Long Overlooked in Parts of Africa, Indigenous Greens Are Now Capturing Attention for Their Nutritional and Environmental Benefits
Total Page：16
File Type：pdf, Size：1020Kb
Super vegetables Long overlooked in parts of Africa, indigenous greens are now capturing attention for their nutritional and environmental benefits. ne lunchtime in early March, tables BY RACHEL CERNANSKY malnutrition is such a problem. We want to see at Nairobi’s K’Osewe restaurant are indigenous vegetables play a role,” says Mary Opacked. The waiting staff run back and productivity and sometimes quality. Abukutsa-Onyango, a horticultural researcher forth from the kitchen, bringing out steaming Now, indigenous vegetables are in vogue. at Jomo Kenyatta University of Agriculture plates of deep-green African nightshade, vibrant They fill shelves at large supermarkets even and Technology in Juja, Kenya, who is a major amaranth stew and the sautéed leaves of cow- in Nairobi, and seed companies are breeding proponent of the crops. peas. The restaurant is known as the best place more of the traditional varieties every year. Scientists in Africa and elsewhere are now to come for a helping of Kenya’s traditional leafy Kenyan farmers increased the area planted ramping up studies of indigenous vegetables green vegetables, which are increasingly show- with such greens by 25% between 2011 and to tap their health benefits and improve them ing up on menus across the city. 2013. As people throughout East Africa have through breeding experiments. The hope is Just a few years ago, many of those plates recognized the vegetables’ benefits, demand that such efforts can make traditional varieties would have been filled with staples such as for the crops has boomed. even more popular with farmers and consum- collard greens or kale — which were intro- This is welcome news for agricultural ers. But that carries its own risk: as indigenous duced to Africa from Europe a little over a researchers and nutritional experts, who argue vegetables become more widespread, research- century ago. In Nairobi, indigenous vegetables that indigenous vegetables have a host of desir- ers seeking faster-growing crops may inadvert- were once sold almost exclusively at hard-to- able traits: many of them are richer in protein, ently breed out disease resistance or some of find specialized markets; and although these vitamins, iron and other nutrients than pop- the other beneficial plants have been favoured by some rural pop- ular non-native crops such as kale, and they traits that made these Women sell African ulations in Africa, they were largely ignored are better able to endure droughts and pests. plants so desirable in nightshade and other by seed companies and researchers, so they This makes the traditional varieties a potent the first place. green vegetables at a lagged behind commercial crops in terms of weapon against dietary deficiencies. “In Africa, “It is important market in Nairobi. 146 | NATURE | VOL 522 | 11 JUNE 2015 © 2015 Macmillan Publishers Limited. All rights reserved FEATURE NEWS that when we promote a specific crop, that we that moringa (Moringa oleifera) is not only one Unlike larger leafy vegetables such as kale, try to come up with different varieties,” says of the most healthful of the indigenous veg- many of the indigenous varieties have small NATURE Andreas Ebert, gene-bank manager at the etables — both nutritionally and medicinally leaves that must be separated from their stems World Vegetable Center (AVRDC), an agricul- — but it is also common in many countries individually before cooking — a laborious tural-research organization based in Shanhua, around the world. process. Recipes are often vegetable-specific; Taiwan. If the increasing popularity of these Research by Abukutsa and others shows spider plant can be cooked with sour milk, for vegetables limits choices, he says, “the major that amaranth greens, spider plant and African example, but cowpea leaves go better with soya benefits we are currently seeing will be lost”. nightshade pack substantial amounts of pro- bean or peanut paste. Although older genera- PETE MULLER/PRIME FOR MULLER/PRIME FOR PETE tein and iron — in many cases, more than kale tions and some rural populations know what PROTEIN FROM PLANTS and cabbage1. These vegetables are generally to do with nearly any local vegetable, much of For Abukutsa, indigenous vegetables bring rich in calcium and folate as well as vitamins the region’s traditional cooking knowledge has back memories of her childhood. Cow’s milk, A, C and E (ref. 2). been lost. So Abukutsa got to work on collect- eggs and some fish made her ill, so doctors ing and testing recipes to maximize the amount advised her to avoid all animal protein. Instead, of iron and other nutrients the dishes contain. the women in her family made tasty dishes out K’Osewe was one of the first restaurants to take of the green vegetables that grew like weeds Researchers an active interest, and others soon followed. around her house. Her mother often cooked risk eliminating For Abukutsa, indigenous vegetables are not the teardrop-shaped leaves