Drivers of Pigeon Pea Consumption Among School-Aged Children in Central Tanzania

Background: Protein energy malnutrition (PEM) and iron deficiencies (ID) are of major public health concern in Tanzania including among school-aged children. PEM and ID in early childhood have serious, long-term consequences because they impede motor, sensory, social and emotional development, growth retardation, poor cognitive development, learning disability of children, lowered resistance to infectious diseases, and reduced physical work capacity. The objective of this study was to elucidate the drivers of pigeon pea consumption among school-aged children in Dodoma district, Central Tanzania. Understanding these drivers would be useful in promoting pigeon pea consumption among school-aged children as one of the strategies to increase dietary protein and iron intake.

Methods: This study was a cross-sectional study in which data were collected using a questionnaire based on a combination of the Theory of Planned Behavior and Health Belief Model. The data were collected from caregivers (n = 138) in four villages in Kongwa district, Dodoma region, Central Tanzania. We used correlations and multiple regressions to assess associations between constructs and identify predictive constructs. Mann–Whitney U tests were used for score comparisons with a significant p-value set at <0.10.

Results: Health value was significantly correlated with health behavior identity (r_s = 0.63, p < 0.001) and also significantly predicted health behavior identity (r_s = 0.49, p = 0.001). The constructs cues to action and control belief were significantly associated with intention (β = −0.41, p = 0.059 and β = 0.06, p = 0.019 respectively). Finally, we observed that intention was a significant predictor of behavior (β = 1.38, p = 0.001). We also observed a significant negative interaction between perceived barriers and intention to consume pigeon pea (β = −0.04, p = 0.006), indicating that perceived barriers limit intention to consume pigeon pea.

Conclusion and Implication: Our findings indicate that when the caregiver places increased importance on preventing her school-aged child from being iron or protein deficient or indeed anemic (health value), it results in a positive evaluation of the effectiveness of giving pigeon pea to address these nutrient deficiencies. Programs and efforts aimed at promoting pigeon pea consumption should focus on educating caregivers on iron and protein deficiency and the role that pigeon pea could play in addressing these. However, perceived barriers such as pest infestation during storage need to be addressed to increase pigeon pea consumption. The involvement of post-harvest management specialists is therefore crucial. Along with this, increasing productivity and crop management is also crucial to ensure year-round affordable supply of pigeon pea.

Introduction

Appropriate nutrition of school-aged children (SAC) (5–12 years) remains a priority since their health, physical growth, and intellectual development crucially depend on adequate provision of nutrients (WHO, 2000; Buttriss, 2002; Jomaa et al., 2011). Their school performance is dependent on optimal nutrition status (WHO, 2000) especially during a period of increased nutrient needs (Buttriss, 2002). It has been observed that inadequate nutrient consumption is strongly associated with protein energy malnutrition (PEM) and micronutrient deficiencies (Ochola and Masibo, 2014). In central Tanzania, SAC have previously been observed to have high prevalence of anemia partly due to poor food consumption, which limits their ability to thrive and benefit from education (Leonard et al., 2015). Current data indicate that SAC in developing countries mainly consume plant-based diets, which are predominantly from cereals, roots, and tubers (Kassaye et al., 2001; Murphy et al., 2003; Tatala et al., 2005; Ahmed et al., 2006; Gewa et al., 2014), thus predisposing them to nutrient deficiencies.

To address nutrient deficiencies, different strategies such as supplementation, fortification, and other food-based strategies may be utilized (Tontisirin et al., 2002). Experience has shown that food-based strategies such as improved food production and dietary diversification with nutrient-dense legumes, for example, are the most sustainable to increase the macro- and micronutrient intake in a population due to their associated multiple social, economic, and health benefits (Nair et al., 2015). This is because food-based approaches promote wellbeing and health of individuals through supporting incomes and livelihoods while providing the right to healthy food through ecologically sound and sustainable agriculture systems (Amoroso, 2014).

Pigeon pea is a grain legume that is well adapted to low rainfall patterns and thrives in low-fertility soils. It is therefore a crop that can reduce the hunger and nutrient gap in semi-arid regions, serving as a good source of protein and other micronutrients such as iron. It has a protein content of 19–21.7% and an iron content of about 2.5–4.7 mg/100 g dry matter (Amarteifio et al., 2002). The legume protein is a useful alternative (Seetha Anitha et al., 2019) to animal protein, which is not sufficient, often unaffordable and therefore hardly consumed (Schonfeldt and Gibson Hall, 2012). A recent study indicates that incorporation of legumes such as pigeon pea into diets also provides access to all nine essential amino acids, as well as Vitamin B, ascorbic acid, carotenoids, iron, and magnesium (Seetha Anitha et al., 2019). Despite this potential to meet nutrient needs, pigeon pea has been widely grown in Tanzania for export to India. In 2018, however, there was a drastic fall in pigeon pea prices, after Tanzania's' biggest market, India, banned pigeon pea exports directly affecting ~300,000 Tanzanian farmers engaged in pigeon pea farming (Malawi Investment and Trade Centre, 2018). The study described herein was embedded within a wider program that aimed to, in part, address this situation from a nutrition and health perspective as a basis for sustained production. In the semi-arid Kongwa district of Central Tanzania, we focused on promoting pigeon pea consumption via a farm (production)-to-fork (consumption) approach. Increased consumption, besides addressing nutrition directly, offers avenues for farmers to diversify markets and reduce overdependence on export markets.

