Sweet potatoes to let you see in the dark

Sweet potatoes are a staple food in many parts of the world, particularly in hot climates where they grow well. There are white-fleshed ones and orange-fleshed ones. The orange-fleshed ones help people’s eyesight.

Orange-fleshed sweet potatoes (OFSP) contain carotene. It makes them orange and it makes them good for eyes. Other parts of the body, too. Here’s how: when a person eats carotene, the body turns it into Vitamin A. That vitamin is essential for the eyes and for the immune system. If your mother told you to eat orange-coloured vegetables to let you see in the dark, she was talking about Vitamin A.

The World Health Organization says that 285 million people are visually impaired and 90% of those people live in developing countries. That’s partly because Vitamin A deficiency (VAD), and the eye problems it causes, are conditions of poverty.

VAD is one of the most common causes of childhood blindness. This starts early. The 1000 Days Movement tells us that Vitamin A is particularly important during pregnancy and early childhood. UNICEF agrees through its Childinfo website. There, UNICEF tells us that 33% of preschool-age children and 15% of pregnant women have VAD. UNICEF provides data to show that this is about poverty. Showing a map, UNICEF says, ‘The highest prevalence and numbers [of VAD] are found among countries of sub-Saharan Africa and South East Asia.’

Here comes the heroic sweet potato (Ipomoea batatas). Three weeks ago I wrote about Helen Keller International, a non-governmental organisation devoted to preventing blindness and reducing malnutrition. One of its strategies is to promote OFSP. Here’s some science about OFSP improving young kids’ Vitamin A status concluding, ‘Consumption of OFSP improves vitamin A status and can play a significant role in developing countries as a viable long-term food-based strategy for controlling vitamin A deficiency in children.’

All About Sweet Potatoes tells us the history and origin of I. batatas. This is a nutritious vegetable which is important in many countries. Let me tell you that I. batatas isn’t a yam. It’s known as ‘yam’ in some parts of North America, but from a botanist’s point of view, it’s dramatically different from the true yam (Dioscorea macrostachya and other species in that large genus). Here’s a history of how the names became confused. I. batatas isn’t a potato, either – the true potato is Solanum tuberosum.

All very interesting but the sites I’ve just linked to don’t mention what’s special about OFSP. For that, you might want to look at the International Potato Center (called CIP, its Spanish acronym). CIP takes a worldwide view and tells us how all kinds of roots and tubers can improve poor people’s lives. Here’s what CIP says about I. batatas.

I. batatas can let you see in the dark, if you eat the orange-fleshed kind. OFSP promotions are working in sub-Saharan Africa. Here’s a film about OFSP in Tanzania. Here’s another film about OFSP in Ghana.

But many poor people, hence many people with VAD, live outside Africa. Eating OFSP is surely needed in Asia. CIP is responding to the Asian need. ‘Approximately 45 percent of the world’s… children and pregnant women [with VAD] live in South and Southeast Asia… the use of [OFSP] in Asia to combat VAD is not yet as advanced as it is in Africa, [but] CIP is introducing varieties that are rich in Vitamin A along with successful outreach programs promoting their consumption.’

So the selectively bred OFSP is being promoted in Africa and, increasingly, in Asia too. In Asia it has to compete for market share with a biotech product, genetically modified Golden Rice (GR). My fellow blogger Janina at Food (Policy) for Thought has an open mind about GR and I too have an open mind.

The International Rice Research Institute (IRRI), based in the Philippines, promotes GR. In contrast Africa Rice, with offices in several sub-Saharan countries, doesn’t promote GR.

What I’m seeing is OFSP for Africa and GR for Asia. People grow and eat sweet potatoes in both of these continents; people grow and eat rice in both of these continents; people need more Vitamin A in both of these continents.

If you know why Africa is being offered Orange-Fleshed Sweet Potatoes to improve sight, whereas Asia is being offered Golden Rice, do please let me know.

[Edit] You might choose to watch the WordPress blog about the third African Rice Congress. Or go to that Congress, if you can. It’s to be held in October this year. I won’t be there but I’ll be watching.


About argylesock

I wrote a PhD about veterinary parasitology so that's the starting point for this blog. But I'm now branching out into other areas of biology and into popular science writing. I'll write here about science that happens in landscapes, particularly farmland, and about science involving interspecific interactions. Datasets and statistics get my attention. Exactly where this blog will lead? That's a journey that I'm on and I hope you'll come with me.
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10 Responses to Sweet potatoes to let you see in the dark

  1. EqFe says:

    The African climate doesn’t lend itself to growing rice, so there is no profit for a biotech firm to push GMO rice on Africa.

    • argylesock says:

      I wondered about that. But Africa is a large continent with several different climates. And there’s Africa Rice, implying that rice is grown on that continent. So I’d be glad to see evidence about whether there’d be ‘no profit’ for a firm promoting Golden Rice there.

  2. EqFe says:

    I can’t produce evidence that it can’t be grown on the continent, however I can’t find evidence that it’s actually grown in quantity. African rice is a different species grown in West Africa that is low yielding, some rice is grown in near the Niger river, and I found reference that most of the rice consumed in Africa is imported. As you point out it’s a big continent, with a lot of countries, but the reality is that most are two dry to grow rice. I found this article on African staple foods quite interesting.
    Let me reanswer you original question in a different way. Far greater quantities of rice are currently grown in Asia than in Africa making the potential market for yellow rice, especially in the short run greater in Asia

    • argylesock says:

      Thank you for this link. I’ve added the site (Afrol) to my list of ‘News Outlets’ here on this blog.

      It seems that rice is indeed grown as a staple food in parts of sub-Saharan Africa. But the site you linked to does say that most of the rice eaten in Africa is donated or imported. In fact, from that site, I now think that sweet potatoes are of local importance but not widely grown.

      Afrol says, ‘Today the principal food crops in the western part of the continent are cereals; millet, sorghum, rice and maize. Root crops such as manioc, cocoyams, sweet potato and yams are also important locally. Perennial cash crops include both groundnuts and soybeans. ‘

      I’m no expert on Africa or on Asia. Perhaps the range of OFSP and/or the range of GR could expand in both of those continents if people want it.

    • argylesock says:

      PS You might want to watch the African Rice Congress http://africaricecongress2013.wordpress.com/

  3. Pingback: Solutions for micronutrient deficiency | Science on the Land

  4. Pingback: Golden Rice is ‘no solution’ to malnutrition | Science on the Land

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