The contribution of orange-fleshed sweet potatoes towards nutrition security in rural areas in Mwanza, Tanzania

Bachelor Thesis, 2011

105 Pages, Grade: 1,3


Table of contents

List of Abbreviations

List of Figures

List of Tables


1 Introduction

2 The United Republic of Tanzania
2.1 Geographic data
2.2 Demographic data
2.3 Economy and government

3 The Tanzania Home Economics Association
3.1 Work of the organization
3.2 Overview of Projects

4 Influences of the nutritional situation in Tanzania
4.1 Traditional diet
4.2 Food and Nutrition security
4.3 Malnutrition ̶ effects and causes

5 Vitamin A ̶ an example of nutrition disorder
5.1 Absorption and storage
5.2 Function
5.3 Aspects of dosage
5.3.1 Deficiency effects and symptoms
5.3.2 Toxicity

6 Sweet potato ̶ a solving approach for nutrition disorder
6.1 Agricultural facts
6.2 Cultivation and storage problems
6.3 Physiological function
6.4 Processing methods and effects

7 Empirical Research
7.1 Empirical question and hypothesis
7.2 Research design
7.2.1 Survey methodology 24-hours recall Supporting observations
7.2.2 Evaluation methodology
7.3 Results of the survey
7.3.1 Results of self-conducted 24-hours recall
7.3.2 Results of 24-hours recall of foreign study
7.3.3 Results of supporting observations
7.4 Discussion and conclusion

8 Summary




List of Abbreviations

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List of Figures

Fig. 1: Undernourishment by world-region (in millions)

Fig. 2: Map of Tanzania

Fig. 3: Map of Mwanza region

Fig. 4: The pillars of food and nutrition security

Fig. 5: Prevalence of malnutrition per type among preschool children in sub-Saharan Africa

Fig. 6: Vitamin A metabolism

Fig. 7: Varieties of OFSP

Fig. 8: Major sweet potato producing areas in Tanzania

Fig. 9 : Sweet potato production per capita in ten selected countries (in tones per million)

Fig. 10: Phases of empirical surveys

Fig. 11: Schedule of a participant observation

Fig. 12: Percentage of age groups

Fig. 13: Consummated varieties

Fig. 14: Cultivated varieties at household level

Fig. 15: Consumption and sales of sweet potatoes per bag (25kg)

List of Tables

Tab. 1: Short-form of recipe for Eat Orange-cookery training

Tab. 2: Prudent upper levels of habitual vitamin A intake

Tab. 3: Natural variability in beta-carotene content of raw medium-sized OFSP, variety Resisto, from same harvest batch

Tab. 4: Nutrient Composition of OFSP, Cassava and Maize

Tab. 5: Laboratory results of nutrient-content of different types of flour

Tab. 6: Overview of hypotheses, variables, and expressions of the


Tab. 7: Estimated size of portions in grams

Tab. 8: Recommendation for human daily nutrient intake

Tab. 9: Average nutrient intake per person per meal - Mwasonge

Tab. 10: Average nutrient intake per person during whole day - Mwasonge

Tab. 11: Average nutrient intake per person per meal - Tunyenye

Tab. 12: Average nutrient intake per person during whole day - Tunyenye

Tab. 13: Comparison of the coverage of nutritional recommendations


Particularly in developing countries nearly one billion people are effected by nutrition insecurity in form of under- or malnutrition (FAO 2010, p. 1). Merely by the expression of vitamin A-deficiency an estimate of up to 500,000 children go blind worldwide every year (WHO 2011). This bachelor thesis deals with a solution approach in form of the contribution made by the orange-fleshed sweet potato (OFSP) and its afford towards nutrition security in rural areas of Mwanza, Tanzania. With help of the partner organization TAHEA, a retrospective population-based study of the nutritional status of rural population of Mwanza was conducted and impressions on food security were reinforced through participant observation. The positive influence of OFSP towards vitamin A status has been confirmed and among others an income-generating function by cultivation and sale of the tuber has been observed. The risk of a possible overdose must also be considered. Thus, the tuber is recommended as a nutritious snack or side dish, but should not be advertised as a considered staple food.

Aktuell sind besonders in Entwicklungsländern nahezu eine Milliarde Menschen von Ernährungsunsicherheit in Form von Unter- oder Mangelernährung betroffen (FAO 2010, p. 1). Allein durch die Ausprägung eines Vitamin A-Mangels, erblinden Schätzungen zufolge weltweit jährlich bis zu 500.000 Kinder (WHO 2011). Diese Bachelorarbeit beschäftigt sich mit einem Lösungsansatz in Form des Beitrags, den die orange-fleischige Süßkartoffel (OFSP) zur Ernährungssicherheit in ländlichen Gebieten von Mwanza, Tansania, leistet und leisten kann. Mit Hilfe der Partnerorganisation TAHEA wurde durch eine retrospektive Stichproben-Studie der Ernährungszustand der ländlichen Bevölkerung Mwanzas erfasst und Eindrücke zum Thema Ernährungssicherheit durch teilnehmende Beobachtungen untermauert. Der positive Einfluss der OFSP auf die Vitamin A-Versorgung wurde bestätigt und unter anderem eine einkommensbildende Funktion durch Kultivierung und Verkauf der Knolle beobachtet. Doch auch die Gefahr einer möglichen Überdosierung muss beachtet werden. Somit empfiehlt sich die Knolle als nährstoffreiche Zwischenmahlzeit oder Beilage, sollte aber nicht als täglich zu verzehrendes Grundnahrungsmittel beworben werden.

1 Introduction

"Food and nutrition security exists when all people, at all time, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active, productive and healthy life"

(WFS 1996, p. 3).

This bachelor thesis is the result of a three-months project in the United Republic of Tanzania1 carried out with the support and help of the local organization Tanzania Home Economics Association (TAHEA). It deals with the contribution of orange-fleshed sweet potatoes (OFSP) towards nutrition security in rural areas in Mwanza, Tanzania. TAHEA wants to make an assessment about the success of their conducted sweet potato projects especially for the rural living part of their project participants and develop on the basis of the outcome possible improvements to food security and education. The survey was planned on behalf of the organization and performed with their help.