The combined Theory of Planned Behavior (TPB) and Health Belief Model (HBM) employed herein have previously been used in explaining influential variables in food-related behaviors (Sun et al., 2006). Via the model, we elucidate herein the drivers of pigeon pea consumption among Tanzanian SAC.

Methods

Ethical Approval and Consent

This study did not seek approval from an ethical review board because it did not involve blood collection, any invasive procedure or anthropometry. Prior to implementation of the study, approvals from district administrative officials as well as traditional authorities were obtained. All respondents had the study explained to them in the local language, Kiswahili, and were assured of confidentiality and offered opportunity to ask questions. Respondents were also informed that they were free to decline participation prior to or at any point during the questionnaire administration. Study participants then indicated their approval by giving written consent. Where respondents could not write, approval to participate was indicated via thumb print.

Study Site

Kongwa district is one of the action districts of the Africa Research in Sustainable Intensification for the Next Generation (Africa RISING) program. The program aims to create opportunities for smallholder farm households to move out of hunger and poverty through sustainably intensified farming systems that improve food, nutrition, and income security, particularly for women and children (Hoeschle, 2021). Kongwa district is located in the eastern corner of Dodoma region and covers a land area of 4,041 km² (NBS, 2013). It borders Kiteto district to the north, Kilosa district in the east, Chamwino district in the west, and Mpwapwa district in the south. The elevation of Kongwa district ranges from 900 to 1,000 m above sea level (Figure 1).

FIGURE 1

Figure 1. Map of Kongwa district in which the study was conducted.

The district is characterized by semi-arid conditions, with rainfalls of 450–700 mm/year, but with great variability and often distributed within a very short period. The main economic activities are crop agriculture and livestock keeping. The crops that are grown include maize, pigeon pea, sorghum, and millets, while the livestock kept include cattle, goats, sheep, and pigs (NBS, 2013). The villages selected were Moleti, Laikala, Mlali, and Chitego based on their high pigeon pea production relative to other villages in the district.

Sampling and Study Participants

A sample of 138 caregivers of reproductive age (20–49 years) were randomly selected for the study. As a general rule for the TPB, a sample size of 80 is considered to be minimum and 180 is considered maximum for acceptable statistical analyses (Francis et al., 2004). Caregivers were from households with SAC (5–12 years). Households were selected using the random walk sampling method, and all caregivers from the selected households were listed. From this, one caregiver was randomly selected to represent each household for the questionnaire administration. Of the listed caregivers, the inclusion criteria were prior knowledge and consumption of pigeon pea, and willingness to participate in the study.

Development of Dietary Intake and Food Behavior Assessment Questionnaires

A focus group discussion was conducted to investigate commonly consumed protein- and iron-rich foods as well as their frequency of consumption. Pigeon pea-based recipes were also documented to enable calculation of potential protein and iron contents. Once this was established, a food frequency questionnaire where respondents were asked how many servings of pigeon pea-based foods they intend to consume in the next month was developed and administered (Appendix 1 in Supplementary Material). Along with this, the frequency of consumption of protein-rich foods in the past 7 days preceding the survey was investigated (Appendix 2 in Supplementary Material). We used a shorter period of recall for protein-based foods because these may not be frequently consumed.

Both questionnaires were validated with women who were in the villages that would eventually not take part in the actual study but had similar consumption habits.

Nutrient content of raw pulses, legumes, and groundnut commonly consumed in Kongwa were obtained from the Tanzanian food composition table (TFCT) (Lukmanji et al., 2008). Nutrient content of recipes was also obtained from the TFCT, and where the recipe was not available in totality, it was calculated from nutrient contents of the various foods that make up the recipe (Appendix 3 in Supplementary Material). Iron bioavailability of plant source foods was approximated at 5% as per previous studies by Macharia-Mutie et al. (2011).

Age-appropriate protein and iron requirements were obtained from the Food and Agriculture Organization website (FAO/WHO, 1998; FAO, 2021) and compared with the pigeon pea-based recipes for nutrient adequacy. Proportions of nutrient requirements met were calculated by dividing the amount of protein or iron provided by the meal by the daily requirements.

In terms of behavior assessment, a questionnaire based on the TPB and HBM was developed by following the procedures recommended by Sun et al. (2006) (Sun et al., 2006). The first part of the questionnaire included the socio-demographic and socio-economic status variables of the respondent. The second part consisted of 66 items, identified from literature. The items were characterized into 12 constructs based on the combined model of TPB and HBM as was undertaken in several earlier studies (Sun et al., 2006; Fanou-Fogny et al., 2011; Macharia-Mutie et al., 2011; Abizari et al., 2013; Talsma et al., 2013). The following is a description of constructs considered:

1. Knowledge assessed the caregivers understanding of the relationship between pigeon pea consumption and health, and specifically its relationship to iron deficiency or anemia and protein deficiency.

2. Perceived susceptibility assessed caregiver's feeling about her school-aged child being exposed to iron deficiency or anemia and protein deficiency.

3. Perceived severity assessed caregiver's feeling that her school-aged child being exposed to iron deficiency or anemia and protein deficiency is serious.

4. Health value assessed the importance caregiver places on the outcome of her school-aged child being iron deficient, anemic or protein deficient.

