The fat of the nut of the African Shea tree (Vitellaria paradoxa) is the source of Shea butter. The traditional use of the butter is to reduce the appearance of fine lines, scars and stretch marks, and to ease a variety of skin irritations, such as psoriasis, eczema and sunburn. Makers of cosmetics also mix this natural substance with other botanical ingredients. Shea butter is ideal for the topical application of cosmetic and medicinal formulas, because it melts on contact and is readily absorbed into the skin, without leaving a greasy residue.
The healing qualities of Shea butter are due to the presence of several fatty acids and plant sterols, namely oleic, stearic, palmitic and linolenic acids. These oil-soluble components are nonsaponifiable, meaning they do not undergo saponification, or convert to soap, when introduced to an alkali. Shea butter possesses a significantly greater nonsaponifiable fraction than most other nut oils and fats, which lends the substance greater healing potential for the skin.
Shea butter contains several derivatives of cinnamic acid, a compound common to cinnamon and balsam trees. In the May 2010 issue of the "Journal of Oleo Science," Toshihiro Akihisa and fellow researchers published the results of a study that investigated the effects of four triterpene acids and four triterpene cinnamates isolated from Shea butter on tissue swelling in mouse skin. The scientists reported that Shea butter not only demonstrated anti-inflammatory benefits, but one compound, lupeol cinnamate, also prevented tumor development in a carcinogenesis test, a procedure in which cancer cells are literally "grown" in a culture dish.
Shea butter contains vitamins A and E, as well as catechins, plant antioxidants also found in green tea. While it is unclear how well vitamins A and E in raw Shea butter are absorbed, there is evidence to suggest that cinnamic acid esters in Shea fat help to prevent skin damage from ultraviolet radiation.
Shea butter softens and conditions leather and wood, so musicians use it to improve the flexibility of leather tuning straps, and the pitch and timbre of animal skin drums and other percussion instruments. Africans use Shea butter in cooking. In other parts of the world, manufacturers add Shea butter to margarine.
Shea butter is available in different grades, which depend on the extraction method. For best results, unrefined Shea butter, or grade A like vielung shea butter, is preferred. If you have a known allergy to other tree nuts, you may experience a reaction to Shea butter. Consult your physician or allergist before using this product, if this is the case.