Non-linear education gradient across the nutrition transition: mothers' overweight and the population education transition

Abstract

Objective: Previous studies found that developed and developing countries present opposite education-overweight gradients but have not considered the dynamics at different levels of national development. An inverted U-shaped curve is hypothesized to best describe the education-overweight association. It is also hypothesized that as the nutrition transition unfolds within nations the shape of education-overweight curve changes.

Design: Multilevel logistic regression was used to estimate the moderating effect of the nutrition transition at the population level on the education-overweight gradient. At the individual level, a non-linear estimate of the education association was used to assess the optimal functional form of the association across the nutrition transition.

Setting: Twenty-two administrations of the Demographic and Health Survey, collected at different time points across the nutrition transition in nine Latin American/Caribbean countries.

Subjects: Mothers of reproductive age (15-49 years) in each administration (n 143 258).

Results: In the pooled sample, a non-linear education gradient on mothers' overweight was found; each additional year of schooling increases the probability of being overweight up to the end of primary schooling, after which each additional year of schooling decreases the probability of overweight. Also, as access to diets high in animal fats and sweeteners increases over time, the curve's critical point moves to lower education levels, the detrimental positive effect of education diminishes, and both occur as the overall risk of overweight increases with greater access to harmful diets.

Conclusions: Both hypotheses were supported. As the nutrition transition progresses, the education-overweight curve shifts steadily to a negative linear association with a higher average risk of overweight; and education, at increasingly lower levels, acts as a 'social vaccine' against increasing risk of overweight. These empirical patterns fit the general 'population education transition' curve hypothesis about how education's influences on health risks are contextualized across population transitions.

Keywords: Education; Latin America; Mother’s overweight; Nutrition transition; Obesity risk; Population education–health curve.

Fig. 1

Nutrition transition (NT) status of the sampled country-time units in comparison with Africa* and the USA (from FAO^{( 52 )})†. *FAO provides the aggregated information on each continent. This NT status of Africa contains all countries in Northern, Southern, Western and Eastern African regions. †The NT statuses of Africa and the USA indicate the average value during 1991–2009. Note that FAO statistics provide the information related to NT until 2009. Therefore, the NT index of Colombia 2010 was assumed to be the same as that of Colombia 2009. ‡NT status indicates the percentage of animal fats and sugar/sweeteners in the total food supply in each country. For example, 30 in BR-1996 (the second column from the right) means that a Brazilian consumed 30 % of his or her energy intake as animal fats and sugar/sweeteners in 1996 (LAC, Latin American and Caribbean countries; BO, Bolivia; BR, Brazil; CO, Colombia; DO, Dominican Republic; GT, Guatemala; HT, Haiti; HN, Honduras; NI, Nicaragua; PE, Peru)

Fig. 2

Curvilinear gradient of the education–mother’s overweight association across all nutrition transition statuses (model 2, Table 2) among mothers of reproductive age (15–49 years; n 143 258) across twenty-two administrations of the Demographic and Health Survey in nine Latin American/Caribbean countries

Fig. 3

Curvilinear gradient of the education–mother’s overweight association by nutrition transition (NT) status* (a, low NT status; b, medium NT status; c, high NT status; model 3, Table 3) among mothers of reproductive age (15–49 years; n 143 258) across twenty-two administrations of the Demographic and Health Survey in nine Latin American/Caribbean countries. *The division into different NT statuses is based on the average percentage of NT status in the sampled countries. Low NT status indicates the group with 2 sd below the average NT, medium NT status represents the average group of NT, and high NT status denotes the group with 2 sd above the average NT