Assessing the Impact of Livestock Husbandry on Anemia in Women and Children: A Systematic Review

Anemia is a major public health concern among women and children in low‐ and middle‐income countries (LMICs) and can result from both micronutrient deficiencies (nutritional anemia) and infection (anemia of inflammation). Livestock husbandry may positively impact anemia through provision of animal‐source foods (ASF) and income, but may also contribute to the development of anemia through infectious disease. Sustainable livestock production and management interventions may thus provide an avenue to address preventable causes of anemia. The objective of this review is to assess the impact of livestock husbandry on anemia in women and children and to identify the mechanisms underlying this relation including diet, micronutrient status, and infection. Using a priori exclusion criteria and a systematic search of databases of indexed literature, we identified fourteen observational and two experimental studies that empirically measured the association of livestock husbandry with anemia or its potential determinants. Out of the thirteen studies that reported measures of anemia or iron status, seven observed a lower prevalence of anemia with exposure to or increased production of livestock. Six studies examined pastoral populations and four of these found a higher prevalence of anemia in pastoral populations as compared to settled or farming populations. Some authors hypothesized that this higher prevalence of anemia may be due to a greater burden of infection among pastoralists. This livestock‐pathogen interface is supported by findings of increased hookworm and S. stercoralis in children living in households owning livestock, and of a higher incidence of human illness with increasing animal illness or death. No studies assessed sub‐clinical infection associated with environmental enteric dysfunction. Although livestock rearing may increase exposure to infection, it may also increase access to nutrient‐rich ASFs. Of the five studies that assessed ASF consumption, two found a positive association between animal ownership and consumption of those animals, and three found positive associations of ASF consumption with anemia. Of the two identified experimental studies that randomly assigned households to receive a poultry production intervention, only one observed a significant reduction in anemia among infants. This result was dependent on the type of educational platform that households received in concert with the poultry production intervention. Although livestock ownership and rearing is associated with a lower prevalence of anemia among women and children in some contexts, particularly among those with greater ASF consumption, a high risk of infection from livestock exposure may detract from these potential benefits in other contexts. The evidence base to assess this relation and its mechanisms would benefit from additional experimental studies that distinguish nutritional anemia from anemia of inflammation and further consider how livestock management and increased animal production may influence determinants of anemia in the long‐term.