**1. Introduction**

Hidden hunger has become a major development issue, especially in developing countries. The concept refers to a situation where households and individuals may have access to food

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 include the nutritional content of the food.

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 labeled as the food security crops [2].

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

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 by 13–15%.

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, evidence on the factors that drive adoption of OFSP remains very limited. At the same time, no study has systematically examined the effect of awareness of the nutritional benefits of OFSP and household food security status on early adoption OFSP varieties in the presence of the more popular white-fleshed varieties. This chapter uses the multivariate probit regression technique to control for the effects of competing interests in the planting of different varieties of sweetpotato by including the more popular local (white-fleshed) varieties. The chapter then tests two hypotheses. The null hypothesis tested in the two cases state that participation in the project (a proxy for awareness of benefits of OFSP) and food insecurity (a proxy for poor households) have no effect on the decision to plant the sweetpotato varieties examined in this study.

That is, it first tests the hypothesis that the likelihood of adopting OFSP is affected by food insecurity status of the households. Second, the chapter tests the hypothesis that awareness of the nutritional benefits of the OFSP increases the likelihood of planting OFSP.

The chapter focuses on smallholder farm households in the four regions of Tanzania, namely, Mara, Mwanza, Shinyanga, and Kagera. The households are stratified by participation in a project known as Marando Bora, which, among other things, sensitized farmers on nutritional benefits of consuming OFSP varieties. The Tanzania project provides an interesting case study because of the high incidence of poverty in the study regions and activities of the project that created awareness about the importance of growing OFSP and of consuming diets rich in vitamin A to combat vitamin A deficiency.

The rest of this chapter is organized as follows: Section 2 provides the study background and describes the Marando project. Section 3 outlines the study methods while Section 4 presents and discusses the results. Lastly, Section 5 concludes and highlights key policy implications.
