Table of contents:
The shea tree Vitellaria paradoxa is indigenous to Africa and grows wild across a belt of savanna extending from Senegal, Mali, Côte d’Ivoire, Burkina Faso, Togo, Ghana, Benin, Nigeria, Niger, Cameroon to further east in Uganda, Sudan and Ethiopia. Shea butter is extracted from the kernels of shea nuts, the seeds of the shea tree, by roasting and pressing the kernels, churning the obtained liquid with water, boiling, sieving, and cooling.
Shea butter is traditionally used as an edible oil in African cuisine and as a treatment for rheumatism, nostril inflammation, leprosy, soothing and healing following circumcision, and for preventing pregnancy stretch marks. Internationally, it has been used as a cocoa butter equivalent for manufacturing chocolate, and in the cosmetics and personal care industries due to its emollient, anti-inflammatory and antioxidant activities. Because shea butter contains saponifiables, it can also be used for soap-making.
As a rule, shea butter consists of more than 90% triglycerides and a minor but significant (4-11%) unsaponifiable fraction, More than 50% of the triglyceride fraction is unsaturated fatty acids, especially stearic and oleic acids. The exact composition varies both between and within countries however. For instance, shea butter from West Africa generally contain higher levels of triterpene alcohols, triterpene esters and stearic acid,, whereas shea butter from East Africa have significantly higher oleic acid content. The amount of tocopherols (vitamin E) in shea butter also exhibits regional variation, with shea butter from shea tree populations situated in hot, dry climates having the highest levels of alpha-tocopherols and those from cooler highland areas having the lowest concentrations, especially in northern Uganda. These variations have been linked to differences in climate, latitude and elevation.
Interestingly, the shea kernels contain polyphenols such as gallic acid, catechin, epicatechin, epicatechin gallate, gallocatechin, epigallocatechin, gallocatechin gallate, and epigallocatechin gallate as well as quercetin and trans-cinnamic acid, while the pulp is rich in ascorbic acid (vitamin C).
Although shea butter's high fat content would seem to favour its absorption into the skin, we were unable to find any published studies on permeation data. One patent does mention that shea butter is absorbed rapidly into the skin without leaving a greasy feeling. Interestingly, another patent filed in 1987 claims that the penetration of shea butter through epidermal tissue may be facilitated by the co-application of sodium stearoyl lactylate with sucrose cocoate and and stearoyl lactylic acid with sucrose cocoate, and a more recent patent filed in 2012 was for the use of shea butter as a transdermal penetration enhancer.
3. Effects on the skin
3.1 Age-related improvements
Though shea butter is employed as a natural emollient in traditional Nigerian medicine and is also mentioned in patents as an emollient, moisturizer and skin conditioner, a literature search did not turn up any studies to substantiate its moisturizing or skin softening effect. Also, shea butter contains fatty acids that are known to influence barrier recovery, but when tested it did not decrease the degree of skin irritation caused by sodium lauryl sulphate, unlike canola oil.
A topical anti-wrinkle and antiaging moisturizing cream containing shea butter among other ingredients and a cosmetic combination of shea butter and cocoa butter to treat dry or chapped skin have been patented, but to our knowledge their clinical benefits have not been confirmed via clinical testing.
3.2 Anti-inflammatory effect
Several studies have verified the anti-inflammatory effects of shea butter. In one, an ointment made from an extract of Khaya senegalensis, petrolatum, lanolin and shea butter inhibited ear edema in a dose-dependent manner, and in another, a methanolic extract of shea butter reduced the levels of lipopolysaccharide (LPS)-induced nitric oxide, TNF-α and interleukins in a murine macrophage cell line, in addition to inhibiting the expression of proinflammatory enzymes, inducible nitric oxide synthase (iNOS) and COX-2. These results are not surprising as shea butter is a significant source of anti-inflammatory compounds such as triterpene acetate and cinnamate esters. They also provide a plausible explanation for shea butter's effectiveness in nasal decongestion, which is associated with inflammatory edema of the upper respiratory mucosa.
3.3 Other uses
Atopiclair, a topical non-steroidal anti-inflammatory agent for the treatment of atopic dermatitis, contains shea butter as one of its ingredients, albeit not one of the main ones. For this reason, it is probably far-fetched to conclude that shea butter helps relieve atopic dermatitis, despite Atopiclair's proven efficacy over multiple clinical trials.
4. Side Effects
The safety of topical shea butter is not well-studied, but it seems to be reasonably well-tolerated -- normal skin treated with shea butter resulted in only barely perceptible erythema in some individuals 24 hours after patching. Even on skin that had been damaged by sodium lauryl sulphate, the application of shea butter did not cause irritation in 7 out of 21 subjects, led to barely perceptible erythema in 6 subjects, slight erythema in 1 subject, and moderate erythema in only 1 subject. Topical use of shea butter-based products is also safe for individuals with nut allergy, as shea butter appears to have low potential allergenicity.
