Review: Meta-analysis of the association between production diversity, diets, and nutrition in smallholder farm households

Undernutrition and low dietary diversity remain big problems in many developing countries. A large proportionof the people affected are smallholder farmers. Hence, it is often assumed that further diversifying small-farmproduction would be a good strategy to improve nutrition, but the evidence is mixed. We systematically reviewstudies that have analyzed associations between production diversity, dietary diversity, and nutrition insmallholder households and provide a meta-analysis of estimated effects. We identified 45 original studies re-porting results from 26 countries and using various indicators of diets and nutrition. While in the majority ofthese studies positive results are highlighted, less than 20% of the studies report consistently positive and sig-nificant associations between production diversity and dietary diversity and/or nutrition. Around 60% reportpositive associations only for certain subsamples or indicators, the rest found no significant associations at all.The average marginal effect of production diversity on dietary diversity is positive but small. The mean effect of0.062 implies that farms would have to produce 16 additional crop or livestock species to increase dietarydiversity by one food group. The mean effect is somewhat larger in Sub-Saharan Africa than in other regions, buteven in Africa farms would have to produce around 9 additional species to increase dietary diversity by one foodgroup. While results may look differently under very specific conditions, there is little evidence to support theassumption that increasing farm production diversity is a highly effective strategy to improve smallholder dietsand nutrition in most or all situations.