Background Given the well-documented risks of undernutrition, micronutrient deficiencies and adverse health outcomes associated with poor dietary quality, we examined the effect of behaviour change communication (BCC) on dietary diversity (DD) among adolescent girls in a resource-poor urban setting. Methods We conducted a quasi-experimental study with an embedded qualitative component to contextualise quantitative findings. We enrolled 700 adolescent girls aged 11–17 years (350 intervention and 350 comparison) in Bauniabadh, Mirpur, Dhaka, Bangladesh between April 2022 and November 2023. We also conducted focus group discussions (FGD) with 22 parents from intervention areas. The intervention group received two times-monthly BCC sessions for 6 consecutive months, along with zinc and iron-folic acid supplementation; the comparison group received no intervention. We assessed the primary outcome as change in DD using the Women’s DD Score. Secondary outcomes included household DD, haemoglobin level and nutrition knowledge. We estimated intervention effects using difference-in-difference (DID) analysis implemented in R (V. 4. 4. 2) and analysed qualitative data using thematic content analysis. Results The mean (SD) age of participants was 13. 5 (1. 7) years, and approximately half were enrolled in secondary education. The median (IQR) family income was US212. 9 (158. 4 to 280. 6). Knowledge on health and nutrition improved significantly at endline in the intervention group. DID analysis showed a significant increase in the haemoglobin levels in the intervention group (adjusted coefficient (aCoeff. ): 0. 60, 95% CI 0. 44 to 0. 76, p value <0. 001). We observed no significant change in DD (AOR: 0. 09, 95% CI −0. 06 to 0. 23, p value=0. 263). FGD indicated that rising food prices constrained parental purchasing power. Conclusion Community-based BCC with supplementation improved knowledge and haemoglobin level but did not improve DD among adolescent girls. Achieving sustainable nutritional gains requires integrated strategies that combine nutrition education with improved household food security, affordability and active parental engagement in similar resource-poor settings. Trial registration number NCT05311436.
Farzana et al. (Fri,) studied this question.