Macadamia Ternifolia Seed Oil Phytosterol Esters — INCI reference

What it is

Macadamia Ternifolia Seed Oil Phytosterol Esters is an ester formed by combining phytosterols (typically derived from soy) with the fatty acids of macadamia nut oil, which are predominantly palmitoleic and oleic acids. It appears as a white paste at room temperature with a melting point near 45°C, allowing it to spread easily on skin. The ingredient acts as a botanical substitute for cholesteryl esters naturally present in the skin's surface lipid layer, integrating into the stratum corneum to help restore barrier function. It reduces transepidermal water loss, softens skin without a greasy afterfeel, and provides a dry-touch, velvety finish suitable for fluid emulsions, lightweight serums, and dry-touch body oils. In hair care it improves manageability, softness, and shine. It is also used as a lanolin substitute due to its water-absorption capacity.

Safety & warnings

Generally regarded as low irritation risk. Refined phytosterol esters contain minimal protein residues, reducing allergy potential, but individuals with macadamia nut or tree nut sensitivities should patch test. Not formally evaluated for comedogenicity; rated 2 out of 5 (low to moderate) in informal assessments, so use with caution on acne-prone skin. No known regulatory restrictions in the EU, US, or JP markets. The Cosmetic Ingredient Review (CIR) Expert Panel has assessed phytosterols and phytosterol esters as a class and deemed them safe for cosmetic use.

Origin & sourcing

Derived from two natural plant sources: macadamia nut oil (cold-pressed or refined from the seeds of Macadamia ternifolia/integrifolia, native to Australia) and phytosterols typically extracted from soybean oil (non-GMO). The two components are combined through solvent-free esterification under heat and vacuum. The commercial origin is noted as the USA. Natural origin index is 1 per ISO 16128, and it is vegan, palm oil-free, and cruelty-free.

History

Phytosterols were recognized as skin-related lipids in the 1950s when researchers observed their structural similarity to skin cholesterol. The specific esterification of soy phytosterols with macadamia oil fatty acids was developed as part of the biomimetic skincare movement, gaining broader use in the 2010s especially in Korean cosmetic formulations. The ingredient appears in the EU CosIng database and INCI nomenclature system. CAS 227200-30-8 is associated with the closely related INCI name Phytosteryl Macadamiate.

Questions everyone asks

What is the difference between Macadamia Ternifolia Seed Oil Phytosterol Esters and Phytosteryl Macadamiate?

These are two INCI names for functionally the same ingredient class: an ester of phytosterols and macadamia oil fatty acids. Phytosteryl Macadamiate (CAS 227200-30-8) denotes the ester from the phytosterol side, while Macadamia Ternifolia Seed Oil Phytosterol Esters names it from the oil side.

How does this ingredient benefit the skin barrier?

It mimics cholesteryl esters, one of the key lipid components of the stratum corneum. By replenishing these skin-identical lipids, it helps seal the barrier, reduce transepidermal water loss, and support healthy skin hydration without a heavy or greasy feel.

Is this ingredient suitable for sensitive or dry skin?

Yes, it is considered suitable for dry, normal, and sensitive skin types due to its low irritation profile and biomimetic barrier-repairing properties. Those with oily or acne-prone skin should use it with some caution given a low-to-moderate comedogenic rating.

Can it replace lanolin in formulations?

It is used as a lanolin substitute in some formulations due to its capacity to absorb water and its ability to soften and protect skin. Unlike lanolin it is entirely plant-derived, vegan, and free of animal-sensitizing proteins.