Dietary diversity is defined as the sum of the food groups consumed over a period of 24 h. It is widely recognized and accepted as a determinant of nutritional outcome1. It is therefore a key element of high-quality diets and the recommendation to consume a variety of foods appears in many nutritional guidelines2. Dietary diversity is essential to the consumption of adequate nutrients because there is no single food other than breast milk for the first six months of life that contains all of the nutrients required to maintain good health and nutritional status2. Consuming a wide variety of foods among and within food groups is a recommended strategy to help ensure an adequate intake of nutrients3. A diverse diet is important for meeting the requirements for essential nutrients, especially for those who are at risk of nutrient deficiencies4.
Malnutrition refers to an abnormal physiological condition caused by inadequate or excessive consumption of macronutrients and micronutrients5. Malnutrition could be reduced by increasing the diversity of foods available for consumption6 because non-diverse diets can have negative consequences on individuals’ health, well-being and development, as this type of diet is unlikely to meet the micronutrient requirements7. A lack of dietary diversity is a particularly severe problem among economically disadvantaged populations in the developing world8.
Ukehe is a rural community in Nsukka with school-aged children (SAC) who may be at risk of malnutrition as a result of the inadequate intake of diverse foods, intra-familial food distribution, culture, food insecurity and poverty, which is likely to result in poor intellectual development. The implication is that there will be decreased academic performance, growth retardation and an elevated prevalence of underweight. This is because insufficient daily consumption of different foods has been found to affect an individual’s health and nutritional status, which may hinder a child’s ability to learn9. Conducted in a rural area with marked economic deprivation, this study was designed to assess the associations of dietary diversity with academic performance and anthropometric indices in primary school children (6-12 years) in Ukehe, Nigeria.
MATERIALS AND METHODS
Study area and design: This study was carried out in Ukehe, a rural community in Igbo-Etiti local government area of Enugu State where the inhabitants are mainly farmers, traders and civil servants. Ukehe is located at 60’4 North and 42’7 East. A cross-sectional survey design was adopted for this study.
Study population and sample size determination: The study population for this research was composed of all (1044) primary school children aged 6-12 years old in Ukehe in the Igbo-Etiti local government area, Nsukka. Fifty percent (522) of the study population was used as the sample size for this study.
Sampling technique: A multistage sampling technique was used to select the respondents for this study.
||Stage 1: A list of all the primary schools in Ukehe was obtained from the Enugu State Universal Basic Education Board.
||Stage 2: The school registers in each school were used to identify school children who were within the age range of 6-12 years (n = 1044). This constituted the study population
||Stage 3: A proportionate sampling technique was used to determine fifty percent of the school children (6-12 years) in each school
||Stage 4: Random sampling by balloting without replacement was used to select the school children who participated in the study. Those who picked ‘yes’ were recruited for the study. This gave every school child an equal chance of being represented.
Data collection methods: Data were collected using the following methods:
Preliminary visit: The Igbo-Etiti Local Government Education Board was visited with an introductory letter from the Head Department of Home Science, Nutrition and Dietetics to obtain the population of government primary school children in Ukehe, Igbo-Etiti local government area, Nsukka. A preliminary visit was also made to obtain permission to carry out the study from the various school authorities
Ethics clearance and informed consent : An ethics clearance certificate with the reference number MH/MSD/REC18/013 was obtained from the Health Research Ethics Committee of the Ministry of Health, Enugu state. Consent from the respondents to be part of the study was obtained through their care-givers (parents and guardians). A meeting was held with the caregivers of the respondents to explain in detail what the study entailed. At the end of the meeting, consent forms were issued to the caregivers to sign indicating their approval to enable their children participate in the study. Respondents whose caregivers gave consent were recruited for the study, whereas those who declined were replaced
Questionnaire: A structured and validated questionnaire was used to obtain information on the personal data of the respondents, socioeconomic status of the parents, dietary diversity, anthropometric measurements and academic performance of the children. The questionnaire was interviewer-administered to the children and their caregivers.
Anthropometric measurements: Anthropometric measurements of weight and height were obtained from the respondents.
Weight measurement: The weight of the subjects was measured using a Hanson bathroom scale (120 kg capacity). The scale was adjusted to zero before each measurement. The children were weighed with minimum clothing and without shoes. The reading was taken to the nearest 0.1 kg.
Height measurements: The height of the children was measured with a height meter calibrated in centimeters (cm). A good standing posture was maintained before measurement. The height of the child was measured without shoes on, with heels pulled together, head held erect and hands hanging at the sides in a natural manner. The measurement was taken to the nearest 0.1 cm.
