The efficacy of health and nutrition interventions in develop- ing countries has been established for decades (for example, Gwatkin, Wilcox, and Wray 1980). Prospective studies in sev- eral settings showed that health interventions with or without supplementary foods caused children to thrive and survive better: studies in Narangwal, India (Kielmann and others 1978; Taylor, Kielmann, and Parker 1978); by the Institute for Nutrition for Central America and Panama (Delgado and others 1982); in Jamaica (Waterlow 1992); and in The Gambia (Whitehead, Rowland, and Cole 1976) are examples. 2 These studies showed the effect of interventions on growth and (usu- ally) mortality but did not generally factor out the relative con- tributions of health and.
