**2. Study background**

in sufficient amounts but fail to attain the required quantities of micronutrients. These micronutrients include zinc, iron, and vitamin A. Hidden hunger is especially a major problem among poor rural households who cannot afford purchased supplements. The problem of hidden hunger, first coined in the 1990s, led to greater emphasis on defining food security to

The inability of households to afford purchased food supplements required to meet micronutrient needs has led to the rethinking of the strategies to improve access to essential micronutrients. One approach that has gained importance is the biofortification of crops most frequently used by poor/rural households [1]. Hence, the last one decade has witnessed concerted efforts to breed for crops that have enhanced quantities of essential micronutrients. Some of the essential nutrients targeted by these efforts are zinc, iron, and vitamin A. The crops targeted by these efforts include sweetpotato, maize, sorghum, beans, and cassava. These staple crops are consumed by a large number of rural households in developing countries and are often

Sub-Saharan Africa (SSA) has one of the largest number of food insecure households. Global hunger index (For details, see http://www.ifpri.org/pressrelease/global-hunger-index-callsgreater-resilience-building-efforts-boost-food-and-nutrition-) developed by the International Food Policy Research Institute ranked this region among those with highest levels of hunger. The high incidence of hunger results from inadequate intakes of both micro and macronutrients needed by the body to function adequately. Foremost among the micronutrients that are contributing to micronutrient-based food insecurity in SSA is vitamin A [3–5]. Prevalence of vitamin A deficiency (VAD) is high among the East African countries, including Ethiopia, Uganda, Rwanda, Kenya, and Tanzania [6]. High incidence of VAD is also reported in Southern African countries such as Zambia, Malawi, and Mozambique. For instance, vitamin D deficiency in Uganda is estimated to be about one-third of the population. In Kenya, about

To combat VAD among these countries, the consultative group for International Agricultural Research (CGIAR) has focused biofortification efforts on maize, sweetpotato, and cassava. Among these, the greatest investment, and success, has been in the development of vitamin A rich orange-fleshed sweetpotato (OFSP). These efforts have been recognized by the award of the 2016 World Food Price to biofortification of sweetpotato. At the same time, past studies have found increased intakes among rural women and children [4, 5] and evidence of reduced incidence of VAD among these vulnerable groups [9]. These studies further suggest regular consumption of OFSP can reduce VAD among vulnerable groups

Theoretically, the increased intake of OFSP should, in turn, result in higher adoption of OFSP varieties. To date, however, evidence regarding early adoption of OFSP varieties in SSA remains mixed, with experts (i.e., scientists) predicting much higher adoption than what empirical studies suggest [10]. At the same time, there is still rather limited presence of OFSP in the local markets even where extensive campaigns have occurred. This chapter draws from a rich dataset collected from 732 households and the multivariate regression technique to assess the factors that influence a farmer's decision to grow/adopt OFSP varieties. To date,

include the nutritional content of the food.

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labeled as the food security crops [2].

70% of pre-school children suffer from VAD [7, 8].

by 13–15%.

## **2.1. The concept of food insecurity and food-based approach to fighting micronutrient deficiency**

Food security has been defined variously in the literature. However, the most widely used definition of food security is that of [11]. It states that food security is "a situation that exists when all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food that meets their dietary needs and food preferences for an active and healthy life." Among the pillars emphasized by this definition is the fact that food needs to meet nutritional requirements of the people. The failure to access food that meets the nutritional needs of the household, also known as hidden hunger, is, therefore, one of the subtle yet equally dangerous forms of food insecurity. It specifically arises when households do not have access to a diverse diet that supplies their micronutrient needs.

A new strategy being used to combat hidden hunger among poor rural households is the promotion of production and consumption of biofortified crops that are bred to supply the essential micronutrients. This strategy, often referred to as the food-based approach to enhancing household nutrition, particularly aims at tapping into the local food production system to tackle the problem of poor or inadequate consumption of foods that supply essential nutrients. The strategy uses the locally produced staple foods to introduce essential micronutrients into the locally available and preferred foods.