The beginning of modern interest in food security is coincident with the Second World War, which demonstrated that localized hunger, resulting undernourishment and instability could escalate into problems of global significance (MCDONALD 2010, p. 12). In 1996 the WORLD FOOD SUMMIT requires in its Rome Declaration on World Food Security that each nation must adopt a strategy consistent with its resources and capacities to achieve its individual goals and cooperate regionally and internationally in order to organize cooperative solutions to global issues of food security and health (WFS 1996, p. 3).

Worldwide, actually nearly one billion people are classified as undernourished, most of whom live in the developing countries (see Fig. 1). There, they account for 16 percent of the population (FAO 2010, p. 1). Malnutrition is also highly prevalent in Tanzania. More than a third of children below five years are affected by chronic malnutrition, also called stunting, and in the southern zone prevalence surpasses about 50 percent (FAO 2008, p. 3). A special form of malnutrition is vitamin A deficiency (VAD), which is a serious wide spread nutritional and health problem affecting a lot of people especially children in the developing countries including Tanzania. Most countries in the sub-Saharan 1 In the following text the country is written as "Tanzania" for the sake of readability. This always means the United Republic of Tanzania.

region are categorized as having a public health problem concerning clinical and nonclinical VAD. Of the global total of 140 million children affected by VAD, nearly 100 million live in South Asia or sub-Saharan Africa (SSA) (Mason et al. 2001, p. 34).

Fig. 1: Undernourishment by world-region (in millions)

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(modified from FAO 2010, p. 2)

The poor population of developing countries has only limited access to expansive foods that contain high values of vitamin A, like liver, milk and butter. Significant efforts has therefore been made to support improved vitamin A intake through increased dietary intake and improved storage and preparation of a variety of appropriate plant sources that contain this vitamin (LOW et al. 2001, p. 4). One of that special promoted plant sources is the sweet potato. New varieties rich in beta-carotene were introduced through a research institute, adding health value to the existing varieties (TAHEA 2009, p. 2) to secure food and nutrition security.

This survey shall now illuminate the daily consumption of rural population to represent the proportion of the sweet potato roots to nutritional intake particularly in view to vitamin A to prevent deficiency. In this way it is to observe whether the cultivation of OFSP has changed or even improved the everyday lives of cultivars and consumer in health and economic manner. To set these possible aspects of the contribution of OFSP towards nutrition security into context with existing scientific findings, the issue shall be considered theoretically, but also be represented by a self-conducted empirical survey. The theoretical foundations shall be represent a basis of which the own survey can be evaluated and assessed in its results.

In conclusion, these considerations lead to the following objectives of this work:

- Survey of eating habits of Tanzanian people (especially rural living) to control the supply of nutrients
- Determining the extent of OFSP-cultivation and -consumption and potential positive impact on health of the population
- Survey of the processing methods at household level including the hygienic conditions
- Determining the contribution of OFSP and products made of it to the income generation of farmers and their families.

To achieve these goals also for the self-conducted survey, the methods of a nutrition survey in the form of a 24-hours recall and additional participant observations were chosen and performed in a rural village located in a district of Mwanza that is supported by TAHEA and its projects. As a comparison, the data of a 24-hours recall carried out in the same period by DWOJACZNY (2011) in a village without special support are used. This village is also part of a rural district of Mwanza. It is to find out if these people also consume OFSP or know about beneficial effects of this variety without special teaching. This shall also show whether the promotion and support of the sweet potatoes offers desired impact and benefits for the population.

2 The United Republic of Tanzania

2.1 Geographic data

With an area of about 945,000 square kilometers (km²), Tanzania is the largest of the East African countries (UNESCO 2007, p. 3). About 62,000 km2 of the main land is covered with water (GOVERNMENT OF TANZANIA 2011). Since 1964, the country is the union of two countries – Tanzania mainland (namely Tanganyika) and Zanzibar (UNESCO 2007, p. 3) – and is now divided into 26 regions. Tanzania is located south of the equator between 1° and 12° south latitude and 29° and 40° east longitude. Tanzania borders with Burundi, Democratic Republic of the Congo, illustration not visible in this excerpt (see Fig. 2).

Fig. 2: Map of Tanzania

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Mwanza is located in the northern part of Tanzania, directly at the coast of the Lake Victoria (THE UNITED REPUBLIC OF TANZANIA 1997, p. 1) (see Fig. 3). The region is divided into seven administrative districts, namely Gaita, Kwimba, Magu, Misungwi, Mwanza Town, Sengerema, and Ukerewe (THE UNITED REPUBLIC OF TANZANIA 1997, p. 3f.). The region has a total area of about 35,000 km2, of which 20,000 km2 are dry land and 15,000 km2 are covered with water. Land wise, Mwanza is the fourth smallest region after Dar es Salaam, Kilimanjaro and Mtwara (MSEKELA 2008, p. 2).

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Fig. 3: Map of Mwanza region

Tanzania is exposed to climate hazards such as droughts and floods, and to natural disasters resulting from earthquakes, making it vulnerable to the ensuing climate change brought about by global warming (UNESCO 2007, p. 3). The Temperatures and rainfalls of Mwanza region are influenced by proximity to Lake Victoria and Equator. The maximum temperature is about 26 °C during June to August (MSEKELA 2008, p. 3) while the standard annual rainfall of Mwanza region is about 930 millimeter (mm) unreliable from 1,800 mm in the western parts of Ukerewe island to 750 mm per square meters in the southern and south eastern parts of the region. Under usual conditions the rainfall is distributed mainly during two periods, namely the short rains in October to December and the long rains from March to May. There is a dry spell from January to March and regularly these rains are of an erratic pattern. The rain tends to fall limited to a small area storms rather than in a widespread downpour and so may be unequally distributed in quite a small area. Water erosion tends to increase with the length of the dry season and the weaker vegetation cover (THE UNITED REPUBLIC OF TANZANIA 1997, p. 23).

