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Sweetpotato for Profit and Health Initiative

created by

Jan W. Low
International Potato Center

last modified Mar 10, 2011 02:43 PM
Launched in October 2009, the Sweetpotato Profit and Health Initiative is a 10-year, multi-donor effort that seeks to reduce child malnutrition and improve smallholder incomes through the effective production and expanded use of sweetpotatoes. By 2020, it aims to improve the lives of 10 million African households, achieving an annual value of $241 million in additional production in 17 African countries.

Achieving the vision of repositioning sweetpotatoes in the food economies of sub-Saharan Africa rests on three programmatic areas directed to reducing rural poverty and malnutrition on the continent.  These programmatic areas are defined in terms of development outcomes.  The first program focuses on positioning sweetpotato within the policy agenda and building capacity for effective research and development programs.  This program focuses on strengthening the evidence base and integrating sweetpotatoes into the policy agenda.  Markets and policy are considered to be mutually reinforcing elements and this area will support the creation of market demand through public awareness and advocacy programs, principally built around the food security benefits of the crop and nutritional benefits of orange-fleshed sweetpotato (OFSP).  Demand creation would also spillover into the policy area, but needs to be reinforced by building a stronger evidence base for the crop.  This would include increasing the policy visibility of sweetpotatoes through building a firmer and more reliable statistical base, incorporating sweetpotato data collection in standard consumer budget and farm surveys, and utilizing these to build a broader evidence base for the role that sweetpotato currently plays and will play  in national food systems.

 

The second programmatic area interacts closely with the first and focuses on combating Vitamin A and other nutritional deficiencies through the use of sweetpotato in food-based approaches.  Sweetpotatoes are in many ways the leading edge to the development of food-based nutritional approaches to reduce vitamin and mineral deficiencies in vulnerable groups, primarily young children and pregnant and lactating mothers.  Sweetpotatoes combine pro-Vitamin A—and potentially zinc—with carbohydrates as a nutrient dense food source for such vulnerable groups.  Food-based approaches to improving nutrition are considered to be more sustainable than alternative capsule distribution programs and can better target vulnerable groups in rural areas (where the problem is principally located) than fortification programs can do.  There is an increasing interest across a wide range of international NGO’s in integrating their health, nutritional, and agricultural programs in those rural areas with high poverty rates and Vitamin A deficiency.  The focus on the nutritional benefits of sweetpotato in turn has spillover into the perception of the commodity among urban populations in delivering health advantages.

 

These spillover effects then provide an entry point to repositioning sweetpotatoes in urban food consumption patterns, particularly in responding to a growing urban food market and further expanding market opportunities for sweetpotatoes.  African economies currently, and certainly compared to the situation at Independence, have large metropolitan areas that are growing very rapidly.  Domestic markets dwarf agricultural exports from the continent, creating market opportunities for smallholder producers, which has been given new impetus with the increase in price of grain imports.  These producers in turn must increase their sales, while maintaining their household food security, and given their scale of production, significant increases in productivity become the principal mechanism by which to achieve this.  Changing the image of sweetpotatoes toward a more preferred product, extending the supply period of the crop, increasing the efficiency of the marketing chain, and enhancing access to improved production technologies, are principal means by which to create a synergistic growth in supply and demand for sweetpotatoes, thereby contributing to increases in farmer incomes and potential reductions in rural poverty, particularly in high population density regions of the continent.

 


Program One:   Positioning sweetpotato within the policy agenda and building capacity for effective research and development programs 

The objective of this program is to increase the visibility and the image of sweetpotatoes in the minds of consumers, policymakers, and implementing agencies.  There is a marked degree of “invisibility” of sweetpotatoes in contrast to the relative importance of the crop in African food systems.  A range of factors contribute to this, particularly the fact that sweetpotatoes do not in general dominate in farming systems, the difficulty of collecting statistics given its short maturity, small area planted, and seasonality, and the secondary role that the crop plays in most urban food markets.  This results in unreliable statistics being generated for the crop and the tendency to aggregate those available under “other”.  Annual farm surveys often miss the crop, particularly if done at the end of the cereal harvest season.  In turn, few economic studies are done on the crop, reducing sweetpotatoes to the perceived rank of a minor crop.  There is a clear need to build a reliable statistical and evidence base for sweetpotatoes as a first step both to building a research community around the crop but also to give statistical expression to the importance of the crop in national food economies.

