Optimal cognitive and emotional development and physiological function in children and adolescents requires access to food of adequate quantity and quality at all stages in life. Recurrent food insecurity as experienced in Ethiopia 1 may result in malnutrition with resulting developmental impairments such as poor learning capacity in children 2 3 4 . Food insecurity adversely affects intellectual development 2 3 5 6 7 , school attendance 8 , growth 7 , health 9 academic performance and social skills 2 5 7 of children and adolescents.

There are different mechanisms through which food insecurity could negatively affect educational attainment. A frequently mentioned pathway is through high rates of school absenteeism, with children living in food insecure households being pulled form school to engage in productive activities. It has been hypothesized that this might be particularly true for girls. Another of the mechanisms is through decreased intake of nutrients during periods of reduced food supply. Although various studies have shown that adult household members buffer children from food insecurity 10 11 12 13 ; alterations in the eating behaviour of food insecure adolescents in a way that affects their nutritional status 8 14 have been reported. Children who experience food insecurity might also suffer from a significant amount of psychological and emotional stress at home around the concerns of the caregivers to provide adequate food. This may affect the emotional well-being of the adolescent to an extent that interferes with cognitive 15 16 17 and behavioral performance 18 . Food-insufficient teenagers were reported to have behavioral problems that are incompatible with their school attendance 5 .

Several longitudinal 2 3 19 and cross-sectional 5 6 18 studies in high income countries have shown a relationship between household food insecurity as reported by the head of the household and adverse educational outcomes in younger children. This relationship, however, has not been explored in low income countries. To our knowledge there are no studies on the effect of adolescent's personal experience of food insecurity on school absenteeism and educational attainment from both high or from low income countries where food insecurity is prevalent. Assessing the link between adolescent food insecurity and school absenteeism and educational attainment is critical to design and integrate multi-sectoral strategies aiming to achieve the Millennium Development Goal 2, "Universal Access to Primary Education", in Ethiopia. We hypothesized that the proportion of school absentees would be higher in the food insecure adolescents compared to their food secure peers and that the food insecure adolescents would have a lower educational attainment as well.

Out of the 2100 adolescents intended, 2084 completed the questionnaires. For further analysis of absenteeism we excluded 75 adolescents who were not enrolled in the school. Bivariate analyses showed that a significantly higher proportion (33.0%) of food insecure adolescents was identified as absentees compared with food secure youth (17.8%), P < 0.001. School absenteeism was positively associated with household food insecurity (P < 0.001) and number of hours per week that the adolescents had to work for the household (P < 0.001). Similarly, 51.0% adolescents from households with severe food insecurity reported absenteeism compared to 36.3% of adolescents who were not part of severely food insecure households (P < 0.001). A larger proportion (24.9%) of adolescents who reported an illness during one month prior to the survey also reported absenteeism compared to those who did not report an illness (11.1%, P < 0.001). The mean educational level attained (Table 1), expressed as the highest grade completed at the second survey was 6.2 ± 2.5 for non-absentees and 5.9 ± 2.3, for absentees (P = 0.047).

Figure 1 shows the frequency of school absenteeism by food security status of adolescents. The frequency of school absenteeism was significantly higher among food insecure adolescents (P < 0.001). While the majority (67.8%) of food secure adolescents was never absent, the frequency of school absenteeism among food insecure youth ranged from several days per week (29.2%) to several days per semester (15.7%). After stratification by gender, a significantly (P < 0.001) higher proportion (34.5%) of food insecure girls were absent compared to boys (15.0%). This gender difference in absenteeism was not significant(P > 0.05) in the food secure adolescents (Figure 2).

The mean (± SD) highest grade completed after 1 year was 6.0(± 2.7) for food secure adolescents and 5.5(± 2.7) for food insecure adolescents (P = 0.003). Similarly, adolescents from households with severe food insecurity had lower mean grades mean (± SD) completed 5.5(± 2.7) compared to those from household that did not have severe food insecurity (6.2 ± 2.7, P < 0.001). The proportion adolescents who completed primary education (grade 8) was higher (31.5%) for food secure adolescents compared to food insecure adolescents (24.1%, P < 0.01).