A large part of the country is covered with grasslands (40 percent) and scattered forest areas (47 percent), but the infestation by tsetse flies, making the country over wide areas unsuitable for livestock and human settlement. Agricultural available are five percent of the country, seven percent are other landforms (CIA 2011). The soils of Mwanza region are classified into sandy soils, red loams and black clays. Most of the population live in areas with sandy soils that have only moderate natural fertility and steadily deteriorate under conditions of continuous cultivation. The loam and clay soils are of higher potential but tend to be found in areas of low rainfall (THE UNITED REPUBLIC OF TANZANIA 1997, p. 23).

2.2 Demographic data

Actually Tanzania has a population of about 42 million people with a population growth rate of two percent per year. The median age of all inhabitants is 18.5 years (CIA 2011). The age structure of the country is defined as follows:

- zero to 14 years: 42 percent
- 15 to 64 years: 55.1 percent
- 65 years and over: 2.9 percent (CIA 2011)

The population of the Mwanza region is estimated to be 3.5 million people with a population density of 150 people per km2. With about 18.6 percent, Mwanza has the third highest level of urbanization of its population after Dar es Salaam (89.6 percent) and Morogoro (21.1 percent) (MSEKELA 2008, p. 2f.).

There are close to 120 tribal groups in Tanzania, including with relatively small but economically significant numbers of Asians and Arabs, and a small European community. The population of the mainland consists of 95 percent from Bantu peoples, including the Sukuma (13 percent of overall population that live around Mwanza and southern Lake Victoria), the Nyamwezi (around Tabora), the Makonde (southeastern Tanzania), the Haya (around Bukoba) and the Chagga (around Mount Kilimanjaro). The religious groups are divided into two large groups: The Muslims, who account for about 40 percent of the population, and about 45 percent of Christians. The remaining group of population follows traditional religious centre on ancestor worship, the land and different ritual objects. There are also some small communities of Hindus, Sikhs and Ismailis (NIEHAUSMEIER 2011).

The majority of the population lives in rural areas although urbanization has increased in the last three decades. Life expectancy, actually 46 years on average, has decreased in the past 20 years, possibly due to the increasing auto immune deficiency syndrome (AIDS) and human immunodeficiency virus (HIV) prevalence, which affects around seven percent of the adult population. 80 percent of the population has physical access to health services, but user fees and poor quality of services, mainly due to lack of expert health personnel, reduce the effectiveness of the health system. Poor sanitation settings are common both in the rural and urban areas, while access to safe water is a problem mainly for rural populations (FAO 2008, p. 3).

2.3 Economy and government

In 1961 the mainland of Tanganyika became independent while Zanzibar gained it in 1963 from the United Kingdom-administered trusteeship. In 1964 both united to form the United Republic of Tanzania. Since that date, the ruling party is the Chama Cha Mapinduzi or CCM, also called revolutionary party, under the current president of Jakaya Kikwete. The official capital is Dodoma (CIA 2011).

Tanzania is one of the world's poorest economies in terms of per capita income, although, the gross domestic product (GDP) growth about seven percent per year between 2000 and 2008 due to strong gold production and tourism. The country is endowed with important land and water resources that have a high agricultural potential. That is why agriculture is a key sector of Tanzania’s economy, accounting for 45 percent of GDP and is the source of livelihood for more than three-quarters of the population (FAO 2008, p. 3). It provides 85 percent of exports, and employs about 80 percent of the work force. Actually the GDP income per capita is 1,400 United States-Dollars (CIA 2011). In rural areas approximately 40 percent of the population are below the basic needs poverty line, while in the urban areas roughly a quarter of the population is poor (FAO 2008, p. 3). The access to financial services by these poor people has been limited due to number of reasons, like the poor infrastructure in the very rural and marginalized areas, where traditional microfinance institutions are unable to extend services to the inhabitants (SMFEA 2010, p. 4).

The main exports include coffee, gold, cashew nuts, cotton and handicraft (GOVERNMENT OF TANZANIA 2011). The main industry of the country is the agricultural processing of sugar, beer, cigarettes, and sisal twine. Other industries produce shoes, apparel, wood products, and fertilizer and there are some oil refineries. There are also big resources in salt, soda ash, and cement (CIA 2011).

The economy in Mwanza is dominated by smallholder agriculture. It is employing about 85 percent of the region’s population and next to the expanding fisheries sector. Mining and livestock sectors also command a recognizable share in the economy of the region. Mwanza is the primary producer region of the major cash crop cotton. In most cases the region is unable to feed itself due to constant droughts (MSEKELA 2008, p. 3f.). The people living in the Lake region suffer from the environmental problems affecting the Lake Victoria. Between 1998 and 2004 the water level of the 68. 800 km2 Lake has fallen by 2.3 meters. Reasons are at once the high power of turbine in water works, which Uganda operates, and on the other hand, rising temperatures and associated evaporation. Another problem is the rapidly multiplying water hyacinth, which makes it difficult for ships to move in the water, and is an excellent breeding ground of bilharzia-causing snails and malaria-causing mosquito. Decaying plant parts of hyacinth can decrease the oxygen content of the lake, threatening and cause fish kills. Here, the former fish wealth has been decimated anyway, since it has been exposed in the 1950s the Nile perch in Lake Victoria (KUErschner-Pelkmann 2007).

3 The Tanzania Home Economics Association

3.1 Work of the organization

TAHEA was founded in March 1980 as a national non-governmental organization (NGO) in Mwanza, Tanzania, (TAHEA w. y.). In 1992 it was decentralized into Tanzanian regions (GDN 2009). Asia Kapande was the founder and is currently the president of the organization. She manages the office in Mwanza, has implemented numerous projects in Tanzania and also holds positions in the government (GPN 2010). The mission and primary goal of the organization is to promote the improvement of quality of life of families, particularly of women (GDN 2009).

