Indigenous fruits and veggies are smart food for the future
The Western diet has dominated the world for the past 30 years. Currently, diet-related illnesses such as diabetes, hypertension, and heart disease are on the rise. Many consumers prioritize high-calorie, low-nutrient fast food for convenience. Globally, a diet that is characterized by high levels of refined sugars, fat, processed grains, and meats is regarded as detrimental to health. In addition to this, an estimated 9.7 billion people will inhabit the planet by 2050, creating the need for food and nutrition security.1
In 2020, the number of people suffering from hunger increased from 720 to 811 million, particularly as a result of the COVID-19 pandemic.1 It has been demonstrated that underutilized fruit crops can reduce food insecurity as well as malnutrition and “hidden hunger”.2 Although they are packed with carbohydrates, proteins, and fats, underutilized fruits are rarely included in a regular diet. Healthy diets are characterized by a diversity of foods, and one way to improve health is to use indigenous fruit and vegetables.3
In order to achieve food security, affordability and access to food products must be ensured. Hunger, poverty, and malnutrition must be eradicated globally, therefore, nutritional research, product development, and commercialization need to be prioritized in order to improve consumption of indigenous fruits and vegetables.
This article was written by Professor Yasmina Sultanbawa, Professorial Research Fellow at ARC Industrial Transformation Training Centre for Uniquely Australian Foods, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Australia and Professor Dharini Sivakumar, member of the Phytochemical Food Network Research Group, Department of Crop Sciences, Tshwane University of Technology, South Africa.
What are indigenous fruits and vegetables?
Indigenous fruits and vegetables are grown in a traditional food system that is better suited to local conditions and is climate-resilient with low carbon footprints. Indigenous fruits and vegetables are connected to an ethnic group's heritage and culture by their knowledge of local plants. Indigenous fruits and vegetables are also known as “wild” or “native” or underutilised fruits and vegetables. Cleome (Cleome hassleriana), cowpea (Vigna unguiculata), amaranth (Amaranthus cruentus), blackjack (Bidens pilosa), Jew’s mallow (Corchorus olitorius) are some examples of indigenous African leafy vegetables.4 Marula (Sclerocarya birrea), wild apricot (Prunus armeniaca), wild plum (Prunus americana), raisin bush (Grewia flavescens), and sour plum (Ximenia caffra) are among the indigenous fruits found in Africa.5
The popular camu camu (Myrciaria dubia) berries are indigenous fruits from the Amazon rainforest. Since camu camu berries have a tart flavour, they're often found in supplement form as powders, pills, or as juices. Kakadu plum (Terminalia ferdinandiana), Illawarra plum (Podocarpus elatus), Burdekin plum (Pleiogynium timoriense), Davidson’s plum (Davidsonia jerseyana, Davidsonia johnsonii and Davidsonia pruriens), riberry red (Syzygium luehmannii) and yellow finger limes (Citrus australasica), Tasmanian pepper (Tasmannia lanceolata), brush cherry (Syzygium paniculatum), Cedar Bay cherry (Eugenia reinwardtiana), muntries (Kunzea pomifera) and Molucca raspberry (Rubus moluccanus) are the popular indigenous fruits from Australia.6 There are a multitude of aromas to discover in Davidson’s plums beyond their sharp, acidic taste. A total of 6–7 tons of Davidson's plum are harvested annually and used for jams, fruit wines, ice creams and sauces.6
Advantages of indigenous fruit and vegetables
Furthermore, native fruits and vegetables contain vitamins, trace elements, antioxidants and important dietary phytochemicals, which means that diet diversification is a viable and affordable strategy. There is limited information on anti-nutritive compounds in indigenous fruits and vegetables. In comparison with spinach, lettuce, kale, mustard greens, lettuce and other exotic leafy vegetables, African nightshade (Solanum retroflexum) contains a higher amount of protein (6g/100g), Mg (92mg/100g) and Fe (7.2 mg/100g). Indian lettuce (Lactuca indica) contained the most β-carotene (3575.54µg/100g), whereas water dropwort (Oenanthe javanica) contained the most lutein (7439.11µg/100g).7 Cemperai (Champereia manillana), as well as Maman Pasir (Cleome viscose), are consumed by the indigenous Malaysian population as they are rich in antioxidants.7 Furthermore, traditionally grown African leafy vegetables have a high vitamin A content and meet more than 75% of the daily RDA. Communities often struggle with a lack of vegetables during dry seasons, so preserving edible leaves is a strategy to help alleviate this problem. Solar drying and fermentation are traditional methods of extending the availability of African nightshade vegetables.4 After cooking, the leaves are served with cornmeal and tomato relish, or sometimes fermented with milk. Food preparation methods such as these reduce bitter compounds derived from anti-nutrients in the leaves, including glycoalkaloids.4