Multivariable logistic regression model (Table 2) showed that food insecure adolescents were nearly twice as likely to be absent from school [OR 1.77 (1.34-2.33)] compared to their food secure peers after adjusting for age, gender, place of residence and gender of household head. Similarly, severe household food insecurity [OR 1.6 (1.27-2.06)], illness reported during the last month [OR 2.26 (1.68-3.06)] and the number of days the adolescents had to work for at least one hour per week [OR 1.16 (1.07-1.26)] were positively associated with school absenteeism. Adolescents who aspired to higher grades were less likely to be absent from school compared to their peers who aspired to a lower grade [OR 0.92 (0.88-0.96)].

In bivariate linear regression models, adolescent food insecurity (P < 0.001), severe household food insecurity (P < 0.001), residence in rural area (P < 0.001) and female gender (P = 0.043) were negatively associated with educational attainment, while age of the adolescent (P < 0.001), highest grade aspired to be attained by the adolescent(P < 0.001), residence in urban area (P < 0.001), residence in semi urban area (P < 0.001) and household income (P < 0.001) were positively associated with educational attainment.

After adjusting for all other variables in the multivariable linear regression model (Table 3), food insecure adolescents attained a lower grade after 1 year of follow-up compared to food secure adolescents (β = -0.44, P < 0.001). Female gender (β = -0.18, P = 0.039), being a member of a severely food insecure household (β = -0.41, P < 0.001) and residing in a rural area (β = -2.70, P < 0.001) or semi-urban area (β = -0.92, P < 0.001) were negatively associated with educational attainment. However, age (β = 0.66, P < 0.001) and the highest grade aspired to be completed by the adolescent (β = 0.17, P < 0.001) were positively associated with educational attainment. The effect of household income and gender of the household head disappeared in the adjusted model.

Food insecurity is a common problem among adolescents and households in Southwest Ethiopia 13 27 . The present study shows that food insecure adolescents and adolescents who were members of severely food insecure households were more likely to be absent from school and have a lower educational attainment in terms of the highest grade completed after 1 year of follow-up in Southwest Ethiopia. Food insecure adolescents had on average a lower grade completed (5.5) compared to food secure adolescents (6.0). The proportion of food insecure adolescents who completed primary education (24.1%) was also significantly lower than that of food secure adolescents (31.5%), although both proportions were lower than the national completion rate of primary schools in 2005-2006 28 . Food insecure adolescents are likely to have a lower educational attainment due to several reasons including high absenteeism, illness, poor academic performance, academic delays, poor social functioning and behavioral problems 2 3 6 . According to Food and Agricultural Organization of the United Nations, hungry children start school later, drop out sooner and are also more likely to be absent and learn less while they do attend 29 .

The effect of food insecurity on physical health and wellbeing is one of the ways through which food insecurity can erode educational attainment. As adolescence is a critical period of human growth and development, it can be affected by nutritional constraints resulting from food insecurity. There is an increasing recognition that ill health and malnutrition among school aged children have a major impact of on their cognitive development, learning and educational achievement. Improved health and nutrition are positively associated with enrolment at younger age, reduced absenteeism, less grade repetition and higher performance on test scores 30 31 due better cognitive development 32 . Cross-sectional studies from high income countries show that when food supplies are constrained at the household level, both adults and children use coping strategies such as reduction of meal size and meal frequency and eating lower quality foods 14 , which in turn might induce malnutrition 8 . Similarly, cross-sectional 5 and longitudinal studies from high income countries 3 7 and a cross sectional study from a low income country 33 also showed that malnutrition is associated with poor cognitive development and decreased school performance in children. Malnourished children are less able to concentrate in school 3 18 29 , which could lead to lower educational attainment.

In this study, adolescents who reported an illness during the last month were twice as likely to be absent from school. A report from the study area showed that food insecure adolescents had a higher frequency of illness than food secures ones 9 13 . Food insecurity not only jeopardizes the right to health but also has serious implications on education and schooling of adolescents. Secure access to food may enhance school attendance and overall health and well-being through decreasing use of negative coping strategies 30 31 .