Originally founded by 17 members, the membership had expanded to over 1,000 members by the year 2000. There are several categories of membership; individual members of home economist and specialists in related fields like nutrition, agriculture, environment, and also teachers with agriculture home economics specialization. Other categories, for example, are an industrial or group membership (TAHEA w. y.). So with this wide range of associations, the number of members is rising constantly.

The Vision of TAHEA is written as "TAHEA wishes to see a society which is democratic and just, with improved living conditions, sufficient in food and a strong economic base" (CHALE 2011). The organization strives to empower individuals, families and the entire community in Tanzania, socially, economically and also with gender perspective through education, training, information and consultancy. They are going to realize their plan with the expertise of their professional members, by networking and also collaborating with other organizations that have similar visions and mission (TAHEA w. y.).

The current activities of TAHEA are to organize seminars and workshops for its members and also to run projects like to prevent acquired AIDS and infections with the HIV and control and counseling education. A major topic, TAHEA is working on, is food and nutrition in combination with health and disease topics. Some of the areas of action are the household food security and technology transfer, family life education, resource management and consumer protection. TAHEA is also active in fields like water quality, rural health and environment, family poverty alleviation, economic empowerment and fund raising (TAHEA w. y.).

3.2 Overview of Projects

There is a variety of projects that are supported and carried out by TAHEA (TAHEA w. y.), so here is taken a selection of thematically related projects.

Community Managed Microfinance

The basis for all projects of TAHEA is to build a Community Managed Microfinance-project (CMMF). This is a concept of microfinance within poor and hard-to-reach communities that involve mobilizing people, in particular women, to form self help groups, train this groups in group dynamics, record writing, access to community savings and credit so as to eventually link them to the better services for their social and economic advancement (SMFEA 2010, p. 2).

CMMF is based on the concept of the self help groups where members in a given community with a common cause are mobilized into self-selected groups of 15 to 30 individuals. Members are encouraged to save periodically and lend to themselves in order to engage in income generating activities. Members of these groups are also able to identify challenges within their communities and find appropriate solutions to address them. The money is paid back with interest, causing the fund to grow. The regular savings contributions to the group are deposited with an end date in mind for distribution of all or part of the total funds (including interest earnings) to the individual members, usually on the basis of a formula that links payout to the amount saved (SMFEA 2010, p. 5).

The loans allow the members to meet their small, short-term financial needs for income generating activities, social obligations and emergencies without having to borrow from a money lender, take an expensive supplier advance, or relying on their relatives. The household capacities are enhanced to access, control and manage their assets and to strengthen their coping and resilience mechanisms to achieve sustainable livelihoods (SMFEA 2010, p. 5). TAHEA is establishing this project in communities in Mwanza and its districts to prepare them for all future activities.

Jatropha Agriculture and Nutrition Initiative

The Jatropha Agriculture and Nutrition Initiative (JANI) was founded in 2006 as a multi-sectoral initiative by the United States Department of Agriculture (USDA) (PFD 2009). With local government support, TAHEA established the JANI-project as an implementing partner in the Lake Victoria Zone where they extended the activities to communities in the Misungwi district (PFD w. y.).

They provide small-holder farmers the technical support and training in order to increase household incomes and employment through sustainable cultivation of Jatropha and the sale of its products. They also improve food security and nutrition through sustainable vegetable and livestock production and strengthened capacity of local organizations to meet member´s needs (PFD 2009).

The JANI-project targets rural households in areas with good potential for economic Jatropha production. The objectives of the project are to establish and husband the Jatropha and also to establish market linkages with buyers of the products. The local processing includes village level oil extraction and soap making and also domestic energy utilization for lighting and cooking. It is also possible to incorporate Jatropha seed cake as fertilizer for sustainable production of nutritious foods, especially vegetables and local poultry (PFD 2009).

The advantages of Jatropha are their drought resistance and ability to grow under a variety of climatic and management conditions. The high oil content of the plant is able to replace imported fuel for diesel engines and domestic lighting. The surplus materials of the plants can be used as fire material for household cooking and protect the tree stock in this way. The oil of the Jatropha plant is also used in creams and soaps to treat skin diseases and represent also a good option for financial income generation (PFD w. y.)

Orange Fleshed Sweet Potatoes

TAHEA has been promoting sweet potato production for income generation and household food security since the year 2001. Since 2006, the organization has been implementing the projects "Scaling Up Sweet Potato Production" and "Eat Orange" including OFSP-varieties (TAHEA 2009, p. 2) as a response to the international project "Vitamin A for Africa" (VITAA). Consumption of OFSP with high levels of beta-carotene has been found to improve vitamin A status of school children and thus considered to be viable long term strategy for controlling VAD in areas where this deficiency is a problem (MULOKOZI et al. 2007, p. 28f.).

The overall VITAA-initiative was launched in 2001 as the first food-based initiative to attack the problems of VAD throughout in SSA, since in the entire area about 640,000 children die each year from causes associated with this deficiency. The partnership is dedicated to alleviating the suffering caused by VAD using OFSP that meet African standards for taste and texture. The VITAA initiative is aimed at making OFSP available on a large scale, demonstrating the potential of crop-based approaches in alleviating micronutrient deficiencies. VITAA member countries include Tanzania, Uganda, Kenya, Ethiopia, Mozambique, South Africa, and Ghana (ANDERSON et al. 2007, p. 711).

The concern of the Scaling up project is to form producer marketing groups who will receive new OFSP planting materials for rapid multiplication and to train the farmers on sweet potato crop husbandry practices. It is also planned to train the farmers and their families on sweet potato processing and marketing skills and also to link these people to local, district and regional markets where they can sell their own sweet potato products (TAHEA 2010, p. 8f.). Micro finance activities are introduced as a synergy to the project with the aim of improving the farmers access to financial support within their communities, at the same time building their capacity to accumulate their own capital. These activities also facilitate spending of their income from sweet potatoes as they always plan to spend the income they get from shares in sweet potato activities, school payment and livelihood household expenses. That shall bring more success to the implementing farmer groups in all districts (TAHEA 2010, p. 2).

