Dietary diversity moderates household economic inequalities in the double burden of malnutrition in Tanzania

Background Improved food availability and a growing economy in Tanzania may insufficiently decrease preexisting nutritional deficiencies and simultaneously increase overweight within the same individual, household, or population, causing a double burden of malnutrition (DBM). We investigated economic inequalities in DBM at the household level, expressed as a stunted child with an overweight/obese mother, and the moderating role of dietary diversity in these inequalities. Methods We used cross-sectional data of 2,867 children (aged 6–23 months) and their mothers (aged 15–49 years) from the 2015–2016 Tanzania Demographic and Health Survey. The participants were categorized into two groups based on their dietary diversity score: achieving and not achieving minimum dietary diversity. We assessed the interaction effect between household wealth and dietary diversity on DBM and examined the association between household wealth and DBM in subgroups based on achieving minimum dietary diversity. Logistic regression models with sample weights and restricted cubic spline functions were used for the analysis. Results The prevalence of DBM was 5.6% (SD=0.6) and significantly varied by regions (ranging from 0.6%–12.2%). Significant interaction was observed between dietary diversity and household wealth index ( p for interaction = 0.01). The prevalence of DBM monotonically increased with greater household wealth among those who did not achieve minimum dietary diversity ( p for trend = 0.002; however, but this association was attenuated in those who achieved minimum dietary diversity ( p for trend = 0.15), particularly for the richest households ( p = 0.43). Similar results were observed when modeling the household wealth index score as a continuous variable (odds ratio [95% confidence interval]: 2.05 [1.32-3.19] for non-achievers of minimum dietary diversity, 1.39 (0.76─2.54) for achievers). Conclusions Greater household wealth was associated with higher odds of DBM in Tanzania; however, achieving minimum dietary diversity may mitigate the negative impact of household economic status on DBM. What is already known on this topic? The double burden of undernutrition and obesity is increasing in low- and middle-income countries and has serious and lasting developmental and socioeconomic impact. Household economic inequalities have been linked to the double burden of malnutrition (DBM) at the household level. However, existing evidence is conflicting and limited in Tanzania. Diversified diet may mitigate the potential adverse impact of household economic inequalities on DBM; however, evidence is scarce. What this study adds? This study is one of the few attempts to explore economic inequalities in DBM at the household level in Tanzania by considering the moderating role of dietary diversity in these inequalities. The prevalence of DBM varies regionally and is unequally distributed across levels of household wealth nationwide in Tanzania. Greater household wealth is associated with higher DBM; however, achieving minimum dietary diversity mitigates the negative impact of household wealth on DBM. How this study might affect research, practice or policy? This study provide evidence that supports the hypothesis that dietary diversity might be an underrated action target for addressing DBM. Our findings encourage the implementation of double-duty approaches that simultaneously tackle different forms of malnutrition through operations such as nutrition education interventions for mothers with young children and relevant public health nutrition programs and policies in Tanzania.