Yu-Ju Chen, Academia Sinica, Taiwan
While proteins are widely recognized as playing key roles in nearly all processes in living organisms, an odd debate arose about the role of protein in the diet of malnourished children in developing countries.
Stunting affects about one-quarter of children under five years of age worldwide; the World Health Organization estimates that 156 million children were stunted in 2015, nearly all of whom live in low-income countries. Stunted growth is closely linked with impaired brain and organ growth and higher risks for obesity, diabetes and other chronic diseases later in adulthood. In the 1950s and 1960s, protein-rich food mixtures were the main focus of study as a treatment for malnutrition in children in developing countries. In 1974, a paper “The Great Protein Fiasco” published in The Lancet cast doubt upon the central role of protein in childhood malnutrition. The focus in the international nutrition community shifted from proteins to micronutrient malnutrition, that is, lack of vitamins and minerals for the following four decades.
A recent study of essential amino acids and child stunting challenged the widespread belief that children in developing countries receive adequate dietary protein. The work led by Richard Semba from Johns Hopkins University was published in the April 2016 issue of the journal EBioMedicine. Semba and colleagues applied a targeted MRM-mass spectrometry-based metabolomics approach to measure serum levels of amino acids, as well as other essential compounds including glycerophospholipids, sphingolipids and other metabolites in blood samples from a community-based study of more than 300 children ages 1 to 5 years, more than 60 percent of whom had stunted growth, from six villages in rural southern Malawi. Participants’ height and weight were recorded by trained field workers. The main finding is that children with stunting had lower serum concentrations of all nine essential amino acids (tryptophan, isoleucine, leucine, valine, methionine, threonine, histidine, phenylalanine, lysine) compared with nonstunted children. In addition, stunted children had 10 to 40 percent lower concentrations of other nutritional markers, such as conditionally essential amino acids (arginine, glycine, glutamine), nonessential amino acids (asparagine, glutamate, serine) and six different sphingolipids, which are essential ingredients for development of the brain. Stunting was also associated with alterations in serum glycerophospholipid concentrations.
Essential amino acids cannot be synthesized by the body. The richest sources of essential amino acids are animal-source foods, such as milk, eggs, and meat, and also soybeans. This study suggested that children need quality protein in their diet for normal growth. These results are stimulating new recommendations and approaches to child malnutrition. Semba and his colleagues hope that this research will prompt a broader discussion on how to address child malnutrition.
“Providing high-quality protein with sufficient levels of essential amino acids in developing countries will be a major challenge and will require substantial investment in the agricultural sector,” says Semba (quoted from press release of John Hopkins University, February 23, 2016).
This study challenges a long held paradigm about dietary protein for children in developing countries. Future studies are needed to address how lack of essential amino acids affects biological pathways and contributes to the pathogenesis of child stunting. Let’s look forwards to more discoveries from the proteomic community.
Dr. Lacey LaGrone and Malawi health workers measuring the length of a child at a rural health center.
Photo credit: Indi Trehan
Child Stunting is Associated with Low Circulating Essential Amino Acids (2016). EBioMedicine 6, 246–252. http://www.ebiomedicine.com/article/S2352-3964%2816%2930069-X/fulltext