 

Reversing this “invisibility” will be based on three principal sub-programs, namely building the evidence base, public awareness and demand creation, and advocacy.  These three sub-programs naturally interact but each requires specific skills and strategies, many not often found in research and development institutions.  Building the evidence base requires both an understanding of the institutional contexts and methods employed in collecting basic statistics but also more advanced spatial methods—rather than population based approaches—in data collection.  Public awareness and demand creation involves methods for understanding consumer attitudes, developing strategies focused on behavior change, targeting messages, and understanding the use of alternative communication media.  Advocacy programs, on the other hand, focus more on influencing the policy agenda and ensuring that sweetpotato is incorporated into principal policy initiatives.  Advocacy programs must be evidence-based, and as such, build on a strong knowledge management program within the Initiative but at the same time incorporate an understanding of policy processes and participation in important policy events.

 

There will be a two-pronged approach to building an improved evidence base for the crop, firstly through improving the collection of sweetpotato statistics within existing data collection efforts and secondly through applying more advanced remote sensing techniques to the collection of sweetpotato statistics, including the design of spatial sampling methodologies.  The first approach builds on existing data collection efforts and builds sweetpotato data collection procedures into these methods.  This will require interacting with central statistics bureaus and ministries of agriculture, and will involve interaction on the design of both basic supply and utilization statistics, as well as on incorporation of sweetpotatoes into both farm or household surveys and consumer budget surveys.  Because of the short maturity of sweetpotatoes and the potential for multiple crops, particularly in the bimodal rainfall areas, accurate survey and data collection is highly dependent on timing or well worked out recall methods.  Building a supply and utilization statistical base comparable with other crops will be critical to improved assessment of the crop’s importance and its incorporation in agricultural sector planning.

 

A potential complement to improved national data collection efforts is the use of remote sensing techniques to assess the area under sweetpotato.  The methods to do this have recently been worked out for a case study in Kamuli District in Uganda (Zorogastua et al. 2007).  The method employs high resolution SPOT images, ground truthing, and the identification of an area of the reflectance spectrum that is unique to sweetpotatoes.  The methodology provides not only an estimate of the production area (significantly underestimated in Uganda production statistics) but also spatial distribution of sweetpotato in the region.  This allows a number of possible applications, including integration of other spatial data layers allowing identification of agro-ecozones or correlations with other factors determining distribution, design of spatial sampling frames for surveys and monitoring and evaluation systems, and targeting of field based activities.  Combining the spatial distribution with more sweetpotato specific surveys will provide a framework for building a coherent evidence base for the crop and linking it to other data collection programs.

 

The demand creation and public awareness sub-program is a central activity within the integrated development of OFSP, particularly in terms of maximizing its nutritional benefits through changing the habits of mothers’ feeding of their young children.  Understanding current attitudes towards sweetpotatoes and their role in food consumption patterns in the household is critical to designing communication programs to change behavior and to targeting of messages for particular population strata.  Designing messages, employing different communication media to reach vulnerable populations—particularly the increasing role of local, vernacular radio-- and coordination with access to vines and production techniques, are core components of a public awareness program focused on maximizing the nutritional impacts of OFSP.  However, the larger task will be to build on this work to change the image of sweetpotatoes in urban markets and among urban consumers.  This will involve re-branding of sweetpotatoes, primarily through the health advantages of OFSP varieties or the substitution of a significant proportion of wheat flour in processed products.  The other strategy is to focus on changing urban food consumption practices—e.g. the substitution of boiled sweetpotato for bread at breakfast or use of sweetpotato to produce chips.  Sweetpotatoes offers an interesting coordination issue for public awareness programs in targeting of production messages to farmers, nutritional messages to vulnerable households, and consumption messages for the urban consumer at the same time that it reinforces sweetpotato-based field programs undertaken in both nutrition and production technologies.

