The softening and hydrating work of shea butter

When one thinks of Africa, one automatically associates it with its exotic fauna. Not many are aware of the unique flora that is found in this continent. Even less is known about the traditional knowledge associated with these flowering plants and trees. The Shea butter nut tree is a classic example of Nature’s bounty in the harsh and dry terrain of sub-Saharan Africa. Africans have exploited its curative effects on the skin from centuries and now, the benefits are being enjoyed by the rest of the world. No wonder then, that shea butter is a constituent of griffin+row’s Nourish and Enrich formulations.

Introducing Vitellariaparadoxa – the Shea butter tree 

The shea butter tree was given the botanical name of Butyrospermumparkii after the butter content of the nut (butyro= butter in Latin) and the Scottish explorer- Mungo Park- who came across the tree in Senegal1. It is now placed under the genus Vitellaria. Of the two species of Vitellaria, the species paradoxa is found from Senegal to the Central African Republic. The other species nilotica is found in the east African countries of Uganda, north –east Zaire, southern Sudan and up to the foothills of the Ethiopian highlands2. The shea tree is scattered throughout the entire Sudano-Sahel belt that stretches from Sudan in the east to the sub-Saharan countries of West Africa.

The common name ‘shea’ comes from ‘shiyiri’- the name for the tree in the Bambhara language of Mali. It is also called karite nut tree 3, bambouk butter tree or galam butter tree. In native languages it is referred to as balire/kareje in Fula, man ka’dai/kadanya in Hausa, okwuma in Igbo, an-doni in Temne and akumalapa/emi-emi in Yoruba4.The Arabs who traded with North African countries called shea butter ‘lulu’ which is Arabic for pearl.

The increasing demand for shea butter in the United States, the European Union, Japan, India and Canada has made Vitellaria an important cash crop for these countries. Today, it is among the top ten exports from Ghana and is the most important export from Burkina Faso after gold, cotton and livestock 5.

Traditional uses of Vitellaria paradoxa (Shea nut tree) 

The Shea nut tree is revered in Africa for its wood and fruit. The wood is hard, termite- resistant and fire-resistant and was used to make royal coffins. Today the wood is used to make furniture, household utensils, railway sleepers etc. It is used sparingly as firewood since it is valued more for the fruit and nut.

Shea tree bark is an important ingredient in African black soap, locally called Ose dudu or Dudu osun. The soap is traditionally made in the West African countries of Nigeria and Ghana and is a natural moisturiser and mild cleanser. Bathing with a decoction made from shea bark is recommended at childbirth in Cote d’Ivoire while the bark extract is used as an antidote for the venom of the spitting cobra. Bark infusions are also used to treat leprosy, diarrhoea, dysentery and gastric problems.

The latex from the tree is mixed with palm oil to make glue that is used for minor repairs [4].

Flowers of the shea nut tree are fried as fritters and consumed. The sweet pulp of the fruit of the Vitellaria tree plays an important role in the nutrition of the native people and animals of sub-Saharan African countries 2.

The nut is consumed raw or lightly roasted. Butter from the kernel is sold as ‘loaves’ in the local market and has a good keeping quality if properly wrapped, to be used in cooking.The waxy butter is suitable for candle making 4.

Of course the curative properties of the butter have been known from centuries. It is said that even Queen Cleopatra used to carry the butter to maintain her beauty regimen in the harsh North African climate. The butter has been extensively used on burns, wounds and insect bites 6.

The waste water generated from the extraction of butter is effective in keeping away white ants and other pests 4.

The seed is used in traditional medicine to treat wounds, sprains and arthritic joints. It is also effective as a decongestant 3.

The tree plays an important role in the prevention of soil erosion in traditional agricultural practices 3.

The tree was known to Europeans since the 1300s. However, the benefits of shea nut butter have become common knowledge only in the last few decades. Owing to its similarity with cocoa butter, shea butter is now used in making chocolates. It has also been converted to biodiesel and used in pharmaceutical formulations.

The acknowledgement of the importance of shea butter in cosmetic formulations has played a major role in improving the economic status of women in sub-Saharan African countries 5.

Bioactivity and associated components of the plant 

The pulp of the fruit is a rich source of nutrients. It contains sugars, proteins, calcium, ascorbic acid, and iron 2.

