Key Take outs from the Review
Children experiencing growth faltering have inadequate intakes of 9 essential amino acids which has a negative impact on linear growth via the mTORC1 pathway. The inclusion of protein-rich animal food sources, including dairy, should be encouraged to improve the intake of EAAs and the overall diet quality of children in Low-Middle Income Countries.
In this review, Parikh et al (2021) considered the evidence for the role of protein and more specifically essential amino acids (EAAs) for linear growth and neurocognitive development in children below 5 years in LMICs. Physical growth of infants and young children is internationally recognised as the best indicator for their well-being and development of full physical and mental potentials, the authors stated. However, recent estimates suggest that many infants and young children suffer from stunting or linear growth faltering. In 2018, ±149 million children, aged under 5 years in Low-Middle Income Countries (LMICs) around the world, experienced poor growth and stunting as reported by UNICEF.
Key points from the review
- Protein and essential amino acids (EAAs) support linear growth and potentially neurocognitive development in infants and young children.
- Many children in LMICs with diets based on starchy staple foods such as rice, wheat, maize (corn) millet, sorghum, roots and tubers have inadequate intakes of EAAs.
- Protein cannot be regarded as a single, homogeneous nutrient,
- A growing body of evidence suggesting that children experiencing growth faltering have inadequate intakes of these EAAs.
- Inadequate intake of the EAAs most likely has a negative impact on linear growth via the mTORC1 pathway (Figure 1)
- Inclusion of protein-rich animal food sources should be encouraged to improve intake of EAAs and overall diet quality of children in LMICs.
- Further in-depth research into AA intakes and concentrations in infants and young children presenting with varying physiological states across a wide range of geographical regions should be carried out so that appropriate nutritional strategies can be developed in the future.
Role of the mammalian target of rapamycin complex 1 (mTORC1) pathway
The authors discussed that the mTORC1 pathway shown in Figure 1 is one of the main amino acid (AA)-sensing hubs and a master regulator of growth and development. It has been shown that amino acids are key drivers for mTORC1 and its activity is regulated via the availability of amino acids, energy and growth factors.
The authors concluded that animal source foods, rich in EAAs, are important for supporting linear growth and development of young children in LMICs.
Figure 1 Obtained from the review by Parikh et al 2021. Amino acid sensing by mammalian target of rapamycin complex 1 (mTORC1)
Conclusion from the review
Many children in LMICs, who experience growth faltering, have inadequate intakes of EAAs, partly attributable to the poor protein quality of their diets. It has been shown that the amino acid sensing mTORC1 pathway is an important regulator of overall growth and development and can be activated by AAs and a number of other signals, including cytokines (e.g., tumour necrosis factor α), growth factors (e.g., insulin-like growth factor 1 [IGF1]) and cellular energy status. The authors conclude that EAAs can influence linear growth via the mTORC1 pathway and that animal source foods, rich in EAAs and sources of high-quality protein and fatty acids should be included in complementary feeding to reduce the risk of linear growth faltering.
The authors also highlight the need for further investigation of amino acid intakes and requirements in infants and young children in developing countries in order to better design future nutritional interventions and strategies.
Parikh, P., Semba, R., Manary, M., Swaminathan, S., Udomkesmalee, E., Bos, R., Poh, B. K., Rojroongwasinkul, N., Geurts, J., Sekartini, R., & Nga, T. T. (2021). Animal source foods, rich in essential amino acids, are important for linear growth and development of young children in low- and middle-income countries. Maternal & Child Nutrition, e13264. https://doi.org/10.1111/mcn.13264