Food insecurity can also act as a psychological or emotional stress factor 15 34 35 , affecting adolescent behavior and aspiration for further education. Our findings show that adolescents who aspire to complete higher grades were 18% less likely to be absent from school. The effect of food insecurity on children's well-being is related to its effect on the physical and socio-emotional aspects 3 4 that are linked to developmental consequences through nutritional and non-nutritional mechanisms 3 . While the nutritional effects might explain the negative consequences of inadequate nutrient intake on physical health and cognitive development, non-nutritional aspects of food insecurity relate to psychological effects including worry, anxiety or sadness about the family's food supply, feelings of having no choice in the foods eaten, shame/fear of being labeled as poor which are beyond the nutritional effects of food insecurity on adolescents 18 . Cook and Frank reported that food insecurity is a common risk to the growth, health, cognitive, and behavioural potential of children in constrained situations 35 . Children living in constrained environments were reported to have significantly higher cortisol levels due to stress 15 . Prolonged elevated cortisol level in humans have been associated with depression, cognitive deficits, and atrophy of brain structures involved in learning and memory 16 17 which may also lead to lower educational attainment. As a result of stress, anxiety and disrupted household dynamics 18 , food-insufficient teenagers are more likely to have behavioral problems which makes them incompatible with school norms 5 negatively impacting on their educational attainment. Any of these mechanisms, alone or combined, could explain how food security affects the educational attainment of adolescents in the study area. Interventions focusing on improving the food insecurity situation such as conditional cash and/or food transfer programmes 36 need to consider these consequences on adolescents in identifying target groups.

After stratifying for gender, the bivariate analysis showed that in food insecure situations a higher proportion of girls are more likely to be absent from school compared to boys. This might be related to the social norms in the community that give low value female to education 37 that are potentially exacerbated when resources are constrained. A significantly larger proportion of girls was from food insecure households, food insecure themselves and reported an illness during the past one month compared to boys. This may be due to the selective buffering of boys from food insecurity by adult household members that is common in the study area 13 . The higher rates of food insecurity in girls could result in their school absenteeism through mechanisms discussed above. When entering gender as a variable in the multivariable model for school absenteeism however, no significant association was observed (results not shown), which indicates that the effect of gender is mediated by the other variables in the model.

School absenteeism in this study was also determined by a high frequency of work at the household level that the adolescent was engaged in. Adolescents who had to work longer hours per week were 1.4 times more likely to be absent from school. Children become absentees or dropout of school to help household labor as one of the coping strategies of food insecurity 38 .

Our results imply that secure access of adolescents to food supply needs to be given attention to achieve the targets of the Millennium Development Goal. The findings provide arguments to incorporate food security in interventions that aim to address school attendance. Interventions including food stamp programs 2 and school breakfast programs 39 were reported to have beneficial effects for children on academic learning through improving dietary intake and/or reduction of stress. School supplementation program were also shown to have beneficial effects in reducing scholastic difficulties of adolescents 40 . In Ethiopia although such programs are being implemented by relief actors as part of an emergency response 41 there is no school feeding programme in non-emergency scenarios. There is a need to consider such interventions in potentially food constrained areas to prevent attrition of food insecure adolescents from school.

We acknowledge a number of limitations in our study. Although the adolescent and household food security scales were adapted from household food security scales after thorough discussion with the interview team who are residents of the study area, we might not rule out the possibility of some misclassification. The scales used assessed acute food insecurity as they covered only the last three months prior to the interview. The total survey period involved two seasons (rainy/peak hunger season) and spring season 42 which is better off in terms of food security and this matches a follow up period of one year. The proportion of food insecure households was 39.4% which was similar to estimations for urban areas of the region 38 . When interpreting the results of the study, it is important to note that our findings regarding food insecurity relate mainly to the study season and might not reflect the total year, but this is not a problem for the absenteeism variables. In addition, household food insecurity might be associated with adolescent food insecurity, which could introduce co-linearity in the models. The correlation coefficient between household food insecurity and adolescent food security was 0.2 and variance inflation factors in both logistic and linear regression models were generally low (the highest observed was 1.08), which indicates no considerable co-linearity in our analysis.

As the study involved adolescents who are at the different stages of academic status, we used the highest grade completed as a measure of educational attainment that can serve across all age groups. However, there are other measures of educational attainment that were not captured. The fact that we did not have data from the school records regarding the academic performances is also a limitation of our analysis.

We report that food insecurity negatively impacts on school attendance and educational attainment of adolescents in the Southwest Ethiopia. The findings suggest that food security interventions should consider ways of enhancing school attendance and look into mechanisms for improving the diet of school children directly through school based programs.

The authors declare that they have no competing interests.

The authors' responsibilities were as follows: DL, CH, TB & AG: Designed and supervised the study and ensured quality of the data and made a substantial contribution to the local implementation of the study and PK, CL, CH & DL assisted in the analysis and interpretation of the data. All authors critically reviewed the manuscript. TB, the corresponding author did the analysis & drafted the manuscript and had the responsibility to submit the manuscript for publication.