Indigenous fruits and vegetables contain a variety of bioactive compounds that protect against chronic disease development. Low carbohydrate, high dietary fibre plants provide a low insulin requirement and may have benefited the many indigenous communities in the world from insulin resistance, cardiovascular disease, diabetes, and obesity.8 Davidson’s plum, an indigenous Australian fruit, is rich in sambubiosides of cyanidin, delphinidin, peonidin, pelargonidin and malvidin. In Davidson's plum, the total amount of phenolic compounds, mostly flavonoids, was 1.5 times that of blueberries.9 The native Australian fruit, Kakadu plum, contains approximately 7000mg of vitamin C per 100g of fruit, which is about 100 times the amount of vitamin C found in oranges, making it a true superfood.10 The amount of vitamin C found in Kakadu plum is higher than the amount found in camu camu berries (3000mg/100g).11
Kakadu plums contain a high amount of gallic acid and ellagic acid. For added health benefits, chefs are incorporating the Kakadu plum fruit into sorbet, chutneys, sauces and yoghurt products as purees. Researchers have found that Kakadu plum extracts have excellent anti-inflammatory, antimicrobial, antioxidant and anti-inflammatory properties. Consequently, the plum is now used in the seafood industry to prolong the shelf life of, for example, cooked prawns.
Natural dietary antioxidants are replacing synthetic antioxidants as a current trend for health benefits.7 The antioxidants protect our body cells from damage caused by free radicals, which are potentially dangerous molecules. FRAP (ferric reducing ability of plasma) analysis is one of the best tests to measure antioxidant activity.12 An antioxidant test measures how well foods can neutralize free radicals. On this note, Australia’s Kakadu plum, Illawarra plum, Burdekin plum, Davidson’s plum, riberry, red and yellow finger limes, Tasmanian pepper, brush cherry, Cedar Bay cherry, muntries and Molucca raspberry13 were all identified as exceptional sources of antioxidants like the Amazonian camu camu berries. Similarly, among the 10 indigenous fruits from Southern Africa, Natal plum, Mobola plum (Parinari curatellifolia), Water berry (Syzgium cordatum) and Marula showed the highest antioxidant activity.5 Thus, these fruits can be used as dietary supplements and food additives like the Amazonian camu camu berries.
The sour plum fruit extract was superior to the other tested indigenous fruit extracts and commercial inhibitors in hindering α-glucosidase.14 The 10 indigenous fruits inhibited α-glucosidase activity in the following order: Sour plum fruit extract > Mobola plum > Cape fig (Ficus capensis Thunb) > Transvaal milk plum (Engelerophytum magalismontanum) > Sand apricot vine (Landolphia kirkii) > Water berry > Black monkey orange > Marula > Wild medlar (Vangueria infausta).5 Glucosidase slows digestion, absorption, and postprandial glucose accumulation.14
To determine the safety and toxicity of underutilized crops, studies on cell viability are essential. The ethanolic extract from the Kakadu plum was tested with distinct Caco-2, HT29-MTX-E12, and HepG2 cells, and results revealed the extract was less toxic than previously thought and safe. It is necessary to conduct a comprehensive risk assessment for underutilized crops to assess their safety.15
How to promote utilization and consumption?
Research should be conducted on the nutritional and health benefits of these crops, as well as their cultural significance, to encourage their use. In addition to improving nutrition, other agricultural development policies should increase dietary diversity, as well as address food and nutrition security, health, and poverty. Post-harvest practices play a key role in linking underutilized fruits and vegetables with the supply chain and in generating revenues. Efforts to promote these underutilized vegetables, however, have been hampered by a lack of rules governing water use and production.