5. Health behavior identity assessed caregiver's evaluation of the effectiveness of pigeon pea consumption in reducing iron deficiency or anemia and protein deficiency.

6. Perceived barriers assessed the caregiver's evaluation of various complications that hinder her in giving pigeon pea to her school-aged child.

7. Attitude toward behavior assessed caregiver's evaluation of giving pigeon pea to a school-aged child.

8. Cues to action assessed the surrounding situation that cause a caregiver to change her health behavior in giving pigeon pea to her school-aged child.

9. Control belief assessed a caregiver's perceived ability to make a decision on giving pigeon pea to her school-aged child.

10. Subjective norms reveal a caregiver's perceived social influencers to give, or not to give, pigeon pea to their school-aged child (who is important for the behavior and is the opinion of that person important?).

11. Behavioral intention is a sign of how much effort a caregiver is planning to make, in order to give pigeon pea to school-aged child.

12. Behavior assessed the giving of pigeon pea to school-going children by caregivers.

Respondents were asked to indicate their level of agreement or disagreement with statements on a Likert scale. Pre-testing was done in sites with characteristics similar to those of the four study villages. All questionnaires were administered face-to-face by well-trained research enumerators who were familiar with cultural settings in the study area.

Scale Measurements and Analyses

Knowledge, perceived susceptibility, perceived severity, health value, health behavior identity, perceived barriers, cues to action, and control belief constructs were rated using a five-point Likert scale that ranged from strongly disagree, disagree, neutral, agree, and strongly agree. The reason that odd-numbered scales were chosen was so that a central neutral response and an equal number of positive and negative responses above and below the neutral middle response were provided (Emerson, 2017). The score for each construct was computed as the sum of individual item scores. The scores for the constructs “Attitudes toward behavior” and “Subjective norms” were sums of products of paired items; attitudes × evaluation of attitudes, and normative beliefs × motivation to comply, respectively. To show negative, neutral, or positive influences, item scores of attitudes and normative beliefs ranged from −2 to 2 and the scores of the evaluation of attitudes and motivation to comply ranged from +1 to +5. This resulted in a paired-item score range of −10 to 10. For intention and behavior, the rating scale ranged from not consumed, four or less times per month, and eight or more times per month. The scores on intention and behavior constructs were based on the number of times caregivers intended to feed or had fed their school-going child with pigeon pea in the refereed month, respectively. Intention was considered high if it was higher than the median intention score of the group, and low if it was equal to or lower than the median scores as it was in previous studies (Sun et al., 2006; Fanou-Fogny et al., 2011; Macharia-Mutie et al., 2011; Abizari et al., 2013; Talsma et al., 2013).

Statistical Analyses

Descriptive statistics were performed to describe the socio-demographic characteristics of the caregivers and their children. Multiple sentence constructs were tested for reliability of the questionnaire and internal consistency using Cronbach's α and sentence-total correlation. The items within a construct were regarded as consistent when Cronbach's α was ~0.75 or higher and the corrected sentence-total correlation of all sentences in a construct higher than 0.30 (Field, 2005). Mann–Whitney U-tests were used to examine differences in various construct items between high and low intenders. This test was used to compare whether there is a difference in the dependent variable for two independent groups (Karadimitriou, 2018). Spearman's correlation was used to test the bivariate association within the combined model of TPB and HBM. Spearman rank correlation test was selected since, in this case, ranked data were being compared (Schober et al., 2018).

Three multiple linear regression models were used to examine the contribution of constructs to health behavior identity, intention, and behavior. The first model was designed to identify constructs classified within background and perception that were associated with health behavior identity (Model 1). To identify constructs associated with intention, the second model combined internal factors (Perceived barrier, Health behavior identity, and Attitudes toward behavior) and external factors (Subjective norms, Control beliefs, and Cues to action) as predictor variables (Model 2). Finally, to identify constructs associated with pigeon pea consumption among SAC, we included constructs that were significantly associated with intention (Health behavior identity, Attitudes toward behavior, Subjective norms, Cues to action, and External control beliefs) as well as intention. The construct perceived barriers were included as a predictor because of the importance of considering the role barriers may play in influencing pigeon pea consumption. An interaction term between perceived barriers and intention was also included in this final model to investigate how perceived barriers modulated the association between intention and behavior. All models were corrected for age of the child, education, and interviewer effect.

Overall, statistical tests were two-tailed, and p-values < 0.10 were considered statistically significant. We used this p-value cutoff due to the finite sample size of our study and because this study was prone to random errors (Thiese et al., 2016). All analyses were performed using IBM SPSS Statistics for Windows (Version 20.0. IBM Corp, 2011, Armonk, NY).

Results

Background Characteristics of the Study Participants in Kongwa

A total of 138 caregivers with a similar number of SAC participated in the study. Table 1 shows the summaries for each of the background characteristics considered in this study. Half of the sampled children were male (50.7%) with 68% of the children in the age group 5 to 8 years. The biggest proportion (91.8%) of children lived with their mothers. Majority of the respondents did not have any formal education (55.8%) while 44.2% had some form of formal education. We observed that 84.8% of the respondent households earned their income through crop farming and livestock keeping. The most dominant ethnic groups were the Kaguru (65.2%).

TABLE 1

Table 1. Socio-demographic characteristicts of schoolchidren and their caregivers in Kongwa.