Body mass index (BMI): The body mass index (BMI) was calculated from the weight and height measurements as follows:
Using the WHO10 reference standard, the respondent’s date of birth was used to classify them into their respective height-for-age (HAZ), BMI for-age (BAZ) and weight-for-height (WHZ) z-scores. Children with HAZ, BAZ and WHZ scores ≤−2.00 were considered to have moderate stunting, underweight and wasting, respectively, while those with scores ≤−3.00 were severely stunted, underweight and wasted, respectively.
Dietary diversity: Dietary diversity was assessed based on 24 h recall of the children’s consumption of 12 food groups within the past 24 h using the FAO5 guideline. Foods were categorized into 12 groups based on the FAO recommendations as follows: (i) Cereals, (ii) Vegetables, (iii) Fruits, (iv) Meat, (v) Eggs, (vi) Fish and other seafood, (vii) Legumes, nuts and seeds, (viii) Milk and milk products, (ix) Oil and fats, (x) Sweets, (xi) Spices, condiments and beverages; and (xii) Tubers and roots. Commonly consumed foods in the area were incorporated into each food group. The response categories were “Yes” if at least two food items in a group were consumed and this was scored as one point. However, half of a point was awarded for fewer than two food items. In cases in which a food item was not consumed in a group, zero (0) point was given, representing “No”. Dietary diversity was obtained by summing the number of food and food items consumed in each group separately. The total score was calculated and ranged from 0-12. The dietary diversity score was used to classify the children into low (≤3), medium (4-5) and high >6 categories5.
Academic performance assessment: The academic performance of the children was assessed by recording the grades scored in four subjects (English, Mathematics, Igbo and General Paper) offered during the first and second term examinations for the academic session 2017/2018. The average of the grades in the four subjects in each term was obtained. Then, the overall average score of the two terms was determined for each child as a measure of their academic performance. Academic performance was categorized as high (≥75%), average (50-74%) and low (< 50%)11.
Statistical analysis: Data collected were coded into the computer software and analyzed using SPSS (version 21.0). The results were presented as means, standard deviations, frequencies and percentages. Chi-square tests were used to analyze the relationships among variables. The associations between dependent and independent variables were established using multiple logistic regression. Significance was accepted at p<0.05.
Table 1 shows the mean dietary diversity score of the different food groups. Among the food groups, eggs (2.000±0.000), milk and milk products (2.003±0.179), sweets (1.943±0.249), fruits (1.906±0.541) and legumes, nuts and seeds (1.942±0.791) were the least commonly consumed food groups by the respondents, as indicated by their high mean values, while cereals (1.467±0.712), vegetables (1.301±0.619), oil and fats (1.048±0.283), roots and tubers (1.393±0.645) and fish and seafood (1.412±0.685) were most commonly consumed categories by the respondents.
Table 2 presents the cross-tabulation of the dietary diversity score with the anthropometric indices and academic performance. Most of the respondents who were normal in terms of their height-for-age (94.1%), BMI-for-age (93.5%) and weight-for-height (96.6%) were in the medium category for the dietary diversity score. Only 1.1% of the stunted respondents were in the low category for the dietary diversity score. Some of the respondents with medium dietary diversity score had an average score on their academic performance (31.8%). There were positive associations between the dietary diversity score and height-for-age, BMI-for-age, weight-for-height and academic performance.
Table 3 presents the socioeconomic and anthropometric variables associated with the dietary diversity score. Children who had a high dietary diversity score were 1.244 times more likely to have good academic performance, 1.761 times more likely to have mothers who were moderate income earners, 0.950 times more likely to be 6-9 years old, 1.488 times more likely to have a normal weight-for-height, 0.806 times more likely to have a normal height-for-age and 1.464 times more likely to have a normal BMI-for-age.
Majority of the respondents fell within the medium dietary diversity group, which was contrary to the findings of Ukegbu and Ogu4 who reported that the majority (73.5%) of the children in some rural areas of Imo State, Nigeria, were in the low level of dietary diversity. Mahbubur et al.6 reported high level of dietary diversity in the majority (52%) of school-aged children in Bangladesh whereas Katungwe et al.12 reported that 48.7% of rural school children in Ntchisi district of Malawi had minimum diversity.
Mean dietary diversity indifferent food groups
SD: Standard deviation
Cross-tabulation of the dietary diversity score (DDS) with anthropometric indices and academic performance
High DDS: ≥6 food groups, Medium DDS: 4 and 5 food groups, Low DDS: ≤3 food groups, Freq.: Frequency
Association of dietary diversity score (DDS) with socioeconomic and anthropometric variables
The minimum (≥4) requirement for dietary diversity, which was met by the majority, was higher than that reported in Northwest Ethiopia13. The medium level of dietary diversity score observed in the majority of the respondents could be responsible for the low prevalence of underweight, wasting and stunting among the school children.
