Evidence in multiple micronutrient nutrition: from history to science to effective programs

Multiple micronutrient interventions are efficacious, but research on adequacy, plausibility, and implementation needs attention

Evidence for the efficacy of multiple micronutrient (MMN) supplementation has been established by state-of-the-art randomized controlled trials (RCT). These efficacy trials have also provided strong evidence of the widespread occurrence of deficiencies. Trials intended to demonstrate a public health benefit must show that the magnitude of benefit is adequate for policy considerations. In the MMN efficacy studies the magnitude of impact was generally inadequate. The extent to which this was due to various factors that affect individuals' potential to respond to MMN supplementation has not been examined, and trials have not been designed to provide insights into why impact is below expectation. For instance, when birth weight was the outcome of concern, impact was not related to presumed need, judged by baseline birth-weight values. Also, contrary to expectations, the impacts were greater among the heavier mothers. Our inability to examine issues of adequacy, plausibility, and implementation with efficacy trial approaches as they are currently conducted, calls into question the present standards for designing and interpreting community RCT in nutrition. Improving the capacity of efficacy studies to yield more meaningful data requires a number of modifications to current practices, such as including measures of the intermediary behavioral and biological steps between intervention and biological outcomes to assess the adequacy and plausibility of the findings. The progression from RCT to program interventions must also extend research to program delivery and uptake to ascertain the full program impact pathway. This in turn requires novel organizations of relationships between research and program development and implementation.