The emollient property of nut oils has always been used as the base for most skin improvement formulations. Macadamia nut oil made a late entry into the arena of skin care but its unique composition has made it a must-have in formulations that require deep penetration. Also called Macadamia ternifolia seed oil, it is an important ingredient in griffin+row’s Nourish and Enrich formulations. It is worth cracking open this tough nut to reach the buttery fat that oozes with the goodness that the skin requires.
Introducing Macadamia ternifolia
The genus Macadamia was established in the late 1800s after Dr. Ferdinand von Mueller- the director of the botanical garden at Brisbane- named the tree Macadamia ternifolia after his friend and Scottish scientist John Macadam. It was only in 1956 that the genus was accepted botanically and the member species defined according to the properties of their foliage and seeds 1
Earlier in 1850, Dr. Mueller and his assistant Walter Hill had discovered the smooth shelled macadamia called M integrifolia and the rough shelled macadamia M tetrophylla. Along with M.ternifolia these are the only three species of commercial value. Other trees of the genus Macadamia bear nuts with a high percentage of cyanogenic glycosides that can be poisonous 2. M. ternifolia is a lesser species of the genus with the predominant ones being M. integrifolia and M. tetraphylla 3. The oil extracted from the nuts of these trees is referred to as Macadamia nut oil. In the languages of the aboriginal people of North Eastern Australia, the Macadamia nut is called Kindal, Baupal, Jindill or Boombera 4. It has also been referred to as Gympie nut (after the place where the aboriginals traded the nut) and bitter nut (for its taste), or Queensland nut since this majestic tree is found in Queensland, Australia 5, Maroochi nut, Bush nut or Hawaii nut 3.
- ternifolia is found in Queensland, towards Moreton Bay while the other members of genus Macadamia are native to New South Wales.
The Macadamia tree is unique is that it is the only endemic Australian species to be successfully cultivated outside the country. Several countries including Brazil, Costa Rica, Israel, Kenya, Bolivia, New Zealand, Colombia, Guatemala and Malawi have thriving plantations. The leading exporters of the nut are South Africa, Malaysia, Australia, USA and Israel 2.
Traditional uses of Macadamia nut
Australian aboriginal people of the North east valued and revered the Macadamia. It was associated with heroes of their legends 3 and annual migration was timed according to the time of ripening of the nuts. The nuts themselves were considered a delicacy and women collected them as a special feast. These people knew exactly how to break open the hard case using stones with special indentations in order to obtain the kernel with minimal damage. More importantly, they knew which species of Macadamia yields edible nuts 1.
When European settlers came to the east coast, the aboriginals traded macadamia nuts for liquor and tobacco. It took a while for German explorer Friedrich Leichhardt to actually find the trees in Moreton Bay off the coast of Queensland and describe them as well as the nuts. Even then the settlers looked upon the giant trees as ornamental trees with dark glossy leaves and small, mildly fragrant flowers.
In the 1850s Walter Hill –the superintendent of Brisbane’s Botanical garden – became the first European to taste Macadamia nuts. Apparently, he was horrified that the assistant who had been asked to crack open some nuts for germination had consumed some of them. When the boy lived out the week, Hill ventured to consume the nuts and found them appealing to the palette 2.
In 1881, William Purvis, the manager of a sugar mill in Hawaii, brought back Macadamia seeds to grow the trees as a wind-breaker for sugarcane plantations. Macadamia then became a plantation crop on the island of Oahu in 1922. The 1930s saw the commercial production of Macadamia nuts and candies. Ellen Dye Candies and the Alexander Young Hotel candy started making chocolate covered candies. In 1939 the famous Menaheune Mac brand of macadamia nut chocolates began production 6.
Macadamia leaves serve as food for certain Lepidopteran species. The nuts are fed to hyacinth macaws which are capable of cracking open the hard shell to reach the kernel of the nut 2.
The analysis of macadamia nut oil triggered interest in the nutritional value of the nut. With a high percentage of palmitoleic acid, macadamia nut is now ranked high on the list of foods to fight the metabolic syndrome. It is also valued for its use as skin- repair oil.
