Macadamia nuts are native to Australia, the macadamia tree is an Indigenous Australian rainforest tree which grows along the eastern coast of New South Wales and Queensland. Approximately 60 million years ago the first macadamia tree evolved in the north east coast. From Port Macquarie to the Atherton Tablelands in the north, half the crop is grown in New South Wales and the other half in Queensland.
Due to the sub-tropical climate they provide optimum growing conditions for the trees, with ideal growth happening between 20-25 degrees Celsius. The macadamia trees can grow to heights of 12 to 15 metres and can take 10 to 15 years before they reach their full growth and harvest potential. Whilst Australia contributes to over 30% of the global crop, macadamia trees can also be found growing in Kenya, Guatemala, Hawaii and South Africa.
According to French culinary chef Bertrand Simon, the macadamia nuts high fat content brings out other flavours extraordinary well, permitting them to be a very versatile ingredient in cooking. A serving of macadamia nuts is 30g which is comparable to 15 nuts (Nuts for Life 2020). They’re very nutritious; providing an abundance of vitamins, minerals and antioxidants which are beneficial to overall health. Macadamias are a source of dietary fibre and protein, they contain good amounts of monounsaturated and polyunsaturated fats and are low in glycaemic index, sugar and sodium. Furthermore, they contain the antioxidant minerals manganese, magnesium and copper.
Additionally, they show an association with the following health benefits.
- Macadamias are a high source of monounsaturated fats and contain polyphenol compounds. Research suggests regular consumption of macadamia nuts reduces oxidative stress and inflammation, thus preventing risk of heart disease (Manohar et al. 2007)
- Full of phytochemicals which have anti-inflammatory and antioxidant properties. The antioxidants work by reutilizing free radicals caused by oxidative stress, reducing cell damage whilst improving cognitive function and overall aging (Manohar et al. 2007)
- Macadamias contain natural plant sterols which contribute to limiting cholesterol reabsorption in the intestines and thus helping reduce LDL cholesterol levels (Patch et al. 2006)
- A source of manganese which contributes to the metabolism of amino acids, carbohydrates and cholesterol and is crucial for bone formation (Aschner & Erikson 2017)
- Tocotrienols, a form of vitamin E that is found in macadamias acts as a preventative factor to diseases such as Alzheimer’s and Parkinson’s due to their antioxidant effect (Bolling et. al 2011)
- 81% of the total fat content of macadamias is from monounsaturated fats (Australian Macadamia Society n.d.). The high monounsaturated fatty acid content of macadamia nuts is understood to reduce the risk of cardiovascular disease, with a study revealing that intake of 42.5g of macadamias daily over 5 weeks reduced serum concentrations of total cholesterol and LDL cholesterol (Griel et. al 2008)
- Nuts including macadamia nuts show an association in managing weight by reducing weight gain and additionally preventing the risk of obesity. This is believed to be due to their fibre and protein content which increases satiety and reduces appetite (de Souza et. al 2017)
- A great source of the water-soluble vitamin, Thiamin, which is imperative for providing the body with energy (Nuts for Life 2020)
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References
Australian Macadamia Society n.d., Australia: the natural home of macadamias, viewed 6 August, 2020, <https://trade.australian-macadamias.org/about-macadamias/>.
Aschner, M, & Erikson, K 2017, ‘Manganese’, Advances in Nutrition,vol.8, no. 3, pp. 520 – 521.
Bolling, BW, Chen, CY, McKay, DL, & Blumberg, JB 2011, ‘Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact factors. A systematic review of almonds, brazils, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts, Nutrition research reviews, vol. 24, no. 2, pp. 244 – 275.
de Souza, R, Schincaglia, RM, Pimentel, GD, & Mota, JF 2017, Nuts and human health outcomes: a systematic review. Nutrients, vol. 9, no. 12, p. 1311.
Griel, AE, Cao, Y, Bagshaw, DD, Cifelli, AM, Holub, B, & Kris-Etherton, PM 2008, A macadamia nut-rich diet reduces total and LDL-cholesterol in mildly hypercholesterolemic men and women, The Journal of nutrition, vol. 138, no. 4, pp. 761 – 767.
Manohar, GL, Blake, RJ, Wills, RBH & Clayton, EH 2007, ‘Macadamia nut consumption modulates favourably risk factors for coronary artery disease in hypercholesterolemic subjects’, Lipids, vol. 42, no. 6, pp. 583 – 7.