Figure 1. Proportion of children that are stunted (UNICEF, WHO and World Bank, kindly reproduced from ‘Our World in Data’).

Inset details describe the landmark INCAP study and the proposed SHINE study, both of which provide long-term follow-up of a nutrition intervention. Data from the landmark INCAP study in Guatemala 50 years ago indicate that early-life improvements in nutrition can confer long-term benefits for cognition. Children receiving additional nutrition by age 2 years initially had only modest effects on neurodevelopmental scores; however, in long-term follow-up, those who had received the nutrition intervention had higher IQ scores, greater work capacity and earnings (among men) and greater schooling (among women) ⁴ . The INCAP study was conducted at a time when global stunting prevalence was much higher (1969–1977): 50% of the study population had HAZ<-3.0, while currently worldwide 22% children have HAZ <-2.0. Furthermore, the impact of the intervention on linear growth was much greater than that seen in trials of complementary feeding interventions over the past 20 years (+0.62 HAZ compared to +0.11 HAZ). Thus, although the Guatemala trial suggests that complementary feeding interventions can have substantial long-term physical and neurodevelopmental benefits, it does not reflect today’s situation in which Africa has the highest stunting prevalence, severe stunting is relatively rare but moderate stunting is 20–40%, and the average impact of interventions on HAZ is only 0.1-0.2. UNICEF, United Nations Children's Fund; WHO, World Health Organization; INCAP, Institute of Nutrition of Central America and Panama; SHINE, Sanitation Hygiene Infant Nutrition Efficacy; HAZ, height-for-age Z-score; Ppln, population; Rnd, randomisation technique; Intn, Intervention; WASH, water, sanitation and hygiene.