The colour of shea butter can range from beige to yellow. Raw, unrefined butter can be golden yellow and upon refinement, the colour is off-white or ivory. It also has a mild fragrance somewhat like that of almond oil 7.It is mainly composed of the following fatty acids-

Unsaturated fatty acids: Palmitic acid, stearic acid and arachidic acid.

Monounsaturated fatty acids: Oleic acid

Polyunstaurated fatty acids: Linoleic acid.

The other components include-

  • Polyphenols: The unsaponifiable portion of shea butter contains a large percentage of phenolics and catechins. At least eight catechins have been isolated from shea nut. Gallic acid is the main catechin, while smaller amounts of catechin, epicatechin, epicatechingallate, gallocatechin, epigallocatechin and gallocatechingallate are present. Quercetin and trans-cinnamic acid are the other important polyphenols found in Shea butter 8.
  • Triterpene alcohols:24-methylenelanost-9(11)-en-3-ol, dammaradienol, 24-methylenedammarenol
  • Sterols: α-spinasterol and Δ7-stigmastenol. 

Shea butter is unique among plant oils/butters in that the sterols and triterpenes are found esterified to cinnamic and other monounsaturated fatty acids 9. In addition to these compounds, the butter is rich in vitamins A and E and minerals.

Stearic acid and cinnamic acid (ester): a spotlight on the active components

  • Stearic acid is a long chain saturated fatty acid 10.

The chemical name for stearic acid is octadecanoic acid. It is the major fatty acid found in shea butter and cocoa butter. It is found in both animal fat and some plant oils and is a waxy solid at room temperature. Like palmitic or palmitoleic acid, it is known to help retain moisture in the skin, keeping it flexible and elastic. This leads to a younger looking skin in which the formation of wrinkles is delayed.

  • Cinnamic acid is an acidic polyphenol.

Cinnamic acid esters are formed when these polyphenols combine with organic acids. These compounds are known to be natural sunscreens 11. They are also effective in depigmentation of scars and restructuring the skin. In shea butter, cinnamic acid along with gallic acid has an anti-ageing effect on the skin.

Benefits and uses of shea butter

Shea butter is extracted from the roasted seeds of the fruits. The texture of the butter depends largely on the time and temperature of roasting. These days, mechanised roasting and extraction has standardised the quality of the butter extracted. When properly packaged the butter has a shelf life of nearly 10-15 months.

Shea butter, like cocoa butter has a high percentage of saturated fatty acids. This enables the butter to act as a carrier for deep penetration of the skin. When added to formulations, it assists in the delivery of compounds for repair and rejuvenation. Listed below are some properties of shea butter that can be attributed to the presence of polyphenols and fatty acids 12,13

Wound healing: Shea butter is known to heal wounds, scratches, diaper rash and sunburn. It is also effective in the treatment of burns and augments the renewal of skin cells in the wounded region. It reduces the pigmentation of scars and when used on normal skin, evens out the skin tone. It is recommended to be used as an overnight cream to treat chapped elbows and cracked heels.

Moisturising effect:The deep penetration of fatty acids acts as a natural moisturiser. This rejuvenates ageing skin and eliminates wrinkles. Regular use can get rid of stretch marks. The stearic acid in the butter keeps the loss of trans-epidermal moisture under control.

Anti-inflammatory effect: Shea butter applied on insect bites and skin rashes provides immediate relief. It is also effective in relieving the discomfort of eczema and dermatitis. For sensitive skin, it makes a soothing after-shave moisturiser.

Anti-microbial effect: There is some scientific evidence that cinnamic acid esters have anti-microbial action 14. This may explain the antiseptic effect of shea butter.

Shea butter is now used in cosmetic formulations for anti-ageing and skin rejuvenation. It is not only incorporated into soaps and shampoos, but also in massage oils and lotions.  It is also a natural hair conditioner.

Botany and grow it yourself3,4

The shea nut tree belongs to the family Sapotaceae (soapberry family). It is a large tree that grows up to 20 m in height. The trunk is straight and branches are dense forming a crown of leaves that spreads out on the top. It resembles the oak in size and appearance. The bark of the tree is remarkably fire-resistant, with deep fissures.

Leaves are leathery, oblong in shape and are clustered at the ends of branches. Young leaves are reddish-brown and turn a dark green as they age.