Bioactivity and associated components of the plant
The only component of the Macadamia plant that has been exploited for its bioactivity is the seed kernel. Encased in an extremely hard shell, the kernel is made of 80% fat, 4% protein and 8% carbohydrate. It is also rich in phytosterols and vitamins C, E, thiamine, riboflavin, niacin, folate, pyridoxine and pantothenic acid. A high percentage of calcium, magnesium, phosphorus and potassium and significant amounts of iron, copper, manganese, magnesium, zinc and selenium make the nut highly mineral-rich 7.
The oil extracted from the kernel has a pale yellow colour and is not viscous. It comprises the following 8
- 16% saturated fat – palmitic, stearic and eicosanoic acid (arachidic acid)
- 3% polyunsaturated fat (PUFA) – Linoleic acid
- 81% monounsaturated fatty acids (MUFA) – oleic acid, palmitoleic acid and linoleic acid
- Phytosterols- β-sitosterol, campesterol and stigmasterol 9
- α-tocopherol 9
- Squalene 9
The composition of the Macadamia nut oil – especially the presence of palmitoleic acid and squalene- allows it to be easily absorbed by the skin and hair.
Palmitoleic acid and squalene– a spotlight on the main active bioactive component
- Palmitoleic acid is a long chain fatty acid
Palmitoleic acid is 9-cis- hexadecenoic acid. Along with oleic acid it is required for the regeneration of keratinocytes in skin. Among plants, it is found only in macadamia seed oil and sea buckthorn. Macadamia seed oil closely resembles human sebum due to palmitoleic acid, PUFAs and oleic acid 10
- Squalene is a tri-terpenoid.
Squalene is an intermediate in the synthesis of cholesterol which maintains the fluidity of cell membranes. As an important constituent of the outer layer of skin (stratum corneum), low squalene is associated with dry and damaged skin 11. Macadamia nuts, Brazil nuts, pecans, pistachios and walnuts are good sources of squalene.
General health benefits and uses of Macadamia seed oil:
Most of the properties and benefits of Macadamia seed oil in the context of skin and hair care have been anecdotal. However, with the increasing popularity and better availability, more and more people have endorsed the positive effects of the oil. Scientific evidence of the benefits of Macadamia seed oil is largely with respect to balance of lipid metabolism when taken internally.
Macadamia nut oil is obtained by cold pressing the shelled nuts. The oil is light and non-greasy. It is extremely stable and has a shelf life of 1-2 years. It can be used either for topical applications or for internal consumption.
Topical application of macadamia seed oil:
Due to its unique composition, the oil has become popular with skin restructuring and repair formulations. The following are the uses of the oil-
- Anti-ageing: The palmitoleic acid and squalene present in macadamia seed oil prevents the premature formation of wrinkles by boosting the regeneration of skin keratinocytes. Linoleic acid also helps to reduce trans-epidermal water loss, keeping the skin well-hydrated and supple 10. The hydrating quality of the oil is useful for dry skin, mature skin, baby skin, lip balms and restructuring creams (especially for use around the eyes) 8.
- Anti-inflammation: The phytosterols in macadamia seed oil help to reduce itchiness and inflammation, thereby decreasing rash formation.
- Anti-oxidant property: Palmitoleic acid and squalene also prevent lipid peroxidation and reduces skin cell damage 10.
- Skin restructuring and regeneration: With its high percentage of oleic, linoleic and palmitoleic acid, the oil helps to treat stretch marks, reduce scars and prevent chapping. It nourishes the skin and is a good moisturising agent 8. It is also included in enriching oils for dry and frizzy hair
Use of macadamia seed oil as an oral therapeutic:
Given the lipid composition of macadamia seed oil, it is recommended as a therapeutic to maintain a healthy lipid profile. The phytosterols help in reducing cholesterol levels while the PUFAs and MUFAs keep the right balance of lipids.