The Eat Orange-project aimed directly at consumers at the household level. During multi-day cooking courses, project participants learn to cook different meals using sweet potato recipes. These recipes are divided into main courses, snacks and beverages (see Tab. 1). Especially the snacks can be sold and thus serve the security of income. The sweet potatoes grown in the village itself and other readily available ingredients are used. People are encouraged to increase their sweet potato consumption so that they can vary their diet. Also, hygienic aspects, such as body and kitchen hygiene are discussed in this training to reach total nutrition security. The project attempts to bring to the people a knowledge of preparation methods with little nutrient loss.

Tab. 1: Short-form of recipe for Eat Orange-cookery training

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A photographic documentation of the CMMF and Eat Orange-projects is presented in Appendix I.

4 Influences of the nutritional situation in Tanzania

4.1 Traditional diet

The diet of the Tanzanian population is based on cereals, starchy roots with high fiber content and pulses in rural as well as in urban areas (FAO 2008, p. 17). Starchy foods provide almost three quarters of the total energy supply, despite the wide variety of food produced in Tanzania. Consumption of micronutrient dense foods such as animal products is low and subsequently micronutrient deficiencies are widespread (FAO 2008, p. 3). Especially among rural communities the frequency of vegetable consumption is high. There they are included in every meal, but generally quantities are small. Therefore, vegetables do not contribute significantly to nutrient intake. Fruits are not commonly consumed, as they are not considered as important by many adults. Maize is consumed as a staple in all regions of the country, but especially in urban regions. Other cereals, roots and tubers such as yams, millet and sweet potatoes are known but contribute less to the diet as they are less preferred than maize (FAO 2008, p. 17).

The country is separated into seven agro-ecological zones, each one having a main staple. Widespread staples are: plantain in north western tip and northern Tanzania; maize and some sorghum in the central and southern highlands zones; rice in the river basins of Kilombero, Rufiji and eastern zones; cassava in western and south eastern areas. In rural areas and among the low-income part of the urban inhabitants, the quantity of food consumed can be limited and meal regularity varies with the season. During the wet season food consumed may be limited to one meal per day, while two to three meals may be consumed during the dry or harvest season. Frequency of meat and milk consumption is extremely low, on average once a week, a month or even less (FAO 2008, p. 17).

The most common main dish is stiff porridge, called in the national language Kiswahili as ugali, made from maize flour, sorghum or cassava with water. It is eaten with a relish either made of vegetables, sardines, pulses or meat. Rice and various fish cooked in coconut oil are also preferred staples for people living in coastal communities. The introduction of various spices by the Arabs is highly evident in a popular coastal dish, namely pilau. It consists of rice spiced with curry, cinnamon, cloves, cumin, and hot peppers. Eggplant, tomatoes, beans, spinach and other greens, as well as maize are frequently eaten, many of these are grown in backyard gardens. Fried bananas, also called plantains, is a very popular local dish, while in the cities, Indian food is plentiful. All of this meals are usually eaten out of a large bowl that is shared by everyone at the table (FOOD BY COUNTRY 2011).

Tea is the most widely consumed beverage. It is classically taken throughout the day, often while socializing and visiting friends and family. Sweet fried rice cakes called vitumbua are commonly eaten with the tea in the mornings, or between meals as a snack. Chapatti, a fried flat bread, also served with tea, is a popular snack among all groups of age (FOOD BY COUNTRY 2011).

In the urban areas, food behaviors and dietary patterns have radically changed in the last decades, especially among the high-income group, partly due to trade liberalization and globalization. Energy dense foods and western-type fast foods have become eagerly obtainable on the market and their consumption has increased considerably. The dietary pattern has changed from a traditional diet high in carbohydrates and fiber to consumption of non-traditional processed foods, meat and alcohol (FAO 2008, p. 17).

4.2 Food and Nutrition security

In 2009, there were about 280,000 people in Tanzania in the food insecure category. Some reasons are the decline in food supplies and high prices, due to increasing transport costs across the country, intensified plant diseases in the Lake Victoria Zone and a new imposed policy for using acceptable fishing equipment in lakes, rivers, and on the coast at a time when stocks from previous harvest are running low. These factors have caused moderate food insecurity in Mwanza and some other regions (FEWS NET 2009, p. 1).

Tanzanian national efforts to enhance the quality of food and nutrition by considering important aspects such as availability of food, proper food preparation and preservation began immediately after independence in 1961 and were reinforced after the Arusha Declaration of 1967 (MOH 1992, p. i). The formation of the Tanzania Food and Nutrition Centre (TFNC) in 1973 was one of the major steps taken by the Government to improve nutrition status in the country (MOH 1992, p. 10). In 1996, the Rome Declaration on World Food Security and the WORLD FOOD SUMMIT (1996) Plan of Action defined food security as existing when all people around the world at all times have access to adequate, safe, nutritious food to maintain a healthy and active life (see p. 1). Health is one of the basic human rights that does not only imply a person´s state of being free from disease but also the state of being well physically, mentally and spiritually hence the ability to participate fully in the community developmental process (WHO w. y. quoted from MOH 1992, p. i). Linked through malnutrition, health is an undeniably aspect of food and nutrition security, like sustainable economic development, environment, and trade to. That makes food and nutrition security to a complex sustainable development issue (WHO 2011).

Food security includes physical and economic access to food that meets people´s dietary needs as well as their food preferences (WFS 1996, p. 3). These dietary needs are defined as the nutritional status which is the balance between the intake of nutrients by an organism and the expenditure of these in the processes of growth, reproduction, and health maintenance (UMWELTLEXIKON-ONLINE 2010). The requirements varies with the level of physical activity, age and gender and also with the weight, body size of a person and the climatic conditions of the living place (NATIONAL ACADEMY PRESS 1989, p. 30ff.)

Nutrition security is achieved when a household has secure access to food connected with a sanitary environment, adequate health services, and knowledgeable care to ensure a healthy life for all household members. The results of more productive and profitable agriculture or from enhanced growth in the broader economy are an improved food security at the household or individual levels and thus an input to a better quality of life. An individual’s ability to reach the full personal and economic potential depends to a large degree on the level of nutrition security (BENSON 2004, p. 9). As food security, nutrition security is defined at the household and the individual levels, but the determinants extend far beyond the control of the household itself. It is the concern of many more institutions, sectors, and other actors (BENSON 2004, p. 11).

