If you walk through a vegetable garden in Zimbabwe, whether in a town or a rural area, it is likely that you will wade through a ‘sea’ of blue-green leaves belonging to either rape or covo. Covo is the favourite vegetable in this country today, eaten daily as an accompaniment to the staple sadza. Things were not always so. Covo, which is a type of kale and a member of the cabbage family, was introduced to Africa about a century ago. Before then a wide range of indigenous and naturalised greens were regularly consumed and these are undergoing something of a revival across Africa according to a recent article in Nature.
The pros and cons of covo
There is not much wrong with covo from a nutritional point of view. It is rich in vitamin C and K with calcium, folate, fibre and also contains anti-cancer nutrients. Covo also has the advantage of producing leaves which can be picked daily for many months. The main health problem with a diet rich in kale is that it can lead to thyroid problems if eaten in excess.
From a cultivation perspective, covo presents several agricultural challenges. Like all members of the brassica family (including cabbage, rape, tsunga, broccoli and cauliflower) covo is a heavy feeder needing rich, fertile soils. In addition because it is native to cooler climates, covo is very susceptible to attacks from pests and diseases, a problem which is exacerbated by the way it is usually cultivated in dense monocultures which are kept for months or even years without any crop rotation.
Covo threatens nutritional diversity
Nutritionists tell us that it is not a good idea to eat the same thing every day. In order to obtain all of the nutrients for good health we are encouraged to eat a wide range of different fruits and vegetables which means that eating only covo as our daily vegetable is not a good idea. The UK government recommends eating at least five portions of different vegetable and fruit daily. In other parts of Europe the recommendations are even higher. In Zimbabwe we have no official quantitative guide and local nutritionists are often heard complaining that the local diet has become extremely monotonous.
Super vegetables to the rescue
It seems that the time is ripe to return to some of the traditional vegetables which used to be widely grown and consumed in Zimbabwe. These, including mowa/ bonongwe/ imbuya (Amaranthus hybridus), nightshade/ musaka/ ixabaxaba (Solanum nigrum) and spiderleaf/ nyeve/ilude (Cleome gynandra), are eaten more frequently in countries to the north such as Zambia, Malawi and Mozambique. In East Africa you can find a wide range of traditional vegetables in markets, supermarkets and restaurants and in addition to being harvested in the wild, many of these plants are cultivated in household gardens. However kale and rape are also beginning to dominate in these countries and nutritionists and agricultural researchers are trying to encourage a diversification back to the traditional super vegetables which are highly nutritious and better suited to the African climates according to research published by Elewa.org.
With malnutrition and climate change threatening, super vegetables should be part of Zimbabwean gardens of the future.