Consumption of Pigeon Pea and Other Iron- and Protein-Rich Foods and Their Contribution to Nutrient Adequacy

Pigeon pea-based foods were consumed in different forms: as a relish and accompaniment to stiff porridge (ugali) or rice, mixed with rice in a dish known as “mesto,” or cooked with maize grains in a dish known as “kande ya mbaazi.” The relish was consumed four to five times a week by 37.7% of the respondents compared to 23.2%, 15.2%, and 9.4% who reported to have consumed the same meal once, two, to three times a week or greater than six times per week, respectively (Figure 2). Mseto and kande ya mbaazi were consumed by the majority, respectively, by 62.3% and 65.2% of the respondents once a week.

FIGURE 2

Figure 2. Consumption of pigeon pea based foods in the seven days preceding the survey.

Other common plant-based foods consumed were bean stew, groundnuts, and green vegetables consumed by 76, 43.5, and 74.6%, respectively, once per week (Figure 3). There was frequent consumption of animal source foods that are also rich in protein and iron. In detail, 62% of the population consumed meat, 44.7% dairy foods, and 67.3% fish and sardines more than once a week. In comparison, organ meat and eggs were consumed less frequently, reported as being consumed more than once in the last 7 days by 15.2 and 26.7% of the population, respectively (Figure 3).

FIGURE 3

Figure 3. Frequency of consuming protein and iron rich foods in the 7 days preceding the survey.

The protein content of raw pigeon pea was comparable to that of other legumes such as mung bean, common bean, cow pea, and groundnut (Table 2), except for soybean, which was superior by about 15 g. However, pigeon pea has an amino acid profile that compares closely with that of soybean, with the exception of methionine (0.87 vs. 1.55 g/100 g) and cysteine (0.67 vs. 1.44 g/100 g) content for pigeon pea and soybean, respectively. On the other hand, histidine is an essential amino acid found in abundance in split pigeon pea (3.16 mg/100 g) compared with white soybean (2.55 mg/100 g).

TABLE 2

Table 2. Protein and iron content of animal source and plant foods consumed in Kongwa based on the Tanzania Food Composition Table (Lukmanji et al., 2008).

Recipes for the pigeon pea-based dishes were recorded. In general, pigeon pea relish consisted of pigeon pea fried with a small quantity of tomatoes and oil as condiments. This relish was often consumed with rice. For kande ya mbaazi, it was prepared similarly to the pigeon pea relish only that 50% of the pigeon pea in the recipe was replaced with maize. It was estimated that the rice-pigeon pea dish (mesto) consisted of 20% pigeon pea. Assuming a consumption of 336 g per meal based on a study in SAC in Kenya (Talsma et al., 2013), the potential protein and iron intakes from the three-pigeon pea-based meals were calculated as follows and is also elaborated in Appendix 3 in Supplementary Material:

1. Pigeon pea relish nutrient content is recorded in the Tanzania food composition table (Lukmanji et al., 2008). The iron content in the pigeon pea relish is 2.8 mg/100 g. Considering a 5% bioavailability, iron content in the pigeon pea relish in this calculation is considered as 0.14 mg. Based on a consumption of 336 g per meal, pigeon pea relish was ~40% of the meal, that is, 134.4 g. Rice in this meal would supply an estimated Fe and protein content of 0.03 mg [(201.6/100) ^* 0.02] and 5.8 g [(201.6/100) ^* 2.9], respectively. A pigeon pea relish and rice meal would thus supply 0.22 mg of iron and 24.4 g of protein.

2. A similar amount of pigeon pea and maize mix would consist of 50% pigeon pea and 50% maize. Based on a 336-g meal, 118 g of pigeon pea in the mix would supply 0.17 mg [(118/100) ^* 0.14] of iron and 16.3 g [(118/100) ^* 13.8] of protein. Iron content in cracked maize that is used in this recipe is 1.2 mg. Considering 5% bioavailability, iron content in this calculation was considered as 0.06 mg. Maize in this recipe would supply 0.07 mg [(118/100) ^* 0.06] of iron and 3.2 g [(118/100) ^* 2.7] of protein. In total, the meal would thus potentially supply 0.24 mg (0.17 mg + 0.07 mg) of iron and 19.5 g (16.3 g + 3.2 g) of protein.

3. For mseto, in 336 g, there would be 67.2 g of pigeon pea and 268.8 g of rice. Rice had a recorded iron content of 0.3 mg, with a bioavailable iron of 0.02 mg (0.03 mg ^* 0.05). Fe and protein content from pigeon pea were recorded as 0.04 mg iron [(67.2/100) ^* 0.14] and 4.1 g protein [(67.2/100) ^* 6.1], respectively. The estimated Fe and protein content from the rice was 0.05 mg iron [(268.8/100) ^* 0.02] and 7.8 g protein [(268.8/100) ^* 2.9], respectively. In total, this recipe would provide an estimated 0.08 mg Fe and 11.9 g protein.

Based on the above, pigeon pea relish eaten with a rice accompaniment would potentially meet 96% of the iron requirements for children 5–6 years, 69% for those 7–10 years, and 40% for males and females 11–14 years. The pigeon pea maize mix or kande would meet all the iron requirements for 5–6-year-olds, 75% for 7-to-10-year-olds, 44% for those 11 years and older. In terms of protein requirements, a 336-g pigeon pea relish and rice meal would meet 100% of the protein requirements for 5–7-year-olds, 90% for 7–10-year-olds, 70 and 68% for 10– 12-year-old boys and girls, respectively. Mseto met the least proportion of iron and protein requirements for SAC. A 336-g meal would meet 35% of iron requirements for 5–6-year-olds, 25% for 7–10-year-olds, and 15% for those over 11 years. When protein requirements were considered, mseto would meet 57% of protein requirements for 5–7-year-olds, 44% for 7–10-year-olds, and 35% and 33% for 10–12-year-old boys and girls, respectively. Iron and protein requirements are presented in Table 3.