One of the micronutrients targeted by this strategy is vitamin A. Vitamin A deficiency (VAD) is widespread in many rural communities of Africa. It is especially prevalent among pregnant or lactating women and children who are less than five years of age. Young children need vitamin A to fight common childhood diseases (e.g., diarrhea) and for healthy growth. Pregnant women, on the other hand, are in greatest need for vitamin A during the third trimester when they and the unborn child have the highest demand for vitamin A. Thus inadequate consumption of vitamin A–rich foods by these vulnerable household members can significantly compromise the development of the child and health of the mother. Thus growing and consuming vitamin A–rich crops can act as a vehicle for tackling VAD. Indeed, proof-concept studies and efficacy trials have demonstrated that consumption of modest amounts (125g a day) of orange-fleshed sweetpotato (OFSP), a biofortified crop, can supply the daily needs of vitamin A [1, 12, 13].

Following the findings of past studies, several countries have intensified efforts to promote the growing and consumption of biofortified sweetpotato varieties (i.e., orange-fleshed varieties that are rich in vitamin A). The countries include Ethiopia, Kenya, Uganda, Tanzania, Zambia, and Mozambique. Promotion of the varieties usually includes provision of clean planting material to farmers at subsidized rates along with information about the nutritional benefits of growing and consuming orange-fleshed sweetpotato (OFSP). These efforts usually target the farming households and enable them to grow vitamin A–rich foods.

#### **2.2. The case for sweetpotato production in Tanzania and benefit awareness**

Sweetpotato is an important food security crop in many districts of Tanzania, including the Lake Victoria region. Throughout these districts, it helps bridge the hunger gap often characterized by acute shortage of staple foods. There are several reasons why sweetpotato plays a significant role in bridging the hunger gap among sweetpotato producing communities. First, sweetpotato can stay in the soil for an extended period making it easy for farmers to "store" it in the field and harvest piecemeal or as needed. Second, it can withstand moisture stress caused by lack or insufficient rains hence it fills in the food gap during inclement weather. Third, sweet potato does not require much use of external inputs and is often grown without fertilizers and pesticides.

Until recently, farmers planted mainly the white and yellow-fleshed varieties of sweetpotato. These varieties contribute to household food security by providing starch (sugars) needed to supply body energy. They, however, lack (for the case of white-fleshed varieties) or contain inadequate amounts of the beta-carotene, the precursor for vitamin A. Nonetheless, the majority of households grow these non-OFSP varieties to meet household food/subsistence needs. Varieties that are richer in vitamin A, popularly known as the orange-fleshed sweetpotato, due to the deep orange color of the flesh, have been bred for the dual purpose of supplying household energy (starch) and micronutrient needs.

The study targeted Tanzania because of the high incidence of poverty among the rural farm households [14] leading to poor nutritional intake hence inability to access purchased food supplements needed to remedy the vitamin A deficiency. Tanzania also has one of the world's highest rates of undernutrition [1]. It is estimated that around 2.4 million children in Tanzania are malnourished and that 42% of children suffer from stunting. The authors [1] further indicate that about one-third of children in Tanzania are deficient vitamin A. The Tanzania Food and Nutrition Center (2012) estimated that vitamin A deficiency would contribute to one out of 10 child deaths between 2006 and 2015.

household nutrition, particularly aims at tapping into the local food production system to tackle the problem of poor or inadequate consumption of foods that supply essential nutrients. The strategy uses the locally produced staple foods to introduce essential micronutrients