Food and nutrition security is built on three pillars, namely food availability, food access, and food use including hygiene aspects (see Fig. 4). It is a complex sustainable development issue that is linked to health through malnutrition, but also to sustainable economic development, environment, and trade (WHO 2011).

Fig. 4: The pillars of food and nutrition security

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(modified from FAO 2011)

Food availability

The availability of food depends on factors like self food production or national production, stock security, trade, donations and food aids. The access to productive resources, such as soil and agricultural inputs, as well as the availability of food production knowledge and technologies also decide the availability of food. Food availability can be affected as a result by variations in the macro-economic and political situation and also by the regional climatic phenomena. Crises, like natural disasters and civil strife and war, can seriously disturb food production and the constancy of food supply (HU-BERLIN 2002, p. 9). Availability of food includes also the availability of pure, clean drinking water. According to UNICEF (2010), about 80 percent of the urban population in Tanzania used improved drinking-water sources in the year 2008. In rural areas only about 45 percent have access to clean water sources (UNICEF 2010).

Food access

Food production does not automatically equal food security. If food is in fields or in the markets, but people cannot afford to acquire it, then they are food insecure (BENSON 2004, p. 8). People must have sufficient access to the available foodstuffs and water, whether they grow their own food or buy it. Hunger and malnutrition are not always a consequence of the available quantity of food at the national or household level. Reasons for inadequate access to food could be, for example, low purchase power, undependable sources of income or high prices. Access to food requires also the physical access to infrastructures such as markets, marketing systems and transport potentials (HU-BERLIN 2010, p. 9f.).

At present the food access conditions have remained satisfactory at the national level. All markets across the country are supplied adequately with staple food commodities. But market-dependent households suffer from high food prices (FEWS NET 2011, p. 1), as the food price index rose by 15 percent between October 2010 and January 2011 – that is 29 percent above its level a year earlier (THE WORLD BANK 2011).

Food use and utilization

The knowledge of and attitudes towards production, storage, processing, domestic preparation and consumption is closely linked to the nutritionally adequate use of food. There is an interface between food insecurity, infections and illness as adequate physical conversion of food depends on the health status. This links the measurement of use and utilization with the access to basic health care and reproductive health. The capability of households to provide appropriate caring practices, for themselves and for the most susceptible in their family and community, can improve use and utilization. The usage of food is also influenced by consumption habits and socio-cultural background, like intra household distribution of food and mother-child feeding practices. Another aspect of food use and consumption is a safe environment, including sanitation and waste disposal, guaranteeing the supply and utilization of safe and uncontaminated food and drinking water (HU-BERLIN 2010, p. 10).

4.3 Malnutrition ̶ effects and causes

The types, magnitude and causes of food and nutrition problems are environment specific. Actually there is no single country in the world without problems of malnutrition. In Tanzania, as is the case with other developing countries especially in SSA, the major food and nutrition problem is that of under- and malnourishment (MOH 1992, p. 3).

The common words malnutrition and undernourishment are indeed often used in the same context but must be distinguished from each other. Malnutrition arises from deficiencies of specific nutrients or from diets based on unsuitable combinations or magnitude of foods, and it can also result from excess nutrient losses or utilization (SHATTY 2003). So it is not just understood in the result of inadequate food intake, it is also caused by the quality of the food being consumed, poor access to health services, poor sanitation, and in the case of young children, inappropriate feeding and care practices (LOW et al. 2008, p.10). Undernourishment on the other hand is caused primarily by an inadequate intake of dietary energy, regardless of whether any other specific nutrient is a limiting factor (SHATTY 2003).

Malnutrition among young children is on the rise in SSA. Overall, in Africa, prevalence is predictable to increase from 24 percent in 1990 to 27 percent in 2015. High rates of HIV/AIDS prevalence aggravate malnutrition. Hence in East Africa, where the HIV/AIDS effect is strong, the incidence of underweight individuals is predicted to be 25 percent higher in 2015 than in 1990 (The World Bank 2006, p. 246).

The causes can be analyzed at three main depths as immediate, underlying and basic causes. Immediate causes can be the inadequate food intake resulting from low feeding frequency with insufficient energy and other important nutrients. This problem mainly affects children´s nutrition. It is also possible that there are frequent diseases which increase the utilization of nutrients in the body especially energy and at the same time causing loss of appetite and thus intensifying the problem of inadequate feeding (MOH 1992, p. 8f.). Underlying causes occur when there is food insecurity at any level, for example at household, village or national level, caused by problems related to production, harvesting, preservation, processing, distribution, preparation and various uses of food. Also inadequate care for special groups, for example small children, pregnant and lactating women, the elderly and the sick and inadequate essential services such as health education, water, environmental sanitation, housing and clothing can has malnutrition as a result (MOH 1992, p. 9). The basic causes are a poor economic situation, for example at household, village and national level and also an inequitable distribution and utilization of services and other resources. Traditions and customs which affect negatively the state of nutrition particularly women and children can also have an effect of the health and nutrition status of the people. According to the analysis of the various causes of food and nutrition problems, it has been shown that their solutions require cooperation and coordination among various sectors concerned with socio-economic development in the country (MOH 1992, p. 9f.).

The manifest malnutrition occurs mainly as four types: Protein energy malnutrition (PEM), nutritional anemia, iodine deficiency disorders (IDD) and VAD (MOH 1992, p. 3f.) (see Fig. 5).

Protein Energy Malnutrition

PEM is the major manifestation and ranks high in importance in Tanzania. Children between the age of six months and three years and pregnant as well as lactating women are the groups which are highly affected by this problem (MOH 1992, p. 4). PEM is a condition arising from insufficient energy and protein intake, which is usually provoked by episodes of diarrhea and other infections (TFNC 2005, p. 4).