- Nahm HS, Juliani HF, Simon JE. Effects of Selected Synthetic and Natural Antioxidants on the Oxidative Stability of Shea Butter (Vitellaria paradoxa subsp. paradoxa). JMAP. (2012)
- Honfo FG, et. al. Nutritional composition of shea products and chemical properties of shea butter: a review. Crit Rev Food Sci Nutr. (2014)
- Peers KE. The non-glyceride saponifiables of shea butter. J Sci Food Agric. (1977)
- Warra AA, et. al. Soap production From shea nut butter. International Journal of Natural and Applied Sciences. (2009)
- Akihisa T, et. al. Triterpene alcohol and fatty acid composition of shea nuts from seven African countries. J Oleo Sci. (2010)
- Okullo JBL, et. al. Physico-chemical properties of shea butter (Vitellaria paradox C.F. Gaertn.) oil from the shea districts of Uganda. AJFAND. (2010)
- Di Vincenzo D, et. al. Regional variation in shea butter lipid and triterpene composition in four African countries. J Agric Food Chem. (2005)
- Akihisa T, et. al. Triacylglycerol and triterpene ester composition of shea nuts from seven African countries. J Oleo Sci. (2011)
- Davrieux F, et. al. Near infrared spectroscopy for high-throughput characterization of Shea tree (Vitellaria paradoxa) nut fat profiles. J Agric Food Chem. (2010)
- Maranz S, Wiesman Z. Influence of climate on the tocopherol content of shea butter. J Agric Food Chem. (2004)
- Maranz S, Wiesman Z, Garti N. Phenolic constituents of shea (Vitellaria paradoxa) kernels. J Agric Food Chem. (2003)
- Blomberg AM. Topical skin composition comprising shea butter, jojoba oil, petroleum jelly, stearic acid, magnesium sulfate, zinc oxide, glycerin, and water. US Patent 8673328 (2014)
- Goode ST, Linton RR, Baiocchi F. Mixture of sucrose fatty acid ester and acyl fatty acid lactylate ester. US Patent 4822601 (1989)
- Wu WL, et. al. Use of shea butter as transdermal osmosis promoter. China Patent 102671212 (2012)
- Tella A. Preliminary studies on nasal decongestant activity from the seed of the shea butter tree, Butyrospermum parkii. Br J Clin Pharmacol. (1979)
- Holloway Durr, et. al. Hand and body creme for the treatment of skin ailments. US Patent 5997889 (1999)
- Modak S, Gaonkar TA, Sampath L. Gentle-acting skin disinfectants. US Patent 6846846 (2005)
- Mao-Qiang M, et. al. Exogenous nonphysiologic vs physiologic lipids. Divergent mechanisms for correction of permeability barrier dysfunction. Arch Dermatol. (1995)
- Lodén M, Andersson AC. Effect of topically applied lipids on surfactant-irritated skin. Br J Dermatol. (1996)
- Armand G. Topical anti-wrinkle and anti-aging moisturizing cream. US Patent 20100098794 (2010)
- Thioune O, et. al. Inflammatory ointment from shea butter and hydro-alcoholic extract of Khaya senegalensis barks (Cailcederat). Dakar Med. (2000)
- Verma N, et. al. Anti-inflammatory effects of shea butter through inhibition of iNOS, COX-2, and cytokines via the Nf-κB pathway in LPS-activated J774 macrophage cells. J Complement Integr Med. (2012)
- Akihisa T, et. al. Anti-inflammatory and chemopreventive effects of triterpene cinnamates and acetates from shea fat. J Oleo Sci. (2010)
- Veraldi S, et. al. Treatment of pruritus in mild-to-moderate atopic dermatitis with a topical non-steroidal agent. J Drugs Dermatol. (2009)
- Belloni G, Pinelli S, Veraldi S. A randomised, double-blind, vehicle-controlled study to evaluate the efficacy and safety of MAS063D (Atopiclair) in the treatment of mild to moderate atopic dermatitis. Eur J Dermatol. (2005)
- Abramovits W, et. al. A multicenter, randomized, vehicle-controlled clinical study to examine the efficacy and safety of MAS063DP (Atopiclair) in the management of mild to moderate atopic dermatitis in adults. J Drugs Dermatol. (2006)
- Boguniewicz M, et. al. MAS063DP is effective monotherapy for mild to moderate atopic dermatitis in infants and children: a multicenter, randomized, vehicle-controlled study. J Pediatr. (2008)
- Patrizi A, Raone B, Neri I. Atopiclair. Expert Opin Pharmacother. (2009)
- Abramovits W, et. al. Patient-reported outcomes from a multicenter, randomized, vehicle-controlled clinical study of MAS063DP (Atopiclair) in the management of mild-to-moderate atopic dermatitis in adults. J Dermatolog Treat. (2008)
- Patrizi A, et. al. A double-blind, randomized, vehicle-controlled clinical study to evaluate the efficacy and safety of MAS063DP (ATOPICLAIR) in the management of atopic dermatitis in paediatric patients. Pediatr Allergy Immunol. (2008)
- Chawla KK, et. al. Shea butter contains no IgE-binding soluble proteins. J Allergy Clin Immunol. (2011)