Phytosteryl Macadamiate
No meaningful concern for most people; irritation is possible but rare.
Also written as: Macadamia Ternifolia Seed Oil Phytosterol Esters
What it is
This is a designed lipid: plant sterols (phytosterols) esterified with the fatty acids of macadamia oil. Sterol esters are a genuine component of human skin surface lipids and of the intercellular lipid mixture, so the ingredient is intended to slot into that structure rather than just sit on top. It is used in barrier-focused moisturisers and in products aimed at dry, mature skin.
What it does well
Sterol-ester structure similar to skin's own surface lipids
Sterol esters occur naturally in the stratum corneum lipid mixture, and this ingredient is built to resemble them. Direct clinical evidence for this specific ester is scarce; the rationale rests on barrier lipid biology rather than on trials of the ingredient itself.
Limited evidence
Worth knowing
Macadamia-derived
The fatty acid portion comes from macadamia nuts, a declarable food allergen in the EU. As with macadamia oil itself, the ester is a highly processed lipid with negligible protein content and reactions are not an established problem.
Matters most toPeople with a diagnosed macadamia or tree-nut allergy.
Where the EU stands
No specific restriction
Not listed in any Annex of the EU Cosmetics Regulation, so there is no specific concentration limit; it is still covered by the general safety assessment every cosmetic product must pass before sale.
