In the past few decades, many studies have entered the “micronutrient area”, examining the benefits of micronutrients in health, especially in the context of improving maternal and child health. In particular, micronutrient deficiencies early in life lead to growth faltering, which results in stunting and its associated adverse outcomes such as impaired cognitive development and child death (1).
Initially, the first studies examined the health benefit of single nutrients such as iron, zinc, and vitamin A. Some of them have translated into supports for large-scale programs in resource-poor environments. Prevention of child anemia with iron supplementation, reduction of child morbidity following zinc supplementation and decrease of child mortality with high-dose vitamin A supplementation figure among the best-known examples.
Later on, mounting evidences suggested that providing several micronutrients in combination would be more beneficial and cost-effective than single nutrient interventions. Indeed, micronutrient deficiencies hardly ever occur isolated. Moreover, improved micronutrient absorption and other synergic effect can be achieved with a multiple micronutrient intervention (2, 3).
Although generally showing beneficial outcomes for child health, physical growth, survival and anemia, the results from multiple micronutrient interventions studies still show great variations, mainly due to a disparity in the nature of the interventions (compositions, dosage, duration, mode of delivery, frequency, etc.) as summarized in a review article published in 2011 in the Journal of Nutrition (4). Furthermore, as mentioned by the authors, other sources of results variability can be found in feeding practices and, more importantly, in the background prevalence of different deficiencies and/or infections such as HIV or Malaria.
A study conducted with more than 400 Vietnamese infants, and published about one year later in the same scientific journal, further examined the differential effect of traditional complementary food (consisting of gruels made of rice flour, with addition of oil seeds, vegetables, sugar, salt and glutamate) versus locally produced micronutrient-fortified complementary foods on growth faltering and stunting (5). The results showed that regular supplementation with micronutrient-fortified complementary foods succeeded in partially stopping growth faltering. The improved growth observed in the intervention groups could also be partially explained by an overall better immune status.
Interestingly, the study also showed differential long-term effects according to the type of micronutrient-fortified complementary food: a ready-to-use, micronutrient-fortified instant flour showed better sustained beneficial effects on long-term length and ponderal growth than a micronutrient-fortified food powder to be added to traditionally prepared rice gruels.
The results of multiple micronutrient interventions studies support combinatorial micronutrition as a key approach to fighting impaired child growth. They also suggest that beneficial outcomes might be better sustained over time with complete fortified foods rather than pure food complements. However, they also pointed out that multiple micronutrient interventions might only be beneficial if they take into account the whole picture, that is the general environment of a target population. This includes local food availability, common deficiencies, as well as general prevalence of diseases and infections. Indeed, child malnutrition in African countries with high HIV prevalence, for instance, cannot be addressed the same way as in Asia.
This implies that multiple micronutrient interventions need to be designed with a clever combinatorial approach in order to be tailored for a target population. Compositions, rational proportions and types of the provided fortified complementary foods are crucial for beneficial outcomes.
1. Walker, S. P., et al. (2007). Child development: risk factors for adverse outcomes in developing countries. Lancet 369, 145-57 2. Ramakrishnan, U., Nguyen, P. and Martorell, R. (2009). Effects of micronutrients on growth of children under 5 y of age: meta-analyses of single and multiple nutrient interventions. Am J Clin Nutr 89, 191-203 3. Allen, L. H., Peerson, J. M. and Olney, D. K. (2009). Provision of multiple rather than two or fewer micronutrients more effectively improves growth and other outcomes in micronutrient-deficient children and adults. J Nutr 139, 1022-30 4. Ramakrishnan, U., Goldenberg, T. and Allen, L. H. (2011). Do multiple micronutrient interventions improve child health, growth, and development? J Nutr 141, 2066-75 5. Pham, V. P., et al. (2012). A six-month intervention with two different types of micronutrient-fortified complementary foods had distinct short- and long-term effects on linear and ponderal growth of Vietnamese infants. J Nutr 142, 1735-40