One of the micronutrients targeted by this strategy is vitamin A. Vitamin A deficiency (VAD) is widespread in many rural communities of Africa. It is especially prevalent among pregnant or lactating women and children who are less than five years of age. Young children need vitamin A to fight common childhood diseases (e.g., diarrhea) and for healthy growth. Pregnant women, on the other hand, are in greatest need for vitamin A during the third trimester when they and the unborn child have the highest demand for vitamin A. Thus inadequate consumption of vitamin A–rich foods by these vulnerable household members can significantly compromise the development of the child and health of the mother. Thus growing and consuming vitamin A–rich crops can act as a vehicle for tackling VAD. Indeed, proof-concept studies and efficacy trials have demonstrated that consumption of modest amounts (125g a day) of orange-fleshed sweetpotato (OFSP), a biofortified crop, can supply

Following the findings of past studies, several countries have intensified efforts to promote the growing and consumption of biofortified sweetpotato varieties (i.e., orange-fleshed varieties that are rich in vitamin A). The countries include Ethiopia, Kenya, Uganda, Tanzania, Zambia, and Mozambique. Promotion of the varieties usually includes provision of clean planting material to farmers at subsidized rates along with information about the nutritional benefits of growing and consuming orange-fleshed sweetpotato (OFSP). These efforts usually

Sweetpotato is an important food security crop in many districts of Tanzania, including the Lake Victoria region. Throughout these districts, it helps bridge the hunger gap often characterized by acute shortage of staple foods. There are several reasons why sweetpotato plays a significant role in bridging the hunger gap among sweetpotato producing communities. First, sweetpotato can stay in the soil for an extended period making it easy for farmers to "store" it in the field and harvest piecemeal or as needed. Second, it can withstand moisture stress caused by lack or insufficient rains hence it fills in the food gap during inclement weather. Third, sweet potato does not require much use of external inputs and is often grown without fertilizers and pesticides.

Until recently, farmers planted mainly the white and yellow-fleshed varieties of sweetpotato. These varieties contribute to household food security by providing starch (sugars) needed to supply body energy. They, however, lack (for the case of white-fleshed varieties) or contain inadequate amounts of the beta-carotene, the precursor for vitamin A. Nonetheless, the majority of households grow these non-OFSP varieties to meet household food/subsistence needs. Varieties that are richer in vitamin A, popularly known as the orange-fleshed sweetpotato, due to the deep orange color of the flesh, have been bred for the dual purpose of

target the farming households and enable them to grow vitamin A–rich foods.

**2.2. The case for sweetpotato production in Tanzania and benefit awareness**

supplying household energy (starch) and micronutrient needs.

into the locally available and preferred foods.

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the daily needs of vitamin A [1, 12, 13].

The intervention in Tanzania through a project known as Marando Bora, a Swahili phrase for better quality vines, was launched in 2009. The Marando Bora project specifically focused on promoting the use of clean/quality sweetpotato planting materials. It was aimed at resolving the clean seed bottleneck by developing and testing effective strategies for multiplication, dissemination, and exchange of disease-free (i.e., clean/quality) vines from which new plants can be propagated. The project was implemented in several districts of the Lake Victoria region of Tanzania. The project used two strategies to reach out to farmers namely decentralized vine multipliers (DVM) and mass distribution (MD). Under the DVM model, 88 trained vine multipliers were provided with quality planting materials to bulk. Farmers were then informed about these multipliers and given information about where to find them. The MD model used open-air meetings, conducted by partner nongovernmental organizations and government extension personnel, to create awareness among farmers about quality vines.

The Marando Bora project expanded to cover four regions of Tanzania. An estimated 110,000 households were reached through the project between 1999 and 2012. The regions the project has covered are Mara, Mwanza, Shinyanga, and Kagera (**Figure 1**). These regions fall the drier

**Figure 1.** A map of the southern region of Tanzania showing the study areas. *Source*: http://www.mapsofworld.com/ tanzania/tanzania-political-map.htm.

agroecological zones namely zone P4, zone P5, zone P8, zone W3, and zone N10. The sensitization on the use of quality planting materials focused on the sweetpotato agronomy, pest and disease diagnosis, and protection and methods for conserving vines for future planting.