Fig. 5: Prevalence of malnutrition per type among preschool children in sub-Saharan Africa

illustration not visible in this excerpt

(modified from UNICEF 1998, p. 22)

In children PEM manifests in the form of low weight for age and height. If deficiency is severe, the child will suffer from kwashiorkor or marasmus or a combination of both, called marasmic kwashiorkor. The symptoms of a child suffering from kwashiorkor are for example physical and mental retardation and they display a low bodyweight usually between 60 and 80 percent of the normal weight for the age of a child (MOH 1992, p. 4f.). Some symptoms of a child suffering from marasmus are thinness and physical retardation, old age appearance with sharp eyes, loose skin which can easily be pulled out, as well as low bodyweight, below six percent of the normal weight in relation to the age of the child. Frequent crying and an extraordinary appetite are also typical. A child suffering from both ̶ kwashiorkor and marasmus ̶ shows some of the features and particularly acute low bodyweight below 60 percent of the normal weight, as well as swollen arms and legs (MOH 1992, p. 5). The distribution of PEM in Tanzania varies from one area to another and within the same region. At national level it is predictable that 44 percent of children below the age of five years are stunted, with 17 percent of them being severely stunted (TFNC 2005, p. 5).

Nutritional anemia

Nutritional anemia results from insufficient iron intake and food as well as prevalence of diseases especially malaria, worms and bilharzias. This problem is very common among pregnant women, children below five years of age and school children (MOH 1992, p. 6). For Tanzanian children below five years there was a national prevalence of anemia of about 72 percent reported in 2005. For pregnant women it was reported to be about 49 percent (TFNC 2006a).

Iodine deficiency disorders

The problem of IDD results from lack of iodine in the soil, and hence deficiency in plants and animals living in such areas. As a result, people who feed on food grown in such areas also suffer from iodine deficiency. Areas highly affected by iodine deficiency are those situated in the highlands and far from the ocean (MOH 1992, p.7). IDD is globally estimated to affect more than 1.6 billion people with about 150 million affected in Africa (TFNC 2006b).

Vitamin A deficiency

VAD is a public health problem in more of half of all countries, especially in Africa and South East Asia, and the most preventable cause of blindness. Worldwide, there is an estimated 250 million preschool children with a VAD and it is likely that in deficient areas a substantial proportion of pregnant women are vitamin A deficient. An estimated 250,000 to 500,000 children become blind every year due to VAD, half of them dying within twelve months (WHO 2011). In developing countries the main reasons are a diet that is chronically insufficient in vitamin A or parasitic intestinal diseases. If there is a deficiency for people that live in industrialized countries, VAD often causes in fat digestion and absorption disorders, or storage and transportation difficulties (HESEKER et al. 2010, p. 486).

Combating VAD is a major role for the subject of this essay (see p. 1f.) and the projects of TAHEA, therefore this point is discussed in focus in the following chapter.

5 Vitamin A ̶ an example of nutrition disorder

In Tanzania VAD is one of the major nutritional problems of public health significance, affecting mainly children and women of child-bearing age (TFNC 2006c, p. 1). Poor households typically cannot afford to consume the highly bioavailable animal foods on a regular basis. High rates of deficiency in the major micronutrients are common among poor populations that consume plant-based diets (LOEBENSTEIN et al. 2009, p. 368). The low intake of animal products, along with insufficient intake of fruit and vegetables are the main cause for VAD in Tanzania. The widespread poverty and the high financial cost of animal products limits the consumption. Plant sources of vitamin A are more affordable, but the availability from animal sources would be higher (FAO 2008, p. 35).

Vitamin A-supplementation as interventions have been implemented by the government to alleviate VAD. The first national program for prevention and control of VAD started in the year 1985. The program focused on two main interventions: Supplementation as a short-term measure, and support of production and consumption of vitamin A-rich foods as a long-term strategy. Control of infectious diseases and nutrition education were also adopted as compassionate measures (TFNC 2006c, p.1f.). In 2004, de-worming was integrated into vitamin A-supplementation in all districts of mainland Tanzania. Twice-yearly vitamin A supplementation coverage in the country has been over 90 percent on average since 2001 (TFNC 2006c, p. 3f.).

The preservation and consumption of Vitamin A rich foods is carried out by conducting training to extension workers at district level, then they disseminate the knowledge to the community. They are also demonstrate preservation of vitamin A rich foods which include construction and use of solar driers. Identification and advocacy in use of vitamin A rich foods like red palm oil, and OFSP is also a common strategy. Efforts in fortification food with vitamin A are being done to some foods such as sugar that have already been identified as potential vehicle for fortification of vitamin A (TFNC 2006c, p. 5).

5.1 Absorption and storage

Vitamin A is a fat-soluble nutrient that is used by human body in three active forms that are collectively known as the retinoids. The compounds are retinol, retinal and retinoic acid, also known as preformed vitamin A (INSEL et al. 2011, p. 391). A variety of carotenes and related compounds, known as carotenoids, can be cleaved oxidative to yield retinaldehyde, and hence retinol and retinoid acid. That is the reason why they are also known as pro-vitamin A carotenoids (GIBNEY et al. 2009, p. 134). Only the compounds that have all biological effects of the vitamin can be called vitamin A. These are retinol and several retinyl esters that can be converted into retinal and retinoic acid. The pro-vitamin A carotenoids are also included, mainly beta-carotene, alpha-carotene and beta-cryptoxanthin (HESEKER et al. 2010, p. 481).

The human body is able to convert retinol to retinal. Retinal can also re-form retinol or it can irreversible form retinoid acid. The interconvertible nature of retinol and retinal allows them to support all the activities of the vitamin A compounds (INSEL et al. 2011, p. 391).

Preformed vitamin A is concentrated only in a certain tissues of animal products in which the animal has metabolized the carotene contained in its food into vitamin A. Carotenes are found in green, yellow, and red fruits and vegetables, as well as in milk and milk products. The richest source by far is liver. In addition to their role as precursors of vitamin A, carotenoids have potentially antioxidant action, which is associated with a lower incidence of cancer and cardiovascular diseases (GIBNEY et al. 2009, p. 134f.). The yellow-orange pigment beta-carotene can be cleaved into two molecules of retinal, which has the highest potential vitamin A activity of the pro-vitamin A family (INSEL et al. 2011, p. 391).

