Intrahousehold Dimensions of Micronutrient Deficiencies: A Review of the Evidence

Although micronutrient deficiency is a global problem, it is not a universal one; the burden is not evenly shared within countries or households. Empirical evidence from 69 studies compiled for this review indicates that there are important non-linearities in relationships among food intakes, sharing and caring behaviour, and micronutrient status that lead to a diversity of outcomes not always predictable by age or gender. Mothers and girls display a higher prevalence of some deficiencies than men or boys, but the situation is confounded or reversed in other contexts. No single age cohort, gender or location is invariably worse off than every other, all of the time. The manifestation of deficiencies is determined by synergies among nutrients, diseases and biological functions, on the one hand, and interacting social, economic and environmental processes, on the other. The unmasking of age and gender diversity in risks and outcomes is important for better establishing the global prevalence of micronutrient problems and for improving the focus of public action. The tools used in assessing deficiencies need to be re-examined in light of multiple interactions among micronutrients, on the one hand, and among health and behavioural confounders, on the other. Understanding local dietary practices, health care preferences, activity patterns and tradeoffs in resource access is as crucial as specifying physiological benchmarks. Clinical rigour needs to be combined with rigourous contextual insight. The conventional narrow focus on one deficiency, for one priority group at a time needs to be questioned. Progress in tackling single micronutrient problems for single target groups may not mean that everyone is, or remains, better off. Sustainable gains for whole populations are likely to require combinations of actions at various levels to influence the incentive and behaviour structures operating down to the intrahousehold level.