Effects of vitamin B9 and B12-fortified corn flour on cognitive function in teenage girls: a randomized controlled trial in Ethiopia.

PURPOSE: Adequate status in vitamins B9 and B12 supports neurological processes, and observational studies consistently associate sufficient intake with enhanced cognitive performance in adolescents. However, causal evidence on whether food fortification with these vitamins improves cognition in healthy adolescent girls remains scarce. This study evaluated the effect of consuming vitamin B9- and B12-fortified corn flour on the cognitive function of teenage girls in Arba Minch, South Ethiopia.

METHODS

We conducted a randomized, double-blind, controlled community trial from December 2023 to August 2024. A total of 472 teenage girls from schools within the Arba Minch Health and Demographic Surveillance System were randomly allocated to either the intervention (n = 235) or control group (n = 237). The intervention group received bi-weekly distributions of corn flour fortified with vitamin B9 (2 mg/kg) and B12 (0.02 mg/kg) for six months, while the control group received unfortified corn flour. Cognitive function was assessed using a multidomain test battery at baseline and endline. The intervention effects were analyzed using analysis of covariance.

RESULTS

Of the 472 participants, 417 (88.35%) completed the trial: 207 in the intervention and 210 in the control group. After six months, no significant effects of fortification with vitamins B9 and B12 were observed on any primary cognitive measures compared to the control. In secondary analysis, however, girls with stunting (height-for-age z-score < -2 standard deviation) who received the intervention showed slower performance in the language subtest of the Language and Memory Test (LMT) than girls without stunting.

CONCLUSION

A six-month intervention with vitamin B9- and B12-fortified corn flour did not improve the cognitive function of teenage girls. However, language performance among those who received fortified flour varied by their stunting status. Future randomized controlled trials with longer durations are recommended, with particular attention to adolescence as a critical developmental window.

TRIAL REGISTRATION: https://clinicaltrials.gov/ ; NCT06100146; October 3, 2023.