TABLE 3

Table 3. Protein and iron requirements for school-aged children (5–11 years).

Drivers of Pigeon Pea Consumption

When comparisons between intention and behavior were made at the consumption level of at least eight or more times a month, a significant difference was observed (57.2 vs. 58.7% respectively; p = 0.089). There was no significant difference between intention and behavior for consumption levels of four or less times a month (37.7 vs. 34.1%, respectively; p = 0.615) or where there was neither no intention to consume nor consumption (5.1 vs. 7.2%, respectively; p = 0.467). These comparisons are represented via bar graphs in Figure 4.

FIGURE 4

Figure 4. Intention to consume pigeon pea in the coming month and behavior (pigeon pea consumption) of the last month (n = 138).

Internal Drivers Influencing Pigeon Pea Consumption Among School-Aged Children

The internal drivers were identified by assessing the caregiver's knowledge about the relationship between food or nutrients and health as well as their subjective perception of the school children being malnourished and iron deficient or anemic (perceived severity). Nearly all caregivers recognized food as playing a vital role in the health of their children (95.7%) but did not think that food can prevent iron deficiency (48.6%) or know that pigeon pea contains high levels of protein (48.6%) and iron (30.4%). Additionally, majority did not know that protein is important for the growth and health of their children (67.4 and 47.8%, respectively). In terms of the role of nutrients, 37.0% of respondents knew that protein could prevent their children from becoming underweight and 27.5% understood that iron is important in preventing iron deficiency or anemia. Less than half of the caregivers had knowledge of the benefits of pigeon pea as a protein-based food that could prevent underweight in their child or iron deficiency and anemia.

More than half (63.8%) of caregivers perceived anemia as affecting growth, intelligence (65.2%), and school performance (65.9%). A slightly higher proportion recognized anemia as being associated with the child's level of activity (77.5%) as well as mortality (73.9%). In terms of health value, majority of respondents agreed that the following aspects of their school-aged child were important to them: weight (94.9%), growth (96.4%), intelligence (97.8%), school performance (97.1%), strength (94.2%), and survival (97.1%). However only about half of the respondents agreed that iron was important for cognition (50.0%) and activity (58.7%; Table 4).

TABLE 4

Table 4. Internal and external factors influencing pigeon pea consumption.

In terms of health behavior identity, almost all (93.5%) caregivers perceived giving pigeon pea as one of the best things that they could do. They also thought of pigeon pea as one of the best foods they can give to improve intelligence (71.7%), health (87.7%), and survival of their school child (85.5%). High intenders had a significantly higher appreciation of the role of foods that contain iron in improving cognition (74.6 vs. 60.9%; p = 0.022) and pigeon pea in particular being important for cognition (74.1 vs. 61.7%; p = 0.031) (Table 5; Supplementary Table 1). The findings indicate a gap in knowledge such that caregivers could not connect the benefits of pigeon to the nutrients present in them.

TABLE 5

Table 5. Comparison between high and low intenders of pigeon pea consumption.

Majority of the respondents perceived pigeon pea seasonality (65.9%) and weevil attacks (77. 5%) as barriers to consumption (Table 4). When analyses were stratified according to high- and low-intention groups, there was no significant difference in these aspects (Supplementary Table 1). In terms of other aspects considered as possible barriers, we also observed significant differences between high and low intenders when preparation time was considered (61.4 vs. 74.3%; p = 0.003) and amount of fuel required for preparation (62.7 vs. 73.5%; p = 0.081; Table 5). A significantly higher number of low intenders considered preparation time as a barrier to pigeon pea consumption.

To influence consumption, it is crucial to understand the disposition of the caregiver toward giving pigeon pea to the schoolchild (attitude toward behavior). Majority of caregivers perceived pigeon pea as tasty (97.8), and with good aroma (78.3%) and color (84.1%), as indicated in Table 4. Furthermore, a significantly higher proportion of high intenders compared to low intenders (71.0 vs. 66.9%; p = 0.021) considered pigeon pea as tasty (Table 5). Other factors appreciated by majority of the respondents were easy digestibility (81.2%) and easy preparation (81.9%).

External Drivers Influencing Pigeon Pea Consumption Among School-Aged Children

Majority of respondents agreed that gatherings such as religious ceremonies, harvest time, women meetings, and the advice from the health workers (76.1% each) influenced their choice to feed pigeon pea to their SAC. Majority of the respondents valued doctors' (93.5%) advice to feed pigeon pea to their SAC. High intention groups had a significantly higher value for advice from nurses and doctors (74.9 vs. 60.3%; p = 0.020 and 72.4 vs. 64.6%; p = 0.010, respectively; Table 5). Other groups' opinion perceived as important include village leaders (87.7%), religious leaders (85.5%), teachers (81. 2%), mothers (87.7%), and husbands (75.4%) with no significant difference in opinion between high and low intenders (Table 4; Supplementary Table 1).