 

The third activity undertaken in this sub-program is that of advocacy to position sweetpotatoes more centrally in the policy and planning process.  As compared to public awareness, effective advocacy rests on independent research and the accumulation of an evidence and knowledge base.  Knowledge management becomes a critical component of the activity but effectiveness will depend on matching the message often delivered in policy briefs or presentations to opportunities at national, sub-regional, and continental levels.  Such effectiveness depends on maintaining some intelligence on “high impact” meetings, policy planning processes, and institutions where sweetpotatoes should be part of their work on agriculture, health, or nutrition.  This may involve the creation of a network of sweetpotato “champions” who can argue for sweetpotatoes in national policy processes.  It will also involve the development of best practice standards in the execution of OFSP nutritional programs among the expanding number of institutions implementing OFSP projects.

 

Program Two: Combating Vitamin A and other nutritional deficiencies through the use of sweetpotatoes in food-based approaches

Because of the very high levels of childhood malnutrition on the continent, the high prevalence of HIV in a large number of countries, particularly in Southern Africa, and the close correspondence between nutrition and overall health status, nutritional programs have assumed a much larger profile in health ministries and with NGO’s involved in livelihoods and community development.  Activities to reduce micronutrient malnutrition, especially among young children and pregnant and lactating mothers, have involved two principal approaches.  The first is supplements, such as Vitamin A capsules, principally dispersed through medical clinics.  These programs tend to be organized as campaigns and do not provide continuity of access and as well have limitations in terms of coverage.  The alternative approach has been fortification of frequently consumed foods with micronutrients limited in the diet.  These are very effective in addressing nutritional problems in households who primarily purchase their food, but these tend to be urban populations, whereas the populations with the high prevalence of undernutrition are in the rural areas, primarily among households who do not have large food purchases.  The alternative to these two strategies are food-based approaches, where households grow and consume crops that provide the requisite vitamins and micronutrients.  The problem with these approaches is the limited number of crops with a sufficient complement of these nutrients that can also be effectively utilized in the body, i.e. are bioavailable.  Horticultural crops and most recently OFSP have been utilized in such food-based approaches.

 

Orange-fleshed sweetpotato as a staple food has an advantage over most vegetables in that it can supply significant amounts of vitamin A and energy simultaneously – thus helping to address both VAD and undernutrition. OFSP is an example of a biofortified crop in which the micronutrient status of staple foods is enhanced through plant breeding to the point where impact on micronutrient status can be achieved (Bouis 2002).  Since the poorest households typically obtained over 60% of their energy needs from food staples, this strategy is particularly suited to poor rural households that cannot access purchased fortified food products but could grow OFSP.

 

Compelling evidence is available of the potential contribution of OFSP to improved nutrition. To evaluate potential health and economic impact, economists estimate the number of vitamin A deficiency (VAD)-related Disability-Adjusted Life Years (DALYs) that could potentially be saved through the use of biofortified sweetpotato.  Results indicate that just by replacing white-fleshed with orange-fleshed varieties the VAD burden could be reduced by 15 to 22% in 17 SSA countries where sweetpotato is widely grown (Stein et al. 2005; Fuglie and Yanggen 2007). Ex-ante analysis determined that if OFSPs were adopted by one-in-six Ugandan households within 10 years of becoming available, the effort would achieve an estimated internal rate of return between 16 and 30 percent and yield a net present value between $23 million and $67 million (Fuglie and Yanggen 2007).

 

The focus of program two is thus on utilizing OFSP as a model for food-based approaches (utilizing a crop with a visible trait) for reducing malnutrition in vulnerable groups in Africa.  A test of this approach in Mozambique demonstrated significant increases in vitamin A intake and a 15% reduction in prevalence of low serum retinol (a proxy for vitamin A status) in young children in spite of the poor health environment (Low et al. 2007).  A recent survey identified 59 projects utilizing OFSP in nutritional programs across sub-Saharan Africa, suggesting a momentum developing toward food-based approaches, as well as the deployment of OFSP as a model crop for such programs (Low et al. 2009).  As such, sweetpotato is the first biofortified crop in use at farmer and household level.  However, this is still very early stages in the widespread deployment of OFSP. Deepening the nutritional impacts across the range of agro-ecologies, the variation in child health status, the differences in institutional contexts for deployment, and the spectrum of market systems for the crop, will require different varieties and different delivery systems adapted to local contexts.  An evaluation of programs implemented across these different environments will lead to the development of best practice in implementation of OFSP in nutritional programs to reach desired target groups.