Botany and grow it yourself
The Macadamia belongs to the family Protaceae. It is an imposing, slow- growing tree that can rise to a height of 18-20 metres. It has dark green glossy oblong leaves that are arranged in whorls of three to six, with serrated margins. The white pink or purple fragrant blossoms appear on a long slender raceme. The fruit is hard and woody with one or two seeds inside it.
In Australia, the trees are native to the eastern side of the Great Dividing range on the east coast. Otherwise, the trees grow best in fertile, well-drained soil, temperatures between 25-28° C and moderate rainfall. Volcanic soils and tropical weather also suit the growth of the tree 8.
Macadamia trees are normally propagated by grafting. They take 5-7 years to reach their full potential of fruit bearing. The trees start blooming in September and the nuts start forming in December. The fully mature nuts take until March the next year to ripen and fall to the ground. The nuts are covered in a dark green husk which splits open. The extremely hard and thick case that encloses the seeds has to be racked open using tremendous pressure. The white creamy kernel is made of 80% fat from which the oil is obtained by cold pressing 12.
The trees can stand for up to 100 years. However, they have a shallow root system which makes them susceptible to being blown down during storms.
Cyanogenic glycosides: Cyanogenic glycosides are metabolites that are present in several edible parts of plants. As the name implies, these compounds release cyanide (hydrocyanic acid) when chewed. It is only in some plants that the levels of cyanogenic glycosides are high enough to cause toxicity in humans.
Phytosterol: Phytosterols are a class of compounds related to cholesterol that are produced by plants. Phytosterols can help bring down circulating cholesterol levels since they act as competitors for the same enzymes.
Sebum: Sebum is the oily secretion of the sebaceous glands of the skin. It is important in lubricating the skin and keeping it waterproof. In humans, the maximum number of sebaceous glands occurs on the scalp and face. The excess production of sebum leading to the clogging of the pores on the skin is a major cause of acne.
- Shigeura G and Hiroshi O. (1984). Macadamia nuts in Hawaii: History and Production. University of Hawaii. p13. Retrieved from https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-039.pdf (19th August 2017).
- (2017). Retrieved from https://en.wikipedia.org/wiki/Macadamia (19th August 2017).
- The Bopple Nut. (Undated). Retrieved from http://www.bauplemuseum.com/bopple%20nut%20pub.pdf (19th August 2017).
- History of the Macadamia. (Undated). Retrieved from http://www.australian-macadamias.org/consumer/our-story/history-of-the-macadamia (19th August, 2017).
- Macadamia oil. (Undated). Retrieved from http://www.centerchem.com/Products/DownloadFile.aspx?FileID=6847 (23rd August 2017)
- Schmitt RC. (Undated). Macadamia nuts. Retrieved from https://www.hawaiianhistory.org/time-capsules/firsts/macadamia-nuts/ (19th August 2017)
- Nuts, Macadamia nuts, raw nutrition facts and calories. (2014). Retrieved from http://nutritiondata.self.com/facts/nut-and-seed-products/3123/2 (24th August 2017).
- Macadamia oil (Refined). (2007). Retrieved from http://glenncorp.com/wp-content/uploads/2014/07/TDS-Macadamia-Oil-Refined-230608.pdf (24th August 2017).
- Maguire LS, O’Sullivan SM, Galvin K, O’Connor TP, O’Brien NM. (2004). Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut. International Journal of Food Science and Nutrition 55:171-178.
- Miller S. (2013). Benefits of Macadamia nut oil in skin care. Retrieved from http://thenakedchemist.com/benefits-of-macadamia-nut-oil-in-skin-care/ (24th August 2017).
- Boussouira B and Pham DM. (2016). Squalene and Skin Barrier Function: From Molecular Target to Biomarker of Environmental Exposure. Ch. 2.In Skin Stress Response Pathways, G.T. Wondrak (ed.). Springer International Publishing Switzerland, pp 29-48.
- Macadamia nuts. (Undated). Retrieved from https://www.macadamia.com.au/characteristics/ (19th August 2017)