JMIR Publications

ABSTRACT

Background:

Protein is an essential macronutrient playing an important role during complementary feeding (CF). Low protein intake contributes to undernutrition while high intake especially from animal sources may increase obesity risk. However, the effects of different protein sources (dairy, meat and plants) on growth, and underlying mechanisms for these effects, are poorly understood. Animal source foods (ASFs) provide both high quality protein and iron and are recommended to improve iron status. However, it is unclear whether current dietary recommendations are adequate to support healthy growth and optimise iron status. These issues are of particular concern in countries facing double burden of malnutrition (DBM), the coexistence of all forms of malnutrition. More evidence is needed to develop appropriate recommendations for these countries.

Objective:

This study will investigate associations between protein intake during CF and growth, body composition, and iron status of infants in Thailand, a country facing the DBM. In addition, the study will explore how different protein sources influence growth via growth hormone (GH)-insulin like-growth factor I (IGF-1) axis and plasma amino acids.

Methods:

A multicentre cohort study will be conducted in Chiang Mai, Thailand in150 healthy term infants aged 4-6 months with birth weight ≥ 2,500 g. Demographic data, dietary intakes and anthropometry will be collected at 6, 9 and 12 months. Dietary intakes will be assessed using 24-hour food recalls, 3-day food records and food frequency questionnaires. Blood samples for iron status, GH, IGF-1, Insulin like-growth factor binding protein III (IGFBP-3) and plasma amino acids and urine samples for body composition analysis using stable isotope dilution will be obtained at 12 months old.

Results:

The recruitment of study participants and data collection was undertaken from June 2018 to May 2019. Data and laboratory analyses are ongoing and are expected to be completed by December 2020. A total of 150 participants enrolled, and 146 continued participating until the end of the study. We hypothesised that protein intake from ASFs in recommended quantities can support normal weight and length gain as well as lower risk of undernutrition than similar amounts of plant-based protein however, higher protein intake especially from milk protein may link to increase percentage of body fat mass via plasma amino acids and GH-IGF axis.

Conclusions:

The results from this study will provide data on current CF practices of Thai infants focusing on protein and iron intake. This information, combined with data on associations with infant growth and iron status, will help inform CF recommendations for this population and may also be relevant to other settings experiencing the DBM.