 

Program two will be built around four principal objectives, namely: (1) Developing orange-fleshed varieties with the other required agronomic and consumer traits required for incorporation in local farming systems and food economies; (2) Increasing the level retention and bioavailability of micronutrients in OFSP, including cooked, stored, and processed forms; (3) Maximizing the nutritional impact of OFSP with complementary health interventions, including people living with AIDS; and (4) Identifying cost-effective models for scaling out integrated production, nutritional, and market programs using OFSP.  The research program spans work on technology components, particularly an expanding range of OFSP varieties and, within that, improving the associated levels of zinc and possibly iron; on increasing nutritional impact with complementary health interventions; and on testing implementation models for integrating agricultural, nutritional, and health programs to achieve maximal nutritional impacts in terms of both coverage and the ability to reach vulnerable groups.  This interacting combination of diagnostic research, station-based research, and “proof-of-concept” research reflects a research program very much oriented toward achieving impact, developing the institutional or deployment models to do so, and adapting to different agro-ecological, institutional, and market conditions as coverage is expanded.

 

Much of the increase in breeding effort on the continent, both through the enhanced capacity in national breeding programs and in the pre-breeding activities to be carried out in the sub-regional platforms, will be focused on combining other priority traits with enhanced beta-carotene content.  Two particular breeding projects are felt to be essential.  Firstly is breeding OFSP varieties with drought tolerance, particularly to better target those areas with the highest prevalence of VAD.  Secondly is increasing dry matter (DM) content in OFSP varieties.  East, Central and West Africa have preferences for roots with higher dry matter than is currently found in existing OFSP varieties.  However, current breeding populations suggest a negative correlation between beta-carotene and dry matter.  Breaking this genetic linkage through the pre-breeding work will be a principal focus of the work in both West Africa and East and Central Africa.  Developing an enhanced pipeline of improved OFSP varieties with a range of other traits will be the base on which to scale out food-based approaches using OFSP.

 

Additionally there is a positive correlation in the sweetpotato germplasm between beta-carotene, iron, and zinc.  If included as a selection criterion in breeding programs, average levels of iron and zinc in OFSP could be expected to double within the next five years.  Iron and zinc deficiency are the other two widespread micronutrient deficiencies in the world with their deficiencies associated with increased susceptibility to infection, impaired growth, anorexia, and impaired cognitive function. Iron deficient anemia is estimated to affect over 1 billion people worldwide (Hess et al. 2005). Clearly, if the three micronutrients could be enhanced simultaneously, this would significantly expand the nutritional impacts from using sweetpotatoes in food-based nutritional programs. 

 

The last two components of the strategy of using OFSP in food-based approaches focus on linking agricultural programs based on OFSP with programs in the health and education sectors to better target vulnerable groups in the population.  Much of this work will focus on links to health programs that attempt to reach young children, pregnant and lactating mothers, and persons living with HIV/AIDS (PLWH).  There is the expectation that health programs such as deworming, diarrhea control, and malaria prevention will have an additive effect on nutritional interventions and the overall impact on health status of vulnerable groups.  Increasing vitamin A intake is only part of the solution; health interventions are essential to improve the absorption of vitamin A and other micronutrients in the body.  The challenge is to find the most effective entry points in reaching vulnerable households and specific target groups and which have the best chance for sustained adoption and widespread impact in short, medium, and longer-term interventions.

