Indigenous greens in East Africa capturing attention for nutritional and environmental benefits

Posted on June 11, 2015

The rise of Africa’s super vegetables
Long overlooked in parts of Africa, indigenous greens are now capturing attention for their nutritional and environmental benefits.

Rachel Cernansky
09 June 2015

When Abukutsa pursued her PhD in the 1990s, she was told that indigenous vegetables were not important enough to be the focus of a research project. Now, scientists around the world are studying their benefits and Abukutsa mentors several students working on native plants.

One lunchtime in early March, tables at Nairobi’s K’Osewe restaurant are packed. The waiting staff run back and forth from the kitchen, bringing out steaming plates of deep-green African nightshade, vibrant amaranth stew and the sautéed leaves of cowpeas. The restaurant is known as the best place to come for a helping of Kenya’s traditional leafy green vegetables, which are increasingly showing up on menus across the city.

Just a few years ago, many of those plates would have been filled with staples such as collard greens or kale — which were introduced to Africa from Europe a little over a century ago. In Nairobi, indigenous vegetables were once sold almost exclusively at hard-to-find specialized markets; and although these plants have been favoured by some rural populations in Africa, they were largely ignored by seed companies and researchers, so they lagged behind commercial crops in terms of productivity and sometimes quality.

Now, indigenous vegetables are in vogue. They fill shelves at large supermarkets even in Nairobi, and seed companies are breeding more of the traditional varieties every year. Kenyan farmers increased the area planted with such greens by 25% between 2011 and 2013. As people throughout East Africa have recognized the vegetables’ benefits, demand for the crops has boomed.

Recipes for African super vegetables
This is welcome news for agricultural researchers and nutritional experts, who argue that indigenous vegetables have a host of desirable traits: many of them are richer in protein, vitamins, iron and other nutrients than popular non-native crops such as kale, and they are better able to endure droughts and pests. This makes the traditional varieties a potent weapon against dietary deficiencies. “In Africa, malnutrition is such a problem. We want to see indigenous vegetables play a role,” says Mary Abukutsa-Onyango, a horticultural researcher at Jomo Kenyatta University of Agriculture and Technology in Juja, Kenya, who is a major proponent of the crops.

Scientists in Africa and elsewhere are now ramping up studies of indigenous vegetables to tap their health benefits and improve them through breeding experiments. The hope is that such efforts can make traditional varieties even more popular with farmers and consumers. But that carries its own risk: as indigenous vegetables become more widespread, researchers seeking faster-growing crops may inadvertently breed out disease resistance or some of the other beneficial traits that made these plants so desirable in the first place.

“It is important that when we promote a specific crop, that we try to come up with different varieties,” says Andreas Ebert, gene-bank manager at the World Vegetable Center (AVRDC), an agricultural-research organization based in Shanhua, Taiwan. If the increasing popularity of these vegetables limits choices, he says, “the major benefits we are currently seeing will be lost”.

Protein from plants
For Abukutsa, indigenous vegetables bring back memories of her childhood. Cow’s milk, eggs and some fish made her ill, so doctors advised her to avoid all animal protein. Instead, the women in her family made tasty dishes out of the green vegetables that grew like weeds around her house. Her mother often cooked the teardrop-shaped leaves of African nightshade (Solanum scabrum), as well as dishes of slimy jute mallow (Corchorus olitorius) and the greens of cowpeas, known elsewhere as black-eyed peas (Vigna unguiculata). One grandmother always cooked pumpkin leaves (Cucurbita moschata) with peanut or sesame paste. Abukutsa relished them all and ate the greens with ugali, a polenta-like dish common in East Africa.

She chose to pursue a career in agriculture because she wanted to “unravel the potential hidden in African indigenous vegetables”, she says. Now, she is considered a leader across Africa, and increasingly around the world, in a robust, rapidly growing field. “She’s almost like the mother of indigenous vegetables in Kenya,” says Jane Ambuko, head of horticulture at the University of Nairobi.

Abukutsa started out in the early 1990s, surveying and collecting Kenya’s indigenous plants to investigate the viability of the seeds that farmers were using. In the decades since, she has come to focus mainly on the vegetables’ nutritional properties.
Today, she is far from alone. The AVRDC has a dedicated research and breeding programme at its office in Arusha, Tanzania, and the Kenya Agricultural and Livestock Research Organization in Nairobi does similar work. Other health and agriculture organizations in both East and West Africa focus on boosting consumer use and improving the viability and yield of these crops. That fits into a global trend emphasizing bioregional foods — using crops that are well adapted for a given climate and environment, rather than foreign plants that tend to be less nutritious and require extra water or fertilizers.

Most of the indigenous vegetables being studied in East Africa are leafy greens, almost all deep green in colour and often fairly bitter. Kenyans especially love African nightshade and amaranth leaves (Amaranthus sp.). Spider plant (Cleome gynandra), one of Abukutsa’s favourites for its sour taste, grows wild in East Africa as well as South Asia. Jute mallow has a texture that people love or hate. It turns slimy when cooked — much like okra. Ebert says that moringa (Moringa oleifera) is not only one of the most healthful of the indigenous vegetables — both nutritionally and medicinally — but it is also common in many countries around the world.

Research by Abukutsa and others shows that amaranth greens, spider plant and African nightshade pack substantial amounts of protein and iron — in many cases, more than kale and cabbage1. These vegetables are generally rich in calcium and folate as well as vitamins A, C and E (ref. 2).

In recent years, Abukutsa has been studying how to maximize nutritional benefits using different cooking methods. Compared with raw vegetables, boiled and fried greens contain much more usable iron3 and could help to combat the high rates of anaemia in parts of East Africa. They can also be important sources of protein, she says. “Some people just live on vegetables, and they cannot maybe afford meat.”

Abukutsa is currently studying the antioxidant activity of indigenous vegetables, as well as how resilient they are to the effects of climate change. Most of the traditional varieties are ready for harvest much faster than non-native crops, so they could be promising options if the rainy seasons become more erratic — one of the predicted outcomes of global warming. Slenderleaf (Crotolaria sp.) is particularly hardy during drought because it quickly establishes its taproot. “If we have a short rain because of climate change, it can survive,” she says. She is working with other research partners to select vegetables with increased tolerance for variations in rainfall and temperature. Read More…