of African night- just a research subject — they remain a central shade (Solanum scabrum), as well as dishes of the traits that part of her own diet. “Today at lunchtime, I slimy jute mallow (Corchorus olitorius) and ate pumpkin leaves and nightshade,” she says. the greens of cowpeas, known elsewhere as make indigenous The vegetables’ new-found popularity black-eyed peas (Vigna unguiculata). One is spreading throughout East Africa. At a grandmother always cooked pumpkin leaves vegetables so bustling market in Arusha, a young woman (Cucurbita moschata) with peanut or sesame wearing a light-blue headscarf shops for paste. Abukutsa relished them all and ate the desirable in the sweet-potato leaves (Ipomoea batatas), known greens with ugali, a polenta-like dish common locally as matembele, which have a reputation in East Africa. first place. for improving the blood. She buys them from She chose to pursue a career in agriculture an elderly woman who sells almost exclu- because she wanted to “unravel the potential sively indigenous vegetables under a large red hidden in African indigenous vegetables”, she In recent years, Abukutsa has been studying umbrella that protects her stock from the after- says. Now, she is considered a leader across how to maximize nutritional benefits using dif- noon sun. She says her sales of such plants have Africa, and increasingly around the world, in a ferent cooking methods. Compared with raw climbed substantially over the past five years. robust, rapidly growing field. “She’s almost like vegetables, boiled and fried greens contain the mother of indigenous vegetables in Kenya,” much more usable iron3 and could help to com- GLOBAL APPEAL says Jane Ambuko, head of horticulture at the bat the high rates of anaemia in parts of East Green vegetables are not the only indigenous University of Nairobi. Africa. They can also be important sources of crops attracting researchers’ attention. In the Abukutsa started out in the early 1990s, protein, she says. “Some people just live on veg- 1990s, the US National Research Council surveying and collecting Kenya’s indigenous etables, and they cannot maybe afford meat.” (NRC) in Washington DC convened a panel plants to investigate the viability of the seeds Abukutsa is currently studying the anti to examine the potential of Africa’s ‘lost crops’, that farmers were using. In the decades since, oxidant activity of indigenous vegetables, as including grains, fruits and vegetables. Chaired she has come to focus mainly on the vegetables’ well as how resilient they are to the effects of by renowned agricultural researcher Norman nutritional properties. climate change. Most of the traditional vari- Borlaug, the panel concluded that native plants Today, she is far from alone. The AVRDC eties are ready for harvest much faster than held tremendous potential for improving food has a dedicated research and breeding pro- non-native crops, so they could be promis- security and nutritional intake across Africa, gramme at its office in Arusha, Tanzania, and ing options if the rainy seasons become more and should be a greater focus for researchers4. the Kenya Agricultural and Livestock Research erratic — one of the predicted outcomes of Today, the World Agroforestry Centre in Nai- Organization in Nairobi does similar work. global warming. Slenderleaf (Crotolaria sp.) robi is studying a range of Africa’s more than Other health and agriculture organizations is particularly hardy during drought because 3,000 indigenous fruit species, and finding that in both East and West Africa focus on boost- it quickly establishes its taproot. “If we have they are generally more nutritious, drought- ing consumer use and improving the viability a short rain because of climate change, it can tolerant and pest- and disease-resistant than and yield of these crops. That fits into a global survive,” she says. She is working with other their exotic counterparts. trend emphasizing bioregional foods — using research partners to select vegetables with But vegetables have gained the most notice, crops that are well adapted for a given climate increased tolerance for variations in rainfall both in the marketplace and among research- and environment, rather than foreign plants and temperature. ers. Raymond Vodouhe, a plant breeder and that tend to be less nutritious and require extra Early on, Abukutsa recognized that she geneticist with Bioversity International in water or fertilizers. needed to do more to convince people to add Cotonou, Benin, says that his team’s work in Most of the indigenous vegetables being indigenous vegetables to their diets. Since West Africa has focused on domesticating wild studied in East Africa are leafy greens, almost around 2000, she has led public education vegetables. The hardy wild plants help African all deep green in colour and often fairly bitter. campaigns and worked with restaurants and families to get through periods of drought or Kenyans especially love African nightshade supermarkets around Kenya to find out what crop failure, but are threatened by deforestation and amaranth leaves (Amaranthus sp.).