Although most of the caregivers had low monthly incomes, their children had medium and high levels of dietary diversity score. The reason for this may be that in addition to engaging in business and civil service, some of the caregivers have inherited farmlands where they cultivate food crops that provide an additional source of food for the family. This finding is inconsistent with the report of Kumera et al.13 who observed that those with low monthly income were less likely to have children with medium and high levels of dietary diversity.
It was observed that the majority of the respondents had an average academic performance, which was higher than the average academic performance (40%) reported in Sadder town, Karachi14. A child that is well fed or who has good nutrition will increase in weight, focus better and thereby perform better academically. Dietary diversity was positively associated with academic performance, showing that high dietary diversity translates to high academic performance.
Dietary diversity has been shown to correlate with nutrient intake and various anthropometric measurements in children15. There were positive associations between dietary diversity and anthropometric indices in the respondents, similar to the report of Wemakor and Laari16 in Ghana and to the findings of Steyn et al.17 in South Africa, who found significant correlations between the dietary diversity score and the height-for-age and weight-for-age Z-scores, indicating strong relationships between dietary diversity and indicators of child growth. Several studies have reported that low dietary diversity is associated with an increased likelihood of child stunting18and a double burden of malnutrition19.
Stunting which measures the cumulative deficient growth associated with long-term factors including insufficient dietary intake, frequent infections, poor feeding practices over a sustained period and a low socioeconomic status of households10 was not of public health significance (<10% prevalence) in Ukehe, Enugu state according to the WHO criteria20. The prevalences of stunting and underweight in this study were lower than the findings of Ene-Obong and Ekweagwu21 among school-aged children in Ebonyi state Nigeria, who reported stunting and underweight prevalences of 42.5 and 23.3%, respectively. Low weight-for-age (underweight) encompass chronic and/or acute malnutrition20. Nwamarah et al.22 reported 19.5 and 8.5% prevalences of stunting and underweight among school-aged children in Okpuje, Nsukka L.G.A, Enugu state. These low prevalences could be a result of low dietary diversity that existed in few of the children, indicating that they had access to different types of food because Ukehe is a rural area with good agricultural practices and has varieties of nutritious foods and dishes. Steyn et al.17showed significant correlations between the dietary diversity score and the height-for-age and weight-for-age Z-scores contrary to the findings of this study.
The term wasting is widely used to describe a recent and severe process that has led to significant weight loss usually as a consequence of acute starvation and/or severe disease20. There was a low prevalence of wasting in this study compared to earlier report21 on school children in Ebonyi state (6.1%) and among primary school children in the Obukpa rural community, Nsukka (6.3%)23. Akor et al.24 reported a 2.4% prevalence in Jos, Plateau state, Nigeria among school-aged children.
Overweight had a low prevalence in the present study compared to those reported by Obianuju et al.25 (8.5%) among school children in Enugu, Nigeria. This variation could be a result of the nutrition transition that exists more in urban than in rural areas where this study was performed. Overweight and obese children are likely to stay obese into adulthood and are more likely to develop non-communicable diseases like diabetes and cardiovascular diseases at a younger age26. Therefore, an increase in BMI should be prevented early in life. Seasonality (rainy season) and the area of study (rural area) could have contributed to the high consumption of vegetables (which were in season) by the majority of the respondents. The 24 h dietary diversity assessment revealed that cereals, vegetables, oil and fats, roots and tubers and fish were the foods most commonly consumed by the respondents. Similar results have been reported by Ukegbu and Ogu4 who studied dietary diversity score among children in some rural areas of Imo State, Nigeria and reported that cereals (0.78±0.29), vegetables (0.78±0.30), oils and fats (0.67±0.28), fish and other seafood (90.61±0.28) and roots and tubers (0.48±0.36) were commonly consumed by the children. More consumption of roots and tubers, which constitute the major staple food in Ukehe, was consistent with the findings of Nwamarah et al.,22, who reported that cassava- based foods were mostly consumed by the respondents in the Okpuje community. This was probably because the majority of the parents engaged in farming and/or business or civil service. Farmers cultivate and have access to crops with which they feed their families. In addition, rural business owners have direct contact with the market where they access foods in season, which they know how to buy at a less expensive rate.
Among the primary school children (6-12 years), stunting, wasting and underweight existed. Underweight was the most prevalent. Most of the respondents were in the category of medium dietary diversity score. Children with normal anthropometric indices had high levels of dietary diversity. The dietary diversity score was positively associated with anthropometric indices and academic performance.
Given the importance of the dietary diversity score in determining diet quality, this study shows that dietary diversity is associated with academic performance and anthropometric indices. This study helps researchers understand the diet quality of rural school children and how it affects their growth, development and intellectual capability. Thus, the results will highlight dietary diversity as an indicator of nutritional adequacy, which may be linked to high academic performance in rural areas.