 

Targeting PLWH populations have particular requirements.  HIV leads to the establishment of an increasingly vicious cycle, with food insecurity (reduced access and increased need) heightening susceptibility to HIV exposure and infection, and HIV in turn heightening vulnerability to food insecurity.  At the same time, food intake is an increasingly recognized factor for highly active anti-retroviral treatment (HAART) tolerance and adherence (The World Bank 2007).  While not all wasting among PLWH is caused by lack of food, qualitative and quantitative studies of the needs of people being treated in resource-poor settings often list food as one of their greatest needs (Au et al. 2006; Mshana et al. 2006).  The goal of nutrition support for PLWH in need of ART is to stabilize nutritional status prior to and during treatment, help people regain strength, and contribute to improving nutritional status during treatment. In places where food insecurity prevents people from accessing or adhering to treatment regimes, food programs can play an important role in increasing uptake and adherence to treatment (Megazzini et al. 2006).  The extent to which OFSP can meaningfully contribute to PLWH affected households, and whether the best way of reaching them is through programs specifically targeted at HIV/AIDS affected households or just targeting poor rural and peri-urban households in general are questions that must be addressed to maximize the impact of OFSP on PLWH.

 

Scaling-out of any intervention is always a challenge, but in the case of OFSP the integrated nature of the intervention provides an additional challenge as nutrition/health interventions have typically been treated institutionally as separate initiatives from agricultural interventions. Moreover, marketing and finance components require an additional set of skills. The key question is whether scaling-out a fully integrated approach can be done cost-effectively. A major study, known as the Reaching End Users project, is currently underway in Uganda and Mozambique to scale-out an OFSP-focused intervention in agriculture, nutrition, and market development. The intervention was designed to use village-level promoters to supplement extension personnel as a means for reaching a larger number of households.  Results from this study (due in 2010) will provide insights as to what is the intensity of contact that is needed and what it will cost to succeed in integrating OFSP into the household farming system and into the young child diet.  However, this is only one among a range of possible delivery mechanisms.  Other principal delivery approaches are to link OFSP more explicitly to health delivery programs and to integrate OFSP into school feeding programs.  This component of the strategy focuses on understanding cost-effective delivery through alternative institutional frameworks.

 

 

Program Three:  Responding to a growing urban food market and further expanding market opportunities for sweetpotatoes

African food economies are at a transitional stage in their development as urban markets are growing rapidly and are reaching significant size relative to just meeting rural consumption requirements.  Satisfying urban food needs into the future will require shifts in farming systems to generating higher levels of marketable surpluses, significant increases in the efficiency of food marketing systems, and investment in food processing and agro-industry.  These needs have led to some consideration of larger-farm approaches to commercializing the sector, but most countries see the need for basing agricultural growth on development of smallholder agriculture, which can meet complementary goals of reducing rural poverty and improving the welfare of women.  Moreover, agricultural economies in Africa are now showing signs of responding to the structural adjustment and market liberalization programs of the 1990’s, particularly in terms of increasing private sector investment in agriculture.  Nevertheless, market systems for both inputs and outputs, particularly as they are based on servicing smallholder farmers, remain highly underdeveloped and inefficient.  This puts commodities like sweetpotato at something of a competitive disadvantage, given the bulkiness and perishability in marketing fresh roots.  Yet, with the increasing prices of grain imports, policies are increasingly focusing on production of domestic staples, such as root crops.  Both the policy environment and the structural changes taking place in African food economies offer opportunities for expanding markets for sweetpotatoes.

 

Developing more robust sweetpotato markets in African food economies will require modifying the structural constraints currently impeding the development of sweetpotato markets.  These are interacting constraints and include localized production in dispersed production zones (making assembly and bulking quite costly), seasonal supply of a bulky and perishable product limiting development of consistent consumption patterns, and high transaction costs and marketing margins.  These result in relatively thin markets, marked price variability, and low urban consumption as fresh roots.  Resolving these issues will require working across the value chain from production to consumption.  The strategy to do this will involve three principal interacting components, namely extending the supply period from seasonal to continuous supply, improving the efficiency in marketing of fresh roots, and developing new products with changed demand characteristics.  The latter will involve a range of components very much adapted to the food economies of the three sub-regions.  Particularly, these will include demand creation through re-branding of sweetpotato on the basis of the health advantages of OFSP, development of non-sweet, high dry matter sweetpotato roots as a “tropical potato”, development of processed products especially as a substitute for wheat flour, and development of on-farm feeding systems based on either forage or dual-purpose varieties.