Vitamin A is absorbed either in the form of its pro-vitamin (usually beta-carotene) from plant or in the form of retinyl esters from animal products (BIESALSKI et al. 2007, p. 136). Retinol is the form of transport as well as an intermediate in the metabolism of vitamin A and retinyl esters represent the storage forms (HESEKER et al. 2010, p. 481) (see Fig. 6). The liver stores more than 90 percent of the body´s vitamin A in the form of retinyl esters. The remainder is deposited in adipose tissue, lungs and kidneys. The liver releases retinol - carried by retinol-binding protein (RBP) - in just the right amounts to maintain normal retinol blood levels (INSEL et al. 2011, p. 392).

Fig. 6: Vitamin A metabolism

illustration not visible in this excerpt

(HESEKER et al. 2010, p. 482)

5.2 Function

The first function of vitamin A to be defined was in vision. Retinol is carried by the blood to the retina, the paper-thin tissues that line the back of the eye, where it is converted to retinal. In combination with the protein opsin, retinal forms the pigment called rhodopsin, which is abundant in rod cells and makes it possible to see in dim light (INSEL et al. 2011, p. 392). Vitamin A is also involved in color vision, as part of the pigment iodopsin in cone cells (INSEL et al. 201, p. 394).

Retinoic acid has shown to have a major function in regulation of gene expression and cell differentiation. In this process stem cells are developed into highly specific types of cells with unique functions (INSEL et al. 2011, p. 396). Retinoic acid interacts with nuclear receptors that bind to response elements of Desoxy-ribonucleinacid acid (DNA), and regulate the transcription of specific genes. They control the expression of genes that encode enzymes and structural proteins, growth factors, interleukins and cytokines. These are involved in the proliferation and differentiation of cells and tissues, for example the respiratory epithelium, intestinal mucosa, skin, tumor and embryonic cells (HESEKER et al. 2010, p. 483).

Vitamin A also influences the immune system in important ways, like in its support of thymic lymphocytes, which maintain the body´s ability to mount an immune response against infectious invaders (INSEL et al. 2011, p. 396). Spermatogenesis, oogenesis, placental development and embryogenesis are in all animals also retinol-dependent. Thus, vitamin A affects both male and female reproductive processes. Retinol supports sperm duct epithelium and sperm production, while it also, oxidized to retinoic acid, is needed for testosterone production. As part of embryogenesis retinoic acid is involved in the morphogenesis of various organs, such as eyes, ears and the central nervous system. The exact gene expression is still unclear (HESEKER et al. 2010, p. 483). Also, retinol, retinal, and retinoic acid are all essential for bone health and growth. As the reproductive processes, the exact mechanism is still unknown (INSEL et al. 2011, p. 396).

5.3 Aspects of dosage

The standard unit for quantifying the biologic activity of the various forms of vitamin A and its precursors is the retinol activity equivalent (RAE) (INSEL et al. 2011, p. 391). One milligram (mg) RAE is one mg retinol, six mg beta-carotene, or twelve mg of other pro-vitamin A-carotenoids. Approximately one mg retinol equivalent is 3,000 international Unit (IU) of vitamin A. For the analytical differentiation of vitamin A precursors and their assessment of the biological activity, the IU is the antiquated form of expression. These figures are strictly standardized for animal testing under standardized feeding conditions. For example is 0.3 microgram (μg) retinol is one IU vitamin A – an indication which is common for the conversion of isolated compounds with vitamin A character. With a mixed diet many of these substances are absorbed simultaneously, so that the demand and use is indicated in RAE (GIBNEY et al. 2009, p. 134).

By the NATIONAL ACADEMY OF SCIENCES (1989) a daily supply of 375 µg RAE is recommended for infants, for children from 400 to 1,000 µg RAE and for adults 800 (women) or 1,000 µg RAE (men). Lactating women are advised to intake an additional 400 to 500 µg RAE (NATIONAL ACADEMY OF SCIENCES 1989, p. 285).

5.3.1 Deficiency effects and symptoms

The earliest signs of clinical deficiency manifests at the eyes with a loss of sensitivity to green light, followed by an impairment of ability to see in dim light. The result is night blindness. Deficiency of sufficient duration or severity can lead to xerophthalmia (GIBNEY et al. 2009, p. 139) - a disease in which the eyeball loses luster, it becomes dry and inflamed, and visual acuity is reduced (LOW et al. 2008, p. 10). The keratinization of the cornea, followed by ulceration, is an irreversible damage to the eye that causes blindness (GIBNEY et al. 2009, p. 139). The skin is also changing, with excessive formation of keratinized tissue. In addition, VAD is manifested especially in rapidly developing and differentiating tissues, such as oral mucosa, digestive and respiratory tract, urinary tract, skin and endocrine outputs. Dehydration occurs, keratinization and atrophy. Smell and taste are impaired, and malabsorption can occur. Due to the damage of the ciliated epithelium, serious infections such as pneumonia may occur. Thus especially in the children VAD is the leading cause of death. Other symptoms of deficiency are also observed in non-epithelial cells and tissues, such as in embryonic tissue, bone marrow, bones and teeth. The deficiency is the cause of reproductive disorders, such as atrophy of the testes and ovaries, congenital malformations and fetal absorption. It is also causing defective formation of the organic matrix, growth retardation and bone deformities (HESEKER et al. 2009, p. 486f.).


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The contribution of orange-fleshed sweet potatoes towards nutrition security in rural areas in Mwanza, Tanzania
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Nutrition security, sweet potato, Tanzania, Vitamin A
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Verena Schmidt (Author), 2011, The contribution of orange-fleshed sweet potatoes towards nutrition security in rural areas in Mwanza, Tanzania, Munich, GRIN Verlag,


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