- Food and Agriculture Organization of the United Nations (FAO), Making agriculture work for — not against — biodiversity. 29 May 2018. https://www.fao.org/news/story/en/item/1136440/icode/ (accessed: April 2022).
- Schreckenberg K., Awono A., Degrande A., Mbosso C.,Ndoye, O., Tchoundjeu, Z. (2006). Domesticating indigenous fruit trees as a contribution to poverty reduction. Forests, Trees and Livelihoods , 16:1, 35–
- Food and Agriculture Organization of the United Nations (FAO),The State of Food Security and Nutrition in the World 2020. Transforming Food Systems for Affordable Healthy Diets. https://www.fao.org/3/ca9692en/online/ca9692en.html (accessed: April 2022).
- Sivakumar, D., Thi Phan A.D, Slabbert, R.M., Sultanbawa Y., Remize F. (2020). Phytochemical and Nutritional Quality Changes During Irrigation and Postharvest Processing of the Underutilized Vegetable African Nightshade. Front. Nutr., 7 576532.
- Nkosi N.J., Shoko T., Manhivi V.M., Slabbert R.M., Sultanbawa Y., Sivakumar D. (2022). Metabolomic and chemometric profiles of ten Southern African indigenous fruits. Food Chemistry, 381, 132244.
- Sultanbawa Y. (2016). Food Preservation and the Antimicrobial Activity of Australian Native Plants, (2016, CRC Press).
- Kongkachuichai R., Charoensiri R., Yakoh K., Kringkasemsee A., Insung P. (2015). Nutrients value and antioxidant content of indigenous vegetables from Southern Thailand. Food Chemistry, 173:838-46.
- Liu R.H. (2013). Health-promoting components of fruits and vegetables in the diet, , 4(3), 384S–392S.
- Johna O.D., Mouattc P., Prasadam I., Xiaod Y., Panchala S.K., Brown L. (2019). The edible native Australian fruit, Davidson’s plum (Davidsonia pruriens), reduces symptoms in rats with diet-induced metabolic syndrome, Journal of Functional Foods, 56, 204–215.
- Williams D.J.E., Chaliha P.S., Burren B., Tinggi U., Sultanbawa Y. (2016). Organic acids in Kakadu plum (Terminalia ferdinandiana): The good (ellagic), the bad (oxalic) and the uncertain (ascorbic), Food Res Int. 2016 89(Pt 1), 237–244.
- TeruoInoue M.D., Komoda M.S.H., Uchida M.D.T., Node M.D.K. (2008). Tropical fruit camu-camu (Myrciaria dubia) has anti-oxidative and anti-inflammatory properties, Cardiol. 52(2), 127–132.
- Spiegel M., Kapusta K., Kołodziejczyk W., Saloni J., Zbikowska B., Hill G.A., Sroka Z. (2020). Antioxidant Activity of Selected Phenolic Acids–Ferric Reducing Antioxidant Power Assay and QSAR Analysis of the Structural Features, Molecules, 25(13), 3088.
- CSIRO Australia, Native Australian Fruits Bear Sweet Antioxidants, ScienceDaily, 6 August 2007. www.sciencedaily.com/releases/2007/08/070802103444.htm (accessed: April 2022)
- Llorent-Martínez E., Ortega-Barrales P., Zengin G., Mocan A., Simirgiotis M., Ceylan R. & Aktumsk A. (2017). Evaluation of antioxidant potential, enzyme inhibition activity and phenolic profile of Lathyrus cicero and Lathyrus digitatus: Potential sources of bioactive compounds for the food industry. Food and Chemical Toxicology, 107(Pt B), 609–619.
- Akter S., Hong H., Netzel M., Tinggi U., Fletcher M., Osborne S., Sultanbawa Y. (2021) Determination of ellagic acid, punicalagin, and castalagin from Terminalia ferdinandiana (Kakadu plum) by a validated UHPLC-PDA-MS/MS methodology. Food Anal. Methods, 14, 2534–2544.