Flowers form from 2-year old buds that emerge among the leaves in clusters. Inflorescence can be cream to brown in colour and last for 30-75 days. The flowers are hermaphroditic and can be self-pollinated.  Pollination is also insect dependent. Fruit are borne on stalks, have a round or elliptical shape and take 4-6 months to mature. The greenish-yellow pulp is nutrient rich and surrounds the hard, thin-shelled seed. The shea ‘nut’ is the kernel of this seed. Harvesting the seed and processing it in a traditional manner is usually done by women.

Shea trees grow well in semi-arid conditions and are remarkably drought resistant. They have a deep root system that allows them to survive the harsh summers of the savannah. The tree prefers loose sandy soil and needs plenty of sunlight. 

Shea trees take almost 10-15 years to bear fruit and the full capacity is seen only after 50-60 years. The trees are known to survive for nearly 200 years under inhospitable weather conditions. Yet, they are now listed as endangered since the wood of the trees are used for various purposes. However, thanks to traditional agroforestry methods that used the trees, there are several thousand of them scattered across Africa. Shea trees are extremely difficult to propagate, and only in recent years plantations have been established. This has also enabled the cultivation of the tree outside Africa such as in the Dominican Republic and the Honduras.

Glossary

Unsaponifiables: The part of oils/fats that cannot be converted to soap is called the unsaponifiable fraction of the oil/fat.

Catechins: Catechins are flavonols that are formed as secondary metabolites in plants. Catechins have high anti-oxidant activity.

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References

  1. Vitellaria paradoxa. (2017). Retrieved from https://en.wikipedia.org/wiki/Vitellaria 14th September 2017.
  2. Gezahegn YA, Emire SA and Asfaw SF. (2016). Optimization of Shea (Vitellariaparadoxa) butter quality using screw expeller extraction. Food Science & Nutrition, 4(6): 840–847.
  3. Schmidt M. (2012). Vitellaria paradoxa F. Gaertn. Retrieved from http://eol.org/pages/1149436/overview (14thSepetember, 2017).
  4. Orwa C, Mutua A, Kindt R, Jamnadass R and Anthony S. (2009). Vitellaria paradoxa. AgroforestreeDatabase:a tree reference and selection guide version0 (http://www.worldagroforestry.org/sites/treedbs/treedatabases.asp)
  5. Nde DB, Boldor D, Astete C, Muley P and Xu Z. (2016). Oil extraction from sheanut (Vitellariaparadoxa Gaertn C.F.) kernels assisted by microwaves. Journal of Food Science and Technology.  53(3):1424–1434.
  6. What is shea butter?(2017). Retrieved from http://www.simplysheabutter.com/what-is-shea-butter/(14th September 2017).
  7. Megnanou R-M and Niamke S. (2015). Improving the optimized shea butter quality: a great potential of utilization for common consumers and industrials. SpringerPlus, 4: 667- 677.
  8. Maranz S, Wiesman Z and Garti N. (2003). Phenolic constituents of shea (Vitellaria paradoxa) kernels. Journal of Agricultural and Food Chemistry. 51(21): 6268-6273.
  9. Peers KE. (1977). The non-glyceride saponifiables of shea butter. Journal of the science of food and agriculture 28(11): 1000-1009.
  10. Stearic acid. National Center for Biotechnology Information. PubChem Compound Database; CID=5281, https://pubchem.ncbi.nlm.nih.gov/compound/5281 (accessed Sept. 16, 2017).
  11. Akihisa T, Kojima N, Kikuchi T, Yasukawa K. Tokuda H, Masters ET, Manosoroi A and Manosoroi J. (2010). Anti-inflammatory and chemopreventive effects of triterpene cinnamates and acetates from Shea fat. Journal of Oleo Science 49(5): 273-280.
  12. Carter P.(Undated). An introduction to shea butter. Retrieved from https://www.sheainstitute.com/wp-content/uploads/2012/12/ASBI-Sheaducation.pdf (15th September 2017).
  13. Dennie, MaKeish N., “Medical Benefits of the Shea Nut Tree” (2012). Biology Student Research. Paper 1. Retrieved fromhttp://digitalscholarship.tnstate.edu/biology_students/1 (15th September 2017).
  14. Guzman JD. (2014). Natural Cinnamic Acids, Synthetic Derivatives and Hybrids with Antimicrobial Activity. Molecules 19:19292-19349.