How sweet potato can help achieve a win-win diet

by Jan Low | International Potato Center
Friday, 7 June 2019 09:40 GMT

ARCHIVE PHOTO: Malawian subsistence farmer Rozaria Hamiton plants sweet potatoes near the capital Lilongwe, Malawi February 1, 2016. REUTERS/Mike Hutchings

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* Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.

There is no doubt in my mind that sweet potato is going to be part of the healthy, sustainable diet solution in the tropics and sub-tropics

As the momentum for global climate action grows, there is increasing scrutiny on the part played by our food choices. 

landmark report, published earlier this year by the EAT-Lancet Commission, sets out the need for a global diet that meets two criteria: both healthy for the consumer and sustainable for the planet.

The report offers guidelines on how much of each food group would nourish us sufficiently while also minimising the environmental impact of food production.

But one under-appreciated and under-utilised food crop not mentioned explicitly in these guidelines - but which is already vital to many developing countries where both food choices and food production are limited - is sweet potato. 

In sub-Saharan Africa, it is a widely grown root crop, covering around 4.5 million hectares – an area roughly equivalent to Denmark - and producing 30.2 million tons of roots in 2016.

Its resilience in the face of water scarcity and higher temperatures makes it a crop that can continue to feed families even when others fail. It is also one of the few tropical crops that can grow from sea level to 2,400 meters, making it viable in all of sub-Saharan Africa’s eco-regions except the desert.

And thanks to innovative research and development, the sweet potato is only getting better as a sustainable staple, providing more nutrients for consumers with less time, land and resources.

Firstly, in terms of nutrition, all types of sweet potato have good amounts of vitamins C, K, E, and several B vitamins along with manganese and phosphorus. But orange-fleshed varieties are extremely rich in beta-carotene, which the body converts into vitamin A.

Just 125 grams of this orange-fleshed sweet potato can provide the recommended daily allowance of vitamin A for children. Given that vitamin A deficiency affects 48 per cent of children under five years of age in sub-Saharan Africa, the rationale for promoting this variety is clear. 

Secondly, sweet potato can be the basis for a sustainable diet because it provides more calories per hectare and per growing month than all the major grain crops, which is especially important in the face of growing competition for land and resources.

Early-maturing types can be harvested in just three months while also growing alongside grains and legumes on marginal land. These qualities continue to make sweet potato a viable crop despite changing temperatures and climate.

Thirdly, sustainable food systems also need to maximize the use of crops grown locally, not only to reduce the environmental impact of food production but to reduce the cost as well. In 2016 alone, countries in sub-Saharan Africa spent US$4.1 billion importing wheat. 

Clearly, the call to move towards more sustainable diets is a sensible one. But the nutritious diet needed in sub-Saharan Africa will be different than that for the global north, as many nutritional deficiencies urgently need to be addressed.

Often called a “superfood” by health-conscious consumers with the luxury of choice and access, the most important aspect of sweet potato is it that it is easy to grow and is affordable for consumers. There is no doubt in my mind that sweet potato is going to be part of the healthy, sustainable diet solution in the tropics and sub-tropics.