better than another; it allows an honest comparison. That is why a percentage stated under ISO 16128 is worth far more than a simple “natural” on a bottle.
Each Restelys care product will display its index calculated under this standard, and our specification aims for the highest level that safe preservation allows.
Sources
- ISO 16128-1:2016, technical definitions and criteria for natural and organic ingredients.
- ISO 16128-2:2017, criteria for ingredients and products.
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