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BACKGROUND: Renewed consumer and industry interest in natural ingredients has led to a large growth of natural cosmetics. This has put pressure on formulation skills and product claims when it comes to using natural compounds. Taking a strategic and comprehensive approach in viewing natural ingredients, including natural oils, as 'active' ingredients rather than just providing for so-called 'natural' claims, aids both innovation and development. Given the ever-increasing consumer demand for natural ingredients, and more importantly the demand for effective natural ingredients including plant oils, it is important for the cosmetic industry to re-evaluate them in this context. METHOD: The objectives of this review are to provide an update of three popular cosmetic plant oils - Sweet Almond, Evening Primrose and Jojoba - in terms of their cosmetic applications as 'active' ingredients. This review highlights the activity of these oils, in the management of dry skin, ageing skin, juvenile skin, atopic dermatitis, scalp conditions and their wider potential. Attention is given to formulation considerations where the content of these oils impacts product oxidation, skin penetration and stratum corneum homeostasis. RESULTS: Benefits of these oils have been well documented both pre-clinically and clinically. Historically, they have been used for hundreds if not thousands of years for their management and treatment of various skin and other ailments. Given the discrepancies in some clinical data presented for a variety of dermatoses, the importance of the choice of oil and how to formulate with them within the context of the epidermal barrier function, skin penetration and toxicity cannot be underestimated. Care should be taken in terms of the quality and stability of theses oils, as well as ensuring best formulation type, if the reported activities of these oils are to be achieved with consistency. Despite discrepancies in the literature and questionable study designs, it is clear that Sweet Almond, Evening Primrose and Jojoba oils do have skin care benefits for both adult and juvenile applications. CONCLUSION: They are effective ingredients for skin care preparations to strengthen stratum corneum integrity, recovery and lipid ratio. Nevertheless, further experimental data are required concerning the impact on stratum corneum physiology and structure.
Blaak et al. (Sun,) studied this question.