Finally, we elucidated how all the individual constructs influence pigeon pea consumption with an aim to identify specific drivers of pigeon pea consumption among our respondents. As a first step, the reliability of our constructs and then correlations between these constructs were determined.

Associations of Constructs With Pigeon Pea Consumption

Cronbach's α coefficients demonstrated high reliability of the constructs with values ranging from 0.70 to 0.88 (Table 6). Three constructs (control belief, intention, and behavior) consisted of only one item each, and therefore, the reliability analyses were not carried out for these constructs. The median scores ranged from 4 (control beliefs) to 69 (attitudes toward behavior). Median scores of perceived severity, health value, health behavior identity, perceived barriers, attitude, and subjective norms constructs were high compared to the range values. This showed that caregivers tended to agree with the statements in those constructs. On the other hand, there were low median values of knowledge, perceived susceptibility, cues to action, control beliefs, intention, and behavior construct compared to their range scores, indicating that most caregivers tended to disagree with the statements. Control belief, behavioral intention, and behavior constructs consisted of only one item each, and therefore, their reliability analyses were not conducted (Table 6).

TABLE 6

Table 6. Internal consistency and median scores of the constructs.

In terms of correlations between constructs related to internal factors, knowledge (r_s = 0.29, p = 0.001), perceived severity (r_s = 0.32, p = 0.001), and health value (r_s = 0.63, p = 0.001) were significantly correlated with health behavior identity. Within beliefs and attitudes constructs, health behavior identity was significantly correlated with attitude toward behavior (r_s = 0.51, p = 0.001). In terms of external factors associated with intention, only cues to action (r_s = 0.19, p = 0.03) was significantly but weakly correlated with intention. Finally, we observed a significant correlation between intention and consumption of pigeon pea among SAC (r_s = 0.26, p = 0.002). Detailed correlation and p-values are represented in Figure 5 and Supplementary Table 2.

FIGURE 5

Figure 5. A combined model of the Theory of Planned Behavior and Health Belief Model with spearman correlation coefficients between related constructs P < 0.10 (2-tailed).

Via regression analyses, a combination of factors that predict pigeon pea consumption among SAC was identified.

Intention as a Predictor of Behavior

The relative contribution of various independent variables to the outcome variables for models 1–4 is shown in Table 7. Model 1 accounted for 29% of the variance in health behavior identity and the construct health value significantly predicted health behavior identity (β = 0.45, p = 0.000). Therefore, as the the importance the caregiver placed on the consequences of her school-aged child being iron deficient, anemic, or protein deficient increased, so did the evaluation of the role of pigeon pea consumption in addressing this.

TABLE 7

Table 7. Constructs associated with health behavior identity, intention to feed pigeon pea to school-aged children, and feeding pigeon pea to school-aged children.

In Model 2, we included the internal and external factors as predictors of intention. The constructs control belief (β = –0.41, p = 0.059) and cues to action (β = 0.06, p = 0.019) significantly predicted intention and accounted for 8% of the variance in intention. Interestingly, the more agency the caregiver had in terms of giving pigeon pea to her SAC (Control belief), there was less effort from her end to ensure this consumption. However, when surrounding situations such as Ramadan or doctors' advice were considered (Cues to action; β = 0.06, p = 0.019), they positively influenced the caregivers' efforts to ensure consumption of pigeon pea.

Model 3 accounted for 22% of the variance in behavior. Intention significantly predicted behavior (β = 1.32, p = 0.001), indicating that as the effort a caregiver was planning to make to ensure pigeon pea increased, the likelihood that her child consumed pigeon pea also increased. Similarly, as the caregiver's evaluation of the effectiveness of pigeon pea consumption in addressing iron deficiency or anemia and protein deficiency in her SAC increased (Health behavior identity), consumption of pigeon pea was more likely (β = 0.09, p = 0.044). Finally, as complications such preparation time, fuel required, and scarcity due to the season were increasingly experienced by the caregiver (perceived barriers), the less likely she was to ensure pigeon pea consumption by her SAC (β = –0.17, p = 0.002). In fact, perceived barriers negatively affected the effort the caregiver was willing to make to ensure her SAC consumed pigeon pea (Perceived barriers ^* Intention to consume pigeon pea, β = –0.04, p = 0.006).

The relative contribution of the predictor variables to the outcome variables for Models 1–4 is shown in Table 7.

Discussion

The last 5 years have been turbulent for the pigeon pea industry worldwide. India is the highest consumer and was also the biggest importer of pigeon pea. Approximately 50% of these imports are from Myanmar, while the other 50% were from Africa—with Tanzania contributing the majority of the imports (ICRISAT, 2019). Farmers in Tanzania ramped up production of pigeon pea to meet the demands of this export market. However, domestic production in India almost doubled in 2016–2017 from the previous years. Along with this, there was a change in trade regulations by the Indian government to support domestic farmers leading to a drastic dip in exports of pulses to India. This greatly affected Tanzania pigeon pea farmers who were exporting as much as 90,000 tons valued at about US$ 80 million, and now export about 30,000 tons. To guarantee a local market for pigeon peas, Tanzania could take advantage of the crop's appreciable protein and iron contents to promote domestic consumption through awareness-creation and the inclusion of pigeon pea in national food assistance programs, such as school feeding. This will not only provide a market avenue for farmers but also offer nutrient-dense food to the local population. This is a crucial opportunity as domestic consumption of pigeon pea remains low (Zahra Saidi Majili et al., 2020).