 

Developing continuity of supply during the whole year will involve a range of elements, including staggered planting so that crops will not all mature simultaneously, developing a menu of varieties with different maturities and abilities to store in the ground, in ground storage of roots after maturity for up to six months, and seed production systems that provide vine supply during most of the year. These adaptations in the production system could be married with adjustments in the marketing system whereby different production ecologies supply roots for principal markets at different periods of the year.  There would still be some seasonal variation in prices to motivate both the increased production costs and the competition with other crops in off season production ecologies, but the continuity of supply would provide a basis for changing consumption patterns by incorporating sweetpotatoes into the diet during the whole year.

 

Continuity of supply could also be an entry point for improving the efficiency in marketing of fresh roots, particularly as thin and seasonal markets limit the potential gains to collective action.  Collective action by farmers has been promoted as a means of reducing transaction costs in assembly, particularly in achieving a cost-effective volume (namely a lorry load), and of attaining bargaining power in market transactions. In areas of commercial production for urban markets, such as exist in Uganda, either local traders organize the assembly and transport or traders based in urban markets come to the production areas, often doing the harvesting.  Traders based in production areas have an advantage in organizing collective action around assembly but must rely on brokers in urban markets to break down the lorry load.  Traders based in urban markets have better market intelligence and networks of retailers but are less efficient in assembly.  Achieving a more effective division of labor and coordination through the fresh root value chain will allow greater efficiencies and lower marketing margins.  This will be facilitated by further investments in road networks and improved market infrastructure, which are occurring in many African countries.

 

The largest gains to expanding demand are, however, expected to occur in the area of re-branding of the commodity and expanding different uses of the crop.  As a new product in urban markets, OFSP has unique visual and health attributes for consumers which offer potential for brand identification. This could be reinforced by supplying markets with higher quality roots and possibly grading.  Introducing OFSP varieties as a stand-alone agricultural intervention has limited potential for success. Rather, introduction must be associated with adjustments through the value chain, driven by awareness and demand creation associated with improved health status for consumers. If demand can be created for a high quality product, there is potential for a price premium emerging compared to white fleshed sweetpotato, further motivating farmer adoption of OFSP varieties.

 

Demand creation should look for particular market entry points. It could start with nutrition education in school feeding programs or with changing product perceptions at the high end of the market, through promotion in supermarkets which are rapidly expanding in cities in SSA.  The latter option is being tested in Kenya and Tanzania, combined with supplies of indigenous African vegetables, both of which focus on improved nutrition.  This promotion as a vegetable among high-income consumers has the potential to spill over into urban markets supplied through the traditional wholesale markets.  In Mozambique, painted market stalls, signs on buildings, decorated cloth for women, radio programs, community theater, and training traders to market OFSP, were employed to create awareness of OFSP’s nutritional qualities and increase demand for the commodity.

 

A similar strategy will be pursued in West Africa through the development of non-sweet, high dry matter “poundable” varieties, potentially with a range of beta-carotene contents.  This product will target both substitution for the expanding use of Solanum potatoes among urban West African consumers (the tropical potato) and expanding sweetpotato use in more traditional consumption forms for root crops, namely gari, fufu, and other steamed or boiled product forms.  The latter will compete with cassava, yam, and plantain, but the expectation is that this is where the largest growth in root crop demand will come in the future and sweetpotato adds diversity to the traditional root crop consumption forms. 

 

The final strategic component in this program targets the “value revolution” in African urban food consumption patterns.  The increasing consumption of income-elastic commodities encompasses primarily horticulture and animal products.  Some root product forms of sweetpotato, particularly emphasizing the health aspects, are targeting the expanding vegetable markets in African cities.  However, another significant market is to use sweetpotato as an animal feed in on-farm feeding systems.  The focus here is on better integration of sweetpotatoes into crop-livestock systems for smallholders, particularly the intensification of livestock production in the smallholder farming systems in the East African highlands.  The focus will be on the use of forage varieties to replace or complement Napier grass in smallholder dairy systems.  Sweetpotato vines are more productive than Napier, particularly with the recent outbreak of the stunt disease on the grass in East Africa.   A complementary activity will be to assess the potential of dual-purpose varieties in smallholder pig production systems, especially drawing on the experience with these systems in Asia, and particularly the use of silage systems.

