Butyrospermum parkii (shea) butter is used in a variety of cosmetics and personal care products as an emollient that may offer anti-aging benefits.
Shea butter is a fat extracted from the nuts of the shea tree (Vitellaria paradoxa, formerly Butyrospermum parkii), which is native to Africa. The shea nuts are lightly boiled and then sun-dried prior to grinding into a paste. Lastly, the fat is extracted from the paste and turned into butter through churning. It is usually yellow in color when raw, however, more processed versions can be ivory or white in color. Shea butter contains the following fatty acids: oleic acid (40 to 60%), stearic acid (20 to 50%), linoleic acid (3 to 11%), palmitic acid (2 to 9%), and arachidic acid (less than 1%).
Shea butter is used in many different types of products, such as lip gloss, skin moisturizer creams and emulsions, bath products, suntan products, and hair conditioners. It can also be used to make soaps, however, it must be used in small amounts since it contains many nonsaponifiable components (substances that cannot be fully converted into soap by treatment with alkali).
In cosmetics and personal care products, shea butter primarily functions as an emollient, but it also possesses some anti-aging properties.
Shea butter is an emollient that works to soften and soothe the skin. Since shea butter melts at body temperature, it is able to coat the skin and form an occlusive film. This film helps to prevent evaporation of the skin’s natural moisture and increases skin hydration by causing buildup of water in the stratum corneum (the uppermost layer of skin).
In fact, shea butter has been shown to be superior to mineral oil at preventing transepidermal water loss (TEWL). One study tested this by washing participants’ arms in water containing ethanol, then examining how shea butter compared to mineral oil in terms of helping the skin recover. Within two hours, the researchers found that shea butter was able to help the skin totally recover from TEWL. After three to four hours, shea butter was found to improve the skin barrier. With the mineral oil, there was a slower recovery and starting values were not recovered.
Another study published in the Journal of Allergy and Clinical Immunology compared the effects of shea butter to Vaseline (petrolatum) for treating eczema. Using a scale from zero to five (zero denoting clear and five denoting very severe disease) shea butter took a three down to a one, while Vaseline only took a three down to a two. Thus, the study concluded that shea butter works as an effective emollient for eczema.
The rich supply of triglycerides and fatty acids in shea butter help to replenish the skin’s natural barrier function. The stratum corneum is composed of corneocytes (dead skin cells) held together by a lipid barrier. In addition to fatty acids, the barrier consists of ceramides and cholesterol. A deficiency in these essential lipids can lead to a weak or damaged barrier, which can subsequently allow harmful things like allergens, bacteria, and irritants to pass through the skin. This results in symptoms of dryness, itching, and irritation, and may lead to the development of skin conditions like acne, eczema, and even signs of aging. Using ingredients that replenish the skin’s barrier, such as shea butter, can help to prevent these problems.
In addition to its moisturizing properties, shea butter may also be able to improve the appearance of aging skin due to its nonsaponifiable components. A study published in the journal Phytotherapy Research determined that the nonsaponifiable fractions of avocado and soybean oils stimulate the synthesis of collagen and elastin fibers, which reverses the degenerative skin changes seen with aging. Thus, the nonsaponifiable components of shea butter may be able to stimulate collagen synthesis, leading to a more youthful complexion.
The safety of butyrospermum parkii (shea) butter has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated scientific data and concluded that this ingredient was safe for use in cosmetics and personal care products.
References: Wikipedia, “Shea Butter”, Better Shea Butter, “Shea Butter vs Cocoa Butter – What’s The Difference?”, 2014, Cosmetics Design Europe, “Moisturizing Power of Shea Butter Highlighted By Scientific Studies”, 2009, J Allergy Clin Immunol. 2009, 123(2)S41, Phytother. Res., 1993, 7: S53-S56, Cosmetics Info, “Butyrospermum Parkii (Shea) Butter”.