We show in this study that the protein content of raw pigeon pea is comparable to that of other legumes and nuts such as mung bean, common bean, cow pea, and groundnut. Also, its amino acid profile is comparable to that of soybean. In combination with this, we observe that consumption of animal source foods (including dairy) was relatively lower than that of animal source foods (ASF). Indeed, within developing countries, dietary protein sources are mainly limited to cereals and, to a much lesser extent, to animal sources (Schonfeldt and Gibson Hall, 2012). In fact, data show that in these countries, only 3% of dietary energy is derived from animal products, 11% from roots and tubers, and 6% from pulses, while the remainder is made up mainly of cereals (FAO, 2008). This indicates that though our respondents reported a high frequency of animal source food consumption, it is likely that the quantities consumed are minimal and therefore have a low contribution to nutrient intake. Pigeon pea could thus be an alternative to fill the protein nutrient gap.

Our respondents reported consuming three types of pigeon pea recipes. This likely limits the frequency of consumption of pigeon peas due to the monotony. Worldwide, pigeon peas can be used in a variety of recipes, thus increasing the organoleptic properties (Saxena and Rao, 2002; Opoku et al., 2003; Torres et al., 2007; Okpala, 2011; Ayenan et al., 2017; Olanipekun et al., 2018) and thereby increasing the frequency of their consumption. A study by Figueira et al. (Chinyoka, 2016) has however reported the lack of knowledge surrounding legumes' preparation and the time involved in this preparation as limiting factors for the consumption of legumes. For this reason, community knowledge on preparation of various pigeon pea recipes should be improved so as to widen culinary attribute choices and increase the frequency of consumption.

This study was nested within a project that ultimately aimed to increase pigeon pea consumption among various groups that included SAC. Nutritionally deficient children are more likely not to perform well in school and score poorly in cognitive tests due to slow memory recall and attention problems than well-nourished children (Taras, 2005; Best et al., 2010; Chinyoka, 2016). However, this can be remedied as it has been shown that improving nutritional status subsequently improves cognition and academic performance among school children (Eilander et al., 2010; Best et al., 2011). Cross-sectional, longitudinal, and intervention studies show that iron deficiency (with or without anemia) in particular has adverse effects on cognitive development and performance in children (Grantham-McGregor and Ani, 2001; Pivina et al., 2019). Anemic children have poorer cognition and school achievement than non-anemic children (Hermoso et al., 2011; Ignacio, 2014). Current worldwide data show that more than 40% SAC in developing countries are suffering from anemia and it is considered a severe public health problem. Sub-Saharan African countries shared a greater burden of this problem (United Nations Children's Fund/United Nations University/World Health Organization (WHO), 2001; Tatala et al., 2008). Unfortunately, there are no published data sources on the iron or anemia status of school-going children in Tanzania. It is plausible to assume that within the Tanzanian context, anemia among SAC would be common based on the anemia burden in Africa.

Although a myriad of factors lead to the development of anemia, iron deficiency does play an important role in its etiology (Tariku et al., 2019). Addressing iron deficiency and anemia in SAC needs greater attention due to the aforementioned consequences. SAC are a neglected group in terms of micronutrient interventions since most intervention strategies are targeted at preschool children or pregnant women. Food-based strategies may be a useful strategy to target this group. Pigeon pea in particular may contribute as a sustainable solution as combining them with other food groups will improve the quality of diet, hence reducing the chances of malnutrition. Despite this potential, the crop is not adequately consumed in Tanzania. It has been estimated that the per-capita consumption of legumes in Tanzania is 14.14 g/day/person, which is less than the 30 g/day/person recommended by the Food and Agriculture Organization of the United Nations (FAO) (Mfikwa and Kilima, 2014). In our simulation, we observe that some of the recipes consumed have the potential to meet iron requirements per day especially for the 4–10 years age group. To ensure that huge groups of school-going children are targeted, pigeon pea could be included in school feeding programs. In terms of acceptability of such an approach, a previous study in Tanzania had positive feedback on pigeon pea from rural schools where over 2,000 students were surveyed. After the intervention, 87% of students changed their perception of pigeon pea and 91% voted to keep them in their school meals (Wangari et al., 2020).

To increase consumption of crops such as pigeon pea at both household and institutional level, it is crucial to identify the drivers of its consumption. We observe that intention to consume pigeon pea was a significant predictor of consumption (r_s = 0.26, p < 0.001; Figure 5). Cues to action was directly associated with a greater intention to consume pigeon pea. Specifically, feasts such as Ramadhan and health workers' advice were mentioned as important in increasing pigeon pea consumption by over 70% of the respondents. Since the respondents value health workers' advice, nutrition education could be extended through health centers. However, such an approach runs the risk of limiting reach as it would be limited to mainly those seeking reproductive and child health services. This is because the education provided in these centers mostly focuses on maternal and infant feeding, with little given on the nutritional well-being of other groups, especially those not of reproductive ages. Such education should also therefore be incorporated widely to involve producers/farmers through farmer field schools, for example, schools and institution chefs. Respondents also identified village and religious leaders, teachers, mothers, and husbands as crucial influencers and they should be included in nutrition education campaigns. This is especially in light of the fact that we observed that when the caregiver had to make the decision on pigeon pea consumption alone, she was less likely to ensure its consumption, indicating that external influences are crucial to address. Additionally, this approach where various education avenues are used for nutrition education is useful where literacy levels may be low. The majority of our respondents had no formal education or had not completed primary education and therefore may lack knowledge on nutritious and diversified diets. Indeed, we observed this as our respondents could not make the connection between the benefits of pigeon pea consumption and their nutritive value.