 

 

Citations

 

Au, J. T., K. Kayitenkore, E. Shutes, E. Karita, P. J. Peters, A. Tichacek and S. A. Allen (2006). "Access to adequate nutrition is a major potential obstacle to antiretroviral adherence among HIV infected individuals in Rwanda. AIDS 20(16): 2116-2118.

 

Bouis, H. (2002). "A new tool for fighting micronutrient malnutrition." Journal of Nutrition 132 (Symposium: Plant breeding): 491S-494S.

 

Fuglie, K. and D. Yanggen (2007). Impact of sweetpotato biofortification on vitamin A deficiency in developing countries:  an ex-ante economic assessment. Manuscript. Lima, Peru, International Potato Center (CIP).

 

Hess, S. Y., D. I. Thurnham and R. F. Hurrell (2005). Influence of provitamin A carotenoids on iron, zinc, and vitamin A status. Washington D.C., International Food Policy Research Institute (IFPRI) and the International Center for Tropical Agriculture (CIAT).

 

Low, J. W., M. Arimond, N. Osman, B. Cunguara, F. Zano and D. Tschirley (2007). "A food-based approach introducing orange-fleshed sweet potatoes increased vitamin A intake and serum retinol concentrations in young children in rural Mozambique." Journal of Nutrition 137: 1320-1327.

 

Low, J. W., R. Kapinga, D. Cole, C. Loechl, J. Lynam and M. Andrade (2009).  “Nutritional Impact with Orange-fleshed Sweetpotato.” Chapter 3 in  Andrade, M., I. Barker, D. Cole, H. Dapaah, H. Elliott, S. Fuentes, W. Grüneberg, R. Kapinga, J. Kroschel, R. Labarta, B. Lemaga, C. Loechl, J. Low, J. Lynam , R. Mwanga, O. Ortiz, A. Oswald and G. Thiele (2009). “Unleashing the potential of sweetpotato in Sub-Saharan Africa: Current challenges and way forward.” Working Paper 2009-1. Lima, Peru, International Potato Center (CIP): 200 p.

 

Megazzini, K., S. Washington, M. Sinkala, S. Lawson-Marriott, E. Stringer, D. Krebs, J. Levy, B. Chi, R. Cantrell, I. Zulu, L. Mulenga and J. Stringer (2006). “A pilot randomized trial of nutritional supplementation in food insecure patients receiving antiretroviral therapy (ART) in Zambia.” XVI International AIDS Conference. Toronto, Canada, August 13-18, 2006, Abstract MoAb0401.

 

Mshana, G. H., J. Wamoyi, J. Busza, B. Zaba, J. Changalucha, S. Kaluvya and M. Urassa. (2006). "Barriers to accessing antiretroviral therapy in Kisesa, Tanzania: a qualitative study of early rural referrals to the national program." AIDS Patient Care STDS 20(9): 649-657.

 

Stein, A. J., J. V. Meenakshi, M. Qaim, P. Nestel, H. P. S. Sachdev and Z. A. Butta (2005). Analyzing the health benefits of biofortified staple crops by means of the disability-adjusted life-years approach:  a handbook focusing on iron, zinc, and vitamin A. Washington D.C. and Cali, International Food Policy Research Institute (IFPRI) and the International Center for Tropical Agriculture (CIAT).

 

The World Bank (2007). HIV/AIDS, nutrition, and food security: what we can do.  A synthesis of international guidance. Washington D.C., USA, The International Bank for Reconstruction and Development (The World Bank).

 

Zorogastúa, P., R. Quiroz, M. Potts, S. Namanda, V. Mares and L. Claessens (2007). “Utilization of high-resolution satellite images to improve the statistics of sweetpotato cultivated area in the district of Kumi in Uganda.” Working Paper 2007-5.  International Potato Center (CIP), Lima, Peru. 14 p.

 

 

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