We observed that perceived barriers negatively influenced the intention to consume pigeon pea. The specific perceived barriers mentioned by majority of the respondents were price especially during the rainy season and potential pest infestation during storage. A previous study conducted in the Lindi region of Tanzania also observed seasonality as affecting consumption of pigeon pea (Zahra Saidi Majili et al., 2020). In Lindi, the frequency of the consumption of pigeon peas decreases during the lean season for all kinds of pigeon pea dishes. Pigeon pea in the Lindi region was mainly consumed as greens and was only available at the end of the rainy season. Additionally, the alternative dry pigeon pea recipe required time for preparation and farmers preferred to utilize their time on farms rather than on food preparation. Within our investigated population, availability of pigeon pea was limited by seasons as most households were limited in their storage capacity. One way to address this is to introduce innovative processing technologies to increase availability year-round. As storage capacity is increased, training on post-harvest handling of pigeon pea is therefore crucial to households.

Insect pests are a major constraint to pigeon pea production in east and southern Africa region (Abass et al., 2014; Anastasia and Njoroge, 2019). Our findings of pest damage being of concern among smallholder pigeon pea farmers in central Tanzania have previously been observed in a study conducted in Central and Northern Tanzania by Abass et al. (Abass et al., 2014). In this study, 16% of the farmers considered storage pests as one of the factors causing poor crop yields and aggravating food losses. In addition, survey results suggested that the farmers' poor knowledge and skills on post-harvest management were largely responsible for the food losses. Bruchids are the most important storage pests among the various pests that cause storage loss in pigeon pea. These include three major species viz., Collosobruclus chinensis (L.), C. maculatus (F.), and C. analis (F.) (Prabhakar, 1979). The post-harvest losses due to bruchids in various pulses have been reported to vary between 30% and 40% within a period of 6 months (Akinkurolere et al., 2006; Soumia et al., 2017). Developing pigeon pea varieties that combine both grain and pod resistance may assist in enabling resistance to bruchid attack. In addition, identifying best practices and innovative technologies related to storage should be a priority to improve income and nutrition of farm households. Furthermore, increasing farmers' knowledge on proper use of improved post-harvest storage technologies would have an impact on the ability of smallholder households to reduce food losses.

Conclusions and Recommendations

In the study area, pigeon peas could be among the most important food crop for meeting iron and protein requirements. However, limited recipes due to lack of knowledge, prices during the rainy season, pest attack, preparation time, and fuel requirements are among the barriers identified. Pulses, such as pigeon pea, support a lower carbon footprint because they are nitrogen-fixing crops requiring very little, if any, nitrogen fertilizer and therefore are part of a sustainable diet (Stefanie Havemeier and Joanne, 2017). All these necessitate not only the need to develop new recipes and provide cooking demonstrations but also the need to conduct research that finds innovative ideas for the development of diversified and shelf-stable products to ensure year-round supply of convenient products. In terms of nutrition education, influential situations such as feasts, the health profession, village elders, mothers, and husbands need to be co-opted into nutrition education programs to increase consumption. Additionally, the design of nutrition education programs should emphasize on promoting healthy eating to all age groups, thus improving consumption of pigeon peas throughout the year. Linking agriculture to nutrition in this aspect also remains crucial so that avenues such as farmer field schools or agriculture extension may be engaged in relaying messages on post-harvest handling, storage, and pigeon pea preparation and consumption.

Data Availability Statement

The raw data supporting the conclusions of this article may be made available upon request by the authors, without undue reservation.

Ethics Statement

Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. The patients/participants provided their written informed consent to participate in this study.

Author Contributions

WG-W: project administration, conceptualization, methodology, interpretation of results, visualization, writing—original draft, and writing—review and editing and supervision. RM: questionnaire validation and administration, data analyses, interpretation of results, visualization, writing—original draft, and writing final draft—review and editing. MC: data analyses, interpretation of results, visualization, writing—original draft, and writing final draft-review and editing. JM: data analyses and interpretation and review and editing manuscript. NK, YM, HMs, and HMu: questionnaire development and validation, administration, and review of final draft. MB and PO: supervision and review of final draft. All authors contributed to the article and approved the submitted version.

Funding

This research publication was made possible with support from the United States Agency for International Development (USAID) through the Africa Research in Sustainable Intensification for the Next Generation (Africa RISING) program as part of the US Government's Feed the Future Initiative. The funders had no role in the design and/or implementation of the study or the preparation of the manuscript thereof.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher's Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Acknowledgments

The authors wish to thank the administrative and local authorities as well as all caregivers/respondents from Moleti, Laikala, Mlali, and Chitego villages that participated in the study. The support of Mr. Peter Ngowi in identifying potential respondents for the survey is appreciated. Additionally, we thank the interviewers for their work in the field. Furthermore, we are grateful to Tanzania Agricultural Research Institute (TARI) Hombolo for all the logistical support. The authors also acknowledge various contributions by the International Institute for Tropical Agriculture (IITA).

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fsufs.